In order to allow kprobes to skip the ENDBR instructions at sym+0 for
X86_KERNEL_IBT builds, change _kprobe_addr() to take an architecture
callback to inspect the function at hand and modify the offset if
needed.
This streamlines the existing interface to cover more cases and
require less hooks. Once PowerPC gets fully converted there will only
be the one arch hook.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154318.405947704@infradead.org
Return trampoline must not use indirect branch to return; while this
preserves the RSB, it is fundamentally incompatible with IBT. Instead
use a retpoline like ROP gadget that defeats IBT while not unbalancing
the RSB.
And since ftrace_stub is no longer a plain RET, don't use it to copy
from. Since RET is a trivial instruction, poke it directly.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154318.347296408@infradead.org
Currently a lot of ftrace code assumes __fentry__ is at sym+0. However
with Intel IBT enabled the first instruction of a function will most
likely be ENDBR.
Change ftrace_location() to not only return the __fentry__ location
when called for the __fentry__ location, but also when called for the
sym+0 location.
Then audit/update all callsites of this function to consistently use
these new semantics.
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154318.227581603@infradead.org
The code does:
## branch into array
mov jump_table(,%rax,8), %bufp
JMP_NOSPEC bufp
resulting in needing to mark the jump-table entries with ENDBR.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154318.110500806@infradead.org
Ensure the ASM functions have ENDBR on for IBT builds, this follows
the ARM64 example. Unlike ARM64, we'll likely end up overwriting them
with poison.
Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154317.992708941@infradead.org
Kernel entry points should be having ENDBR on for IBT configs.
The SYSCALL entry points are found through taking their respective
address in order to program them in the MSRs, while the exception
entry points are found through UNWIND_HINT_IRET_REGS.
The rule is that any UNWIND_HINT_IRET_REGS at sym+0 should have an
ENDBR, see the later objtool ibt validation patch.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154317.933157479@infradead.org
Even though Xen currently doesn't advertise IBT, prepare for when it
will eventually do so and sprinkle the ENDBR dust accordingly.
Even though most of the entry points are IRET like, the CPL0
Hypervisor can set WAIT-FOR-ENDBR and demand ENDBR at these sites.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154317.873919996@infradead.org
By doing an early rewrite of 'jmp native_iret` in
restore_regs_and_return_to_kernel() we can get rid of the last
INTERRUPT_RETURN user and paravirt_iret.
Suggested-by: Andrew Cooper <Andrew.Cooper3@citrix.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154317.815039833@infradead.org
Since commit 5c8f6a2e31 ("x86/xen: Add
xenpv_restore_regs_and_return_to_usermode()") Xen will no longer reach
this code and we can do away with the paravirt
SWAPGS/INTERRUPT_RETURN.
Suggested-by: Andrew Cooper <Andrew.Cooper3@citrix.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154317.756014488@infradead.org
Add Kconfig, Makefile and basic instruction support for x86 IBT.
(Ab)use __DISABLE_EXPORTS to disable IBT since it's already employed
to mark compressed and purgatory. Additionally mark realmode with it
as well to avoid inserting ENDBR instructions there. While ENDBR is
technically a NOP, inserting them was causing some grief due to code
growth. There's also a problem with using __noendbr in code compiled
without -fcf-protection=branch.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154317.519875203@infradead.org
The current annotation relies on not running objtool on the file; this
won't work when running objtool on vmlinux.o. Instead explicitly mark
__efi64_thunk() to be ignored.
This preserves the status quo, which is somewhat unfortunate. Luckily
this code is hardly ever used.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154317.402118218@infradead.org
* for-next/linkage:
arm64: module: remove (NOLOAD) from linker script
linkage: remove SYM_FUNC_{START,END}_ALIAS()
x86: clean up symbol aliasing
arm64: clean up symbol aliasing
linkage: add SYM_FUNC_ALIAS{,_LOCAL,_WEAK}()
swapped back into EPC memory
- Prevent do_int3() from being kprobed, to avoid recursion
- Remap setup_data and setup_indirect structures properly when accessing
their members
- Correct the alternatives patching order for modules too
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Merge tag 'x86_urgent_for_v5.17_rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Borislav Petkov:
- Free shmem backing storage for SGX enclave pages when those are
swapped back into EPC memory
- Prevent do_int3() from being kprobed, to avoid recursion
- Remap setup_data and setup_indirect structures properly when
accessing their members
- Correct the alternatives patching order for modules too
* tag 'x86_urgent_for_v5.17_rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/sgx: Free backing memory after faulting the enclave page
x86/traps: Mark do_int3() NOKPROBE_SYMBOL
x86/boot: Add setup_indirect support in early_memremap_is_setup_data()
x86/boot: Fix memremap of setup_indirect structures
x86/module: Fix the paravirt vs alternative order
There is a limited amount of SGX memory (EPC) on each system. When that
memory is used up, SGX has its own swapping mechanism which is similar
in concept but totally separate from the core mm/* code. Instead of
swapping to disk, SGX swaps from EPC to normal RAM. That normal RAM
comes from a shared memory pseudo-file and can itself be swapped by the
core mm code. There is a hierarchy like this:
EPC <-> shmem <-> disk
After data is swapped back in from shmem to EPC, the shmem backing
storage needs to be freed. Currently, the backing shmem is not freed.
This effectively wastes the shmem while the enclave is running. The
memory is recovered when the enclave is destroyed and the backing
storage freed.
Sort this out by freeing memory with shmem_truncate_range(), as soon as
a page is faulted back to the EPC. In addition, free the memory for
PCMD pages as soon as all PCMD's in a page have been marked as unused
by zeroing its contents.
Cc: stable@vger.kernel.org
Fixes: 1728ab54b4 ("x86/sgx: Add a page reclaimer")
Reported-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/20220303223859.273187-1-jarkko@kernel.org
Since kprobe_int3_handler() is called in do_int3(), probing do_int3()
can cause a breakpoint recursion and crash the kernel. Therefore,
do_int3() should be marked as NOKPROBE_SYMBOL.
Fixes: 21e28290b3 ("x86/traps: Split int3 handler up")
Signed-off-by: Li Huafei <lihuafei1@huawei.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220310120915.63349-1-lihuafei1@huawei.com
The syscall_handler_t type for x86_64 was defined as 'long (*)(void)',
but always cast to 'long (*)(long, long, long, long, long, long)' before
use. This now triggers a warning (see below).
Define syscall_handler_t as the latter instead, and remove the cast.
This simplifies the code, and fixes the warning.
Warning:
In file included from ../arch/um/include/asm/processor-generic.h:13
from ../arch/x86/um/asm/processor.h:41
from ../include/linux/rcupdate.h:30
from ../include/linux/rculist.h:11
from ../include/linux/pid.h:5
from ../include/linux/sched.h:14
from ../include/linux/ptrace.h:6
from ../arch/um/kernel/skas/syscall.c:7:
../arch/um/kernel/skas/syscall.c: In function ‘handle_syscall’:
../arch/x86/um/shared/sysdep/syscalls_64.h:18:11: warning: cast between incompatible function types from ‘long int (*)(void)’ to ‘long int (*)(long int, long int, long int, long int, long int, long int)’ [
-Wcast-function-type]
18 | (((long (*)(long, long, long, long, long, long)) \
| ^
../arch/x86/um/asm/ptrace.h:36:62: note: in definition of macro ‘PT_REGS_SET_SYSCALL_RETURN’
36 | #define PT_REGS_SET_SYSCALL_RETURN(r, res) (PT_REGS_AX(r) = (res))
| ^~~
../arch/um/kernel/skas/syscall.c:46:33: note: in expansion of macro ‘EXECUTE_SYSCALL’
46 | EXECUTE_SYSCALL(syscall, regs));
| ^~~~~~~~~~~~~~~
Signed-off-by: David Gow <davidgow@google.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Fix following includecheck warning:
./arch/x86/um/syscalls_64.c: registers.h is included more than once.
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Fixes: dbba7f704a ("um: stop polluting the namespace with registers.h contents")
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Now that all of the definitions have moved out of tracehook.h into
ptrace.h, sched/signal.h, resume_user_mode.h there is nothing left in
tracehook.h so remove it.
Update the few files that were depending upon tracehook.h to bring in
definitions to use the headers they need directly.
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20220309162454.123006-13-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Always handle TIF_NOTIFY_SIGNAL in get_signal. With commit 35d0b389f3
("task_work: unconditionally run task_work from get_signal()") always
calling task_work_run all of the work of tracehook_notify_signal is
already happening except clearing TIF_NOTIFY_SIGNAL.
Factor clear_notify_signal out of tracehook_notify_signal and use it in
get_signal so that get_signal only needs one call of task_work_run.
To keep the semantics in sync update xfer_to_guest_mode_work (which
does not call get_signal) to call tracehook_notify_signal if either
_TIF_SIGPENDING or _TIF_NOTIFY_SIGNAL.
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20220309162454.123006-8-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Break a header file circular dependency by removing the unnecessary
include of task_work.h from posix_timers.h.
sched.h -> posix-timers.h
posix-timers.h -> task_work.h
task_work.h -> sched.h
Add missing includes of task_work.h to:
arch/x86/mm/tlb.c
kernel/time/posix-cpu-timers.c
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20220309162454.123006-6-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
init_freq_invariance_cppc() was called in acpi_cppc_processor_probe(),
after CPU performance information and controls were populated from the
per-cpu _CPC objects.
But these _CPC objects provide information that helps with both CPU
(u-arch) and frequency invariance. Therefore, change the function name
to a more generic one, while adding the arch_ prefix, as this function
is expected to be defined differently by different architectures.
Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Fix the following W=1 kernel warnings:
arch/x86/xen/setup.c:725: warning: expecting prototype for
machine_specific_memory_setup(). Prototype was for xen_memory_setup()
instead.
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/20220307062554.8334-1-jiapeng.chong@linux.alibaba.com
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
The sched_clock() can be used very early since commit 857baa87b6
("sched/clock: Enable sched clock early"). In addition, with commit
38669ba205 ("x86/xen/time: Output xen sched_clock time from 0"), kdump
kernel in Xen HVM guest may panic at very early stage when accessing
&__this_cpu_read(xen_vcpu)->time as in below:
setup_arch()
-> init_hypervisor_platform()
-> x86_init.hyper.init_platform = xen_hvm_guest_init()
-> xen_hvm_init_time_ops()
-> xen_clocksource_read()
-> src = &__this_cpu_read(xen_vcpu)->time;
This is because Xen HVM supports at most MAX_VIRT_CPUS=32 'vcpu_info'
embedded inside 'shared_info' during early stage until xen_vcpu_setup() is
used to allocate/relocate 'vcpu_info' for boot cpu at arbitrary address.
However, when Xen HVM guest panic on vcpu >= 32, since
xen_vcpu_info_reset(0) would set per_cpu(xen_vcpu, cpu) = NULL when
vcpu >= 32, xen_clocksource_read() on vcpu >= 32 would panic.
This patch calls xen_hvm_init_time_ops() again later in
xen_hvm_smp_prepare_boot_cpu() after the 'vcpu_info' for boot vcpu is
registered when the boot vcpu is >= 32.
This issue can be reproduced on purpose via below command at the guest
side when kdump/kexec is enabled:
"taskset -c 33 echo c > /proc/sysrq-trigger"
The bugfix for PVM is not implemented due to the lack of testing
environment.
[boris: xen_hvm_init_time_ops() returns on errors instead of jumping to end]
Cc: Joe Jin <joe.jin@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/20220302164032.14569-3-dongli.zhang@oracle.com
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
The x86 boot documentation describes the setup_indirect structures and
how they are used. Only one of the two functions in ioremap.c that needed
to be modified to be aware of the introduction of setup_indirect
functionality was updated. Adds comparable support to the other function
where it was missing.
Fixes: b3c72fc9a7 ("x86/boot: Introduce setup_indirect")
Signed-off-by: Ross Philipson <ross.philipson@oracle.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/1645668456-22036-3-git-send-email-ross.philipson@oracle.com
As documented, the setup_indirect structure is nested inside
the setup_data structures in the setup_data list. The code currently
accesses the fields inside the setup_indirect structure but only
the sizeof(struct setup_data) is being memremapped. No crash
occurred but this is just due to how the area is remapped under the
covers.
Properly memremap both the setup_data and setup_indirect structures
in these cases before accessing them.
Fixes: b3c72fc9a7 ("x86/boot: Introduce setup_indirect")
Signed-off-by: Ross Philipson <ross.philipson@oracle.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/1645668456-22036-2-git-send-email-ross.philipson@oracle.com
Hyper-V provides host version number information that is output in
text form by a Linux guest when it boots. For whatever reason, the
formatting has historically been non-standard. Change it to output
in normal Windows version format for better readability.
Similar code for ARM64 guests already outputs in normal Windows
version format.
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1646767364-2234-1-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
On this board the ACPI RSDP structure points to both a RSDT and an XSDT,
but the XSDT points to a truncated FADT. This causes all sorts of trouble
and usually a complete failure to boot after the following error occurs:
ACPI Error: Unsupported address space: 0x20 (*/hwregs-*)
ACPI Error: AE_SUPPORT, Unable to initialize fixed events (*/evevent-*)
ACPI: Unable to start ACPI Interpreter
This leaves the ACPI implementation in such a broken state that subsequent
kernel subsystem initialisations go wrong, resulting in among others
mismapped PCI memory, SATA and USB enumeration failures, and freezes.
As this is an older embedded platform that will likely never see any BIOS
updates to address this issue and its default shipping OS only complies to
ACPI 1.0, work around this by forcing `acpi=rsdt`. This patch, applied on
top of Linux 5.10.102, was confirmed on real hardware to fix the issue.
Signed-off-by: Mark Cilissen <mark@yotsuba.nl>
Cc: All applicable <stable@vger.kernel.org>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The init_freq_invariance_cppc code actually doesn't need the SMP
functionality. So setting the CONFIG_SMP as the check condition for
init_freq_invariance_cppc may cause the confusion to misunderstand the
CPPC. And the x86 CPPC file is better space to store the CPPC related
functions, while the init_freq_invariance_cppc is out of smpboot, that
means, the CONFIG_SMP won't be mandatory condition any more. And It's more
clear than before.
Signed-off-by: Huang Rui <ray.huang@amd.com>
[ rjw: Subject adjustment ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The function init_freq_invariance will be used on x86 CPPC, so expose it in
the topology header.
Signed-off-by: Huang Rui <ray.huang@amd.com>
[ rjw: Subject adjustment ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The AMD maximum frequency ratio setting function depends on CPPC, so the
x86 CPPC implementation file is better space for this function.
Signed-off-by: Huang Rui <ray.huang@amd.com>
[ rjw: Subject adjustment ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Rename the cppc_msr.c to cppc.c in x86 ACPI, that expects to use this file
to cover more function implementation for ACPI CPPC beside MSR helpers.
Naming as "cppc" is more straightforward as one of the functionalities
under ACPI subsystem.
Signed-off-by: Huang Rui <ray.huang@amd.com>
[ rjw: Subject ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Expand KVM's mask for the AVIC host physical ID to the full 12 bits defined
by the architecture. The number of bits consumed by hardware is model
specific, e.g. early CPUs ignored bits 11:8, but there is no way for KVM
to enumerate the "true" size. So, KVM must allow using all bits, else it
risks rejecting completely legal x2APIC IDs on newer CPUs.
This means KVM relies on hardware to not assign x2APIC IDs that exceed the
"true" width of the field, but presumably hardware is smart enough to tie
the width to the max x2APIC ID. KVM also relies on hardware to support at
least 8 bits, as the legacy xAPIC ID is writable by software. But, those
assumptions are unavoidable due to the lack of any way to enumerate the
"true" width.
Cc: stable@vger.kernel.org
Cc: Maxim Levitsky <mlevitsk@redhat.com>
Suggested-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Fixes: 44a95dae1d ("KVM: x86: Detect and Initialize AVIC support")
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Message-Id: <20220211000851.185799-1-suravee.suthikulpanit@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Disallow calling tdp_mmu_set_spte_atomic() with a REMOVED "old" SPTE.
This solves a conundrum introduced by commit 3255530ab1 ("KVM: x86/mmu:
Automatically update iter->old_spte if cmpxchg fails"); if the helper
doesn't update old_spte in the REMOVED case, then theoretically the
caller could get stuck in an infinite loop as it will fail indefinitely
on the REMOVED SPTE. E.g. until recently, clear_dirty_gfn_range() didn't
check for a present SPTE and would have spun until getting rescheduled.
In practice, only the page fault path should "create" a new SPTE, all
other paths should only operate on existing, a.k.a. shadow present,
SPTEs. Now that the page fault path pre-checks for a REMOVED SPTE in all
cases, require all other paths to indirectly pre-check by verifying the
target SPTE is a shadow-present SPTE.
Note, this does not guarantee the actual SPTE isn't REMOVED, nor is that
scenario disallowed. The invariant is only that the caller mustn't
invoke tdp_mmu_set_spte_atomic() if the SPTE was REMOVED when last
observed by the caller.
Cc: David Matlack <dmatlack@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220226001546.360188-25-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Explicitly check for a REMOVED leaf SPTE prior to attempting to map
the final SPTE when handling a TDP MMU fault. Functionally, this is a
nop as tdp_mmu_set_spte_atomic() will eventually detect the frozen SPTE.
Pre-checking for a REMOVED SPTE is a minor optmization, but the real goal
is to allow tdp_mmu_set_spte_atomic() to have an invariant that the "old"
SPTE is never a REMOVED SPTE.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-24-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Zap defunct roots, a.k.a. roots that have been invalidated after their
last reference was initially dropped, asynchronously via the existing work
queue instead of forcing the work upon the unfortunate task that happened
to drop the last reference.
If a vCPU task drops the last reference, the vCPU is effectively blocked
by the host for the entire duration of the zap. If the root being zapped
happens be fully populated with 4kb leaf SPTEs, e.g. due to dirty logging
being active, the zap can take several hundred seconds. Unsurprisingly,
most guests are unhappy if a vCPU disappears for hundreds of seconds.
E.g. running a synthetic selftest that triggers a vCPU root zap with
~64tb of guest memory and 4kb SPTEs blocks the vCPU for 900+ seconds.
Offloading the zap to a worker drops the block time to <100ms.
There is an important nuance to this change. If the same work item
was queued twice before the work function has run, it would only
execute once and one reference would be leaked. Therefore, now that
queueing and flushing items is not anymore protected by kvm->slots_lock,
kvm_tdp_mmu_invalidate_all_roots() has to check root->role.invalid and
skip already invalid roots. On the other hand, kvm_mmu_zap_all_fast()
must return only after those skipped roots have been zapped as well.
These two requirements can be satisfied only if _all_ places that
change invalid to true now schedule the worker before releasing the
mmu_lock. There are just two, kvm_tdp_mmu_put_root() and
kvm_tdp_mmu_invalidate_all_roots().
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-23-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When zapping a TDP MMU root, perform the zap in two passes to avoid
zapping an entire top-level SPTE while holding RCU, which can induce RCU
stalls. In the first pass, zap SPTEs at PG_LEVEL_1G, and then
zap top-level entries in the second pass.
With 4-level paging, zapping a PGD that is fully populated with 4kb leaf
SPTEs take up to ~7 or so seconds (time varies based on kernel config,
number of (v)CPUs, etc...). With 5-level paging, that time can balloon
well into hundreds of seconds.
Before remote TLB flushes were omitted, the problem was even worse as
waiting for all active vCPUs to respond to the IPI introduced significant
overhead for VMs with large numbers of vCPUs.
By zapping 1gb SPTEs (both shadow pages and hugepages) in the first pass,
the amount of work that is done without dropping RCU protection is
strictly bounded, with the worst case latency for a single operation
being less than 100ms.
Zapping at 1gb in the first pass is not arbitrary. First and foremost,
KVM relies on being able to zap 1gb shadow pages in a single shot when
when repacing a shadow page with a hugepage. Zapping a 1gb shadow page
that is fully populated with 4kb dirty SPTEs also triggers the worst case
latency due writing back the struct page accessed/dirty bits for each 4kb
page, i.e. the two-pass approach is guaranteed to work so long as KVM can
cleany zap a 1gb shadow page.
rcu: INFO: rcu_sched self-detected stall on CPU
rcu: 52-....: (20999 ticks this GP) idle=7be/1/0x4000000000000000
softirq=15759/15759 fqs=5058
(t=21016 jiffies g=66453 q=238577)
NMI backtrace for cpu 52
Call Trace:
...
mark_page_accessed+0x266/0x2f0
kvm_set_pfn_accessed+0x31/0x40
handle_removed_tdp_mmu_page+0x259/0x2e0
__handle_changed_spte+0x223/0x2c0
handle_removed_tdp_mmu_page+0x1c1/0x2e0
__handle_changed_spte+0x223/0x2c0
handle_removed_tdp_mmu_page+0x1c1/0x2e0
__handle_changed_spte+0x223/0x2c0
zap_gfn_range+0x141/0x3b0
kvm_tdp_mmu_zap_invalidated_roots+0xc8/0x130
kvm_mmu_zap_all_fast+0x121/0x190
kvm_mmu_invalidate_zap_pages_in_memslot+0xe/0x10
kvm_page_track_flush_slot+0x5c/0x80
kvm_arch_flush_shadow_memslot+0xe/0x10
kvm_set_memslot+0x172/0x4e0
__kvm_set_memory_region+0x337/0x590
kvm_vm_ioctl+0x49c/0xf80
Reported-by: David Matlack <dmatlack@google.com>
Cc: Ben Gardon <bgardon@google.com>
Cc: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-22-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Allow yielding when zapping SPTEs after the last reference to a valid
root is put. Because KVM must drop all SPTEs in response to relevant
mmu_notifier events, mark defunct roots invalid and reset their refcount
prior to zapping the root. Keeping the refcount elevated while the zap
is in-progress ensures the root is reachable via mmu_notifier until the
zap completes and the last reference to the invalid, defunct root is put.
Allowing kvm_tdp_mmu_put_root() to yield fixes soft lockup issues if the
root in being put has a massive paging structure, e.g. zapping a root
that is backed entirely by 4kb pages for a guest with 32tb of memory can
take hundreds of seconds to complete.
watchdog: BUG: soft lockup - CPU#49 stuck for 485s! [max_guest_memor:52368]
RIP: 0010:kvm_set_pfn_dirty+0x30/0x50 [kvm]
__handle_changed_spte+0x1b2/0x2f0 [kvm]
handle_removed_tdp_mmu_page+0x1a7/0x2b8 [kvm]
__handle_changed_spte+0x1f4/0x2f0 [kvm]
handle_removed_tdp_mmu_page+0x1a7/0x2b8 [kvm]
__handle_changed_spte+0x1f4/0x2f0 [kvm]
tdp_mmu_zap_root+0x307/0x4d0 [kvm]
kvm_tdp_mmu_put_root+0x7c/0xc0 [kvm]
kvm_mmu_free_roots+0x22d/0x350 [kvm]
kvm_mmu_reset_context+0x20/0x60 [kvm]
kvm_arch_vcpu_ioctl_set_sregs+0x5a/0xc0 [kvm]
kvm_vcpu_ioctl+0x5bd/0x710 [kvm]
__se_sys_ioctl+0x77/0xc0
__x64_sys_ioctl+0x1d/0x20
do_syscall_64+0x44/0xa0
entry_SYSCALL_64_after_hwframe+0x44/0xae
KVM currently doesn't put a root from a non-preemptible context, so other
than the mmu_notifier wrinkle, yielding when putting a root is safe.
Yield-unfriendly iteration uses for_each_tdp_mmu_root(), which doesn't
take a reference to each root (it requires mmu_lock be held for the
entire duration of the walk).
tdp_mmu_next_root() is used only by the yield-friendly iterator.
tdp_mmu_zap_root_work() is explicitly yield friendly.
kvm_mmu_free_roots() => mmu_free_root_page() is a much bigger fan-out,
but is still yield-friendly in all call sites, as all callers can be
traced back to some combination of vcpu_run(), kvm_destroy_vm(), and/or
kvm_create_vm().
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220226001546.360188-21-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Use the system worker threads to zap the roots invalidated
by the TDP MMU's "fast zap" mechanism, implemented by
kvm_tdp_mmu_invalidate_all_roots().
At this point, apart from allowing some parallelism in the zapping of
roots, the workqueue is a glorified linked list: work items are added and
flushed entirely within a single kvm->slots_lock critical section. However,
the workqueue fixes a latent issue where kvm_mmu_zap_all_invalidated_roots()
assumes that it owns a reference to all invalid roots; therefore, no
one can set the invalid bit outside kvm_mmu_zap_all_fast(). Putting the
invalidated roots on a linked list... erm, on a workqueue ensures that
tdp_mmu_zap_root_work() only puts back those extra references that
kvm_mmu_zap_all_invalidated_roots() had gifted to it.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Defer TLB flushes to the caller when freeing TDP MMU shadow pages instead
of immediately flushing. Because the shadow pages are freed in an RCU
callback, so long as at least one CPU holds RCU, all CPUs are protected.
For vCPUs running in the guest, i.e. consuming TLB entries, KVM only
needs to ensure the caller services the pending TLB flush before dropping
its RCU protections. I.e. use the caller's RCU as a proxy for all vCPUs
running in the guest.
Deferring the flushes allows batching flushes, e.g. when installing a
1gb hugepage and zapping a pile of SPs. And when zapping an entire root,
deferring flushes allows skipping the flush entirely (because flushes are
not needed in that case).
Avoiding flushes when zapping an entire root is especially important as
synchronizing with other CPUs via IPI after zapping every shadow page can
cause significant performance issues for large VMs. The issue is
exacerbated by KVM zapping entire top-level entries without dropping
RCU protection, which can lead to RCU stalls even when zapping roots
backing relatively "small" amounts of guest memory, e.g. 2tb. Removing
the IPI bottleneck largely mitigates the RCU issues, though it's likely
still a problem for 5-level paging. A future patch will further address
the problem by zapping roots in multiple passes to avoid holding RCU for
an extended duration.
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220226001546.360188-20-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When yielding in the TDP MMU iterator, service any pending TLB flush
before dropping RCU protections in anticipation of using the caller's RCU
"lock" as a proxy for vCPUs in the guest.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-19-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Zap only leaf SPTEs in the TDP MMU's zap_gfn_range(), and rename various
functions accordingly. When removing mappings for functional correctness
(except for the stupid VFIO GPU passthrough memslots bug), zapping the
leaf SPTEs is sufficient as the paging structures themselves do not point
at guest memory and do not directly impact the final translation (in the
TDP MMU).
Note, this aligns the TDP MMU with the legacy/full MMU, which zaps only
the rmaps, a.k.a. leaf SPTEs, in kvm_zap_gfn_range() and
kvm_unmap_gfn_range().
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-18-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Now that all callers of zap_gfn_range() hold mmu_lock for write, drop
support for zapping with mmu_lock held for read. That all callers hold
mmu_lock for write isn't a random coincidence; now that the paths that
need to zap _everything_ have their own path, the only callers left are
those that need to zap for functional correctness. And when zapping is
required for functional correctness, mmu_lock must be held for write,
otherwise the caller has no guarantees about the state of the TDP MMU
page tables after it has run, e.g. the SPTE(s) it zapped can be
immediately replaced by a vCPU faulting in a page.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-17-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add a dedicated helper for zapping a TDP MMU root, and use it in the three
flows that do "zap_all" and intentionally do not do a TLB flush if SPTEs
are zapped (zapping an entire root is safe if and only if it cannot be in
use by any vCPU). Because a TLB flush is never required, unconditionally
pass "false" to tdp_mmu_iter_cond_resched() when potentially yielding.
Opportunistically document why KVM must not yield when zapping roots that
are being zapped by kvm_tdp_mmu_put_root(), i.e. roots whose refcount has
reached zero, and further harden the flow to detect improper KVM behavior
with respect to roots that are supposed to be unreachable.
In addition to hardening zapping of roots, isolating zapping of roots
will allow future simplification of zap_gfn_range() by having it zap only
leaf SPTEs, and by removing its tricky "zap all" heuristic. By having
all paths that truly need to free _all_ SPs flow through the dedicated
root zapper, the generic zapper can be freed of those concerns.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-16-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Don't flush the TLBs when zapping all TDP MMU pages, as the only time KVM
uses the slow version of "zap everything" is when the VM is being
destroyed or the owning mm has exited. In either case, KVM_RUN is
unreachable for the VM, i.e. the guest TLB entries cannot be consumed.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-15-seanjc@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When recovering a potential hugepage that was shattered for the iTLB
multihit workaround, precisely zap only the target page instead of
iterating over the TDP MMU to find the SP that was passed in. This will
allow future simplification of zap_gfn_range() by having it zap only
leaf SPTEs.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220226001546.360188-14-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Refactor __tdp_mmu_set_spte() to work with raw values instead of a
tdp_iter objects so that a future patch can modify SPTEs without doing a
walk, and without having to synthesize a tdp_iter.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-13-seanjc@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
WARN if the new_spte being set by __tdp_mmu_set_spte() is a REMOVED_SPTE,
which is called out by the comment as being disallowed but not actually
checked. Keep the WARN on the old_spte as well, because overwriting a
REMOVED_SPTE in the non-atomic path is also disallowed (as evidence by
lack of splats with the existing WARN).
Fixes: 08f07c800e ("KVM: x86/mmu: Flush TLBs after zap in TDP MMU PF handler")
Cc: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-12-seanjc@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add helpers to read and write TDP MMU SPTEs instead of open coding
rcu_dereference() all over the place, and to provide a convenient
location to document why KVM doesn't exempt holding mmu_lock for write
from having to hold RCU (and any future changes to the rules).
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-11-seanjc@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Drop RCU protection after processing each root when handling MMU notifier
hooks that aren't the "unmap" path, i.e. aren't zapping. Temporarily
drop RCU to let RCU do its thing between roots, and to make it clear that
there's no special behavior that relies on holding RCU across all roots.
Currently, the RCU protection is completely superficial, it's necessary
only to make rcu_dereference() of SPTE pointers happy. A future patch
will rely on holding RCU as a proxy for vCPUs in the guest, e.g. to
ensure shadow pages aren't freed before all vCPUs do a TLB flush (or
rather, acknowledge the need for a flush), but in that case RCU needs to
be held until the flush is complete if and only if the flush is needed
because a shadow page may have been removed. And except for the "unmap"
path, MMU notifier events cannot remove SPs (don't toggle PRESENT bit,
and can't change the PFN for a SP).
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-10-seanjc@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Batch TLB flushes (with other MMUs) when handling ->change_spte()
notifications in the TDP MMU. The MMU notifier path in question doesn't
allow yielding and correcty flushes before dropping mmu_lock.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-9-seanjc@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Look for a !leaf=>leaf conversion instead of a PFN change when checking
if a SPTE change removed a TDP MMU shadow page. Convert the PFN check
into a WARN, as KVM should never change the PFN of a shadow page (except
when its being zapped or replaced).
From a purely theoretical perspective, it's not illegal to replace a SP
with a hugepage pointing at the same PFN. In practice, it's impossible
as that would require mapping guest memory overtop a kernel-allocated SP.
Either way, the check is odd.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-8-seanjc@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Remove the "shared" argument of for_each_tdp_mmu_root_yield_safe, thus ensuring
that readers do not ever acquire a reference to an invalid root. After this
patch, all readers except kvm_tdp_mmu_zap_invalidated_roots() treat
refcount=0/valid, refcount=0/invalid and refcount=1/invalid in exactly the
same way. kvm_tdp_mmu_zap_invalidated_roots() is different but it also
does not acquire a reference to the invalid root, and it cannot see
refcount=0/invalid because it is guaranteed to run after
kvm_tdp_mmu_invalidate_all_roots().
Opportunistically add a lockdep assertion to the yield-safe iterator.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Eager page splitting is an optimization; it does not have to be performed on
invalid roots. It is also the only case in which a reader might acquire
a reference to an invalid root, so after this change we know that readers
will skip both dying and invalid roots.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Assert that mmu_lock is held for write by users of the yield-unfriendly
TDP iterator. The nature of a shared walk means that the caller needs to
play nice with other tasks modifying the page tables, which is more or
less the same thing as playing nice with yielding. Theoretically, KVM
could gain a flow where it could legitimately take mmu_lock for read in
a non-preemptible context, but that's highly unlikely and any such case
should be viewed with a fair amount of scrutiny.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Remove the misleading flush "handling" when zapping invalidated TDP MMU
roots, and document that flushing is unnecessary for all flavors of MMUs
when zapping invalid/obsolete roots/pages. The "handling" in the TDP MMU
is dead code, as zap_gfn_range() is called with shared=true, in which
case it will never return true due to the flushing being handled by
tdp_mmu_zap_spte_atomic().
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Explicitly ignore the result of zap_gfn_range() when putting the last
reference to a TDP MMU root, and add a pile of comments to formalize the
TDP MMU's behavior of deferring TLB flushes to alloc/reuse. Note, this
only affects the !shared case, as zap_gfn_range() subtly never returns
true for "flush" as the flush is handled by tdp_mmu_zap_spte_atomic().
Putting the root without a flush is ok because even if there are stale
references to the root in the TLB, they are unreachable because KVM will
not run the guest with the same ASID without first flushing (where ASID
in this context refers to both SVM's explicit ASID and Intel's implicit
ASID that is constructed from VPID+PCID+EPT4A+etc...).
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220226001546.360188-5-seanjc@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Fix misleading and arguably wrong comments in the TDP MMU's fast zap
flow. The comments, and the fact that actually zapping invalid roots was
added separately, strongly suggests that zapping invalid roots is an
optimization and not required for correctness. That is a lie.
KVM _must_ zap invalid roots before returning from kvm_mmu_zap_all_fast(),
because when it's called from kvm_mmu_invalidate_zap_pages_in_memslot(),
KVM is relying on it to fully remove all references to the memslot. Once
the memslot is gone, KVM's mmu_notifier hooks will be unable to find the
stale references as the hva=>gfn translation is done via the memslots.
If KVM doesn't immediately zap SPTEs and userspace unmaps a range after
deleting a memslot, KVM will fail to zap in response to the mmu_notifier
due to not finding a memslot corresponding to the notifier's range, which
leads to a variation of use-after-free.
The other misleading comment (and code) explicitly states that roots
without a reference should be skipped. While that's technically true,
it's also extremely misleading as it should be impossible for KVM to
encounter a defunct root on the list while holding mmu_lock for write.
Opportunistically add a WARN to enforce that invariant.
Fixes: b7cccd397f ("KVM: x86/mmu: Fast invalidation for TDP MMU")
Fixes: 4c6654bd16 ("KVM: x86/mmu: Tear down roots before kvm_mmu_zap_all_fast returns")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Explicitly check for present SPTEs when clearing dirty bits in the TDP
MMU. This isn't strictly required for correctness, as setting the dirty
bit in a defunct SPTE will not change the SPTE from !PRESENT to PRESENT.
However, the guarded MMU_WARN_ON() in spte_ad_need_write_protect() would
complain if anyone actually turned on KVM's MMU debugging.
Fixes: a6a0b05da9 ("kvm: x86/mmu: Support dirty logging for the TDP MMU")
Cc: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-3-seanjc@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Allocations whose size is related to the memslot size can be arbitrarily
large. Do not use kvzalloc/kvcalloc, as those are limited to "not crazy"
sizes that fit in 32 bits.
Cc: stable@vger.kernel.org
Fixes: 7661809d49 ("mm: don't allow oversized kvmalloc() calls")
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Ever since commit
4e6292114c ("x86/paravirt: Add new features for paravirt patching")
there is an ordering dependency between patching paravirt ops and
patching alternatives, the module loader still violates this.
Fixes: 4e6292114c ("x86/paravirt: Add new features for paravirt patching")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220303112825.068773913@infradead.org
which support eIBRS, i.e., the hardware-assisted speculation restriction
after it has been shown that such machines are vulnerable even with the
hardware mitigation.
- Do not use the default LFENCE-based Spectre v2 mitigation on AMD as it
is insufficient to mitigate such attacks. Instead, switch to retpolines
on all AMD by default.
- Update the docs and add some warnings for the obviously vulnerable
cmdline configurations.
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Merge tag 'x86_bugs_for_v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 spectre fixes from Borislav Petkov:
- Mitigate Spectre v2-type Branch History Buffer attacks on machines
which support eIBRS, i.e., the hardware-assisted speculation
restriction after it has been shown that such machines are vulnerable
even with the hardware mitigation.
- Do not use the default LFENCE-based Spectre v2 mitigation on AMD as
it is insufficient to mitigate such attacks. Instead, switch to
retpolines on all AMD by default.
- Update the docs and add some warnings for the obviously vulnerable
cmdline configurations.
* tag 'x86_bugs_for_v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/speculation: Warn about eIBRS + LFENCE + Unprivileged eBPF + SMT
x86/speculation: Warn about Spectre v2 LFENCE mitigation
x86/speculation: Update link to AMD speculation whitepaper
x86/speculation: Use generic retpoline by default on AMD
x86/speculation: Include unprivileged eBPF status in Spectre v2 mitigation reporting
Documentation/hw-vuln: Update spectre doc
x86/speculation: Add eIBRS + Retpoline options
x86/speculation: Rename RETPOLINE_AMD to RETPOLINE_LFENCE
* Tweaks to the paravirtualization code, to avoid using them
when they're pointless or harmful
x86 host:
* Fix for SRCU lockdep splat
* Brown paper bag fix for the propagation of errno
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull kvm fixes from Paolo Bonzini:
"x86 guest:
- Tweaks to the paravirtualization code, to avoid using them when
they're pointless or harmful
x86 host:
- Fix for SRCU lockdep splat
- Brown paper bag fix for the propagation of errno"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: x86: pull kvm->srcu read-side to kvm_arch_vcpu_ioctl_run
KVM: x86/mmu: Passing up the error state of mmu_alloc_shadow_roots()
KVM: x86: Yield to IPI target vCPU only if it is busy
x86/kvmclock: Fix Hyper-V Isolated VM's boot issue when vCPUs > 64
x86/kvm: Don't waste memory if kvmclock is disabled
x86/kvm: Don't use PV TLB/yield when mwait is advertised
The commit
44a3918c82 ("x86/speculation: Include unprivileged eBPF status in Spectre v2 mitigation reporting")
added a warning for the "eIBRS + unprivileged eBPF" combination, which
has been shown to be vulnerable against Spectre v2 BHB-based attacks.
However, there's no warning about the "eIBRS + LFENCE retpoline +
unprivileged eBPF" combo. The LFENCE adds more protection by shortening
the speculation window after a mispredicted branch. That makes an attack
significantly more difficult, even with unprivileged eBPF. So at least
for now the logic doesn't warn about that combination.
But if you then add SMT into the mix, the SMT attack angle weakens the
effectiveness of the LFENCE considerably.
So extend the "eIBRS + unprivileged eBPF" warning to also include the
"eIBRS + LFENCE + unprivileged eBPF + SMT" case.
[ bp: Massage commit message. ]
Suggested-by: Alyssa Milburn <alyssa.milburn@linux.intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
With:
f8a66d608a ("x86,bugs: Unconditionally allow spectre_v2=retpoline,amd")
it became possible to enable the LFENCE "retpoline" on Intel. However,
Intel doesn't recommend it, as it has some weaknesses compared to
retpoline.
Now AMD doesn't recommend it either.
It can still be left available as a cmdline option. It's faster than
retpoline but is weaker in certain scenarios -- particularly SMT, but
even non-SMT may be vulnerable in some cases.
So just unconditionally warn if the user requests it on the cmdline.
[ bp: Massage commit message. ]
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Daniel Borkmann says:
====================
pull-request: bpf-next 2022-03-04
We've added 32 non-merge commits during the last 14 day(s) which contain
a total of 59 files changed, 1038 insertions(+), 473 deletions(-).
The main changes are:
1) Optimize BPF stackmap's build_id retrieval by caching last valid build_id,
as consecutive stack frames are likely to be in the same VMA and therefore
have the same build id, from Hao Luo.
2) Several improvements to arm64 BPF JIT, that is, support for JITing
the atomic[64]_fetch_add, atomic[64]_[fetch_]{and,or,xor} and lastly
atomic[64]_{xchg|cmpxchg}. Also fix the BTF line info dump for JITed
programs, from Hou Tao.
3) Optimize generic BPF map batch deletion by only enforcing synchronize_rcu()
barrier once upon return to user space, from Eric Dumazet.
4) For kernel build parse DWARF and generate BTF through pahole with enabled
multithreading, from Kui-Feng Lee.
5) BPF verifier usability improvements by making log info more concise and
replacing inv with scalar type name, from Mykola Lysenko.
6) Two follow-up fixes for BPF prog JIT pack allocator, from Song Liu.
7) Add a new Kconfig to allow for loading kernel modules with non-matching
BTF type info; their BTF info is then removed on load, from Connor O'Brien.
8) Remove reallocarray() usage from bpftool and switch to libbpf_reallocarray()
in order to fix compilation errors for older glibc, from Mauricio Vásquez.
9) Fix libbpf to error on conflicting name in BTF when type declaration
appears before the definition, from Xu Kuohai.
10) Fix issue in BPF preload for in-kernel light skeleton where loaded BPF
program fds prevent init process from setting up fd 0-2, from Yucong Sun.
11) Fix libbpf reuse of pinned perf RB map when max_entries is auto-determined
by libbpf, from Stijn Tintel.
12) Several cleanups for libbpf and a fix to enforce perf RB map #pages to be
non-zero, from Yuntao Wang.
* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (32 commits)
bpf: Small BPF verifier log improvements
libbpf: Add a check to ensure that page_cnt is non-zero
bpf, x86: Set header->size properly before freeing it
x86: Disable HAVE_ARCH_HUGE_VMALLOC on 32-bit x86
bpf, test_run: Fix overflow in XDP frags bpf_test_finish
selftests/bpf: Update btf_dump case for conflicting names
libbpf: Skip forward declaration when counting duplicated type names
bpf: Add some description about BPF_JIT_ALWAYS_ON in Kconfig
bpf, docs: Add a missing colon in verifier.rst
bpf: Cache the last valid build_id
libbpf: Fix BPF_MAP_TYPE_PERF_EVENT_ARRAY auto-pinning
bpf, selftests: Use raw_tp program for atomic test
bpf, arm64: Support more atomic operations
bpftool: Remove redundant slashes
bpf: Add config to allow loading modules with BTF mismatches
bpf, arm64: Feed byte-offset into bpf line info
bpf, arm64: Call build_prologue() first in first JIT pass
bpf: Fix issue with bpf preload module taking over stdout/stdin of kernel.
bpftool: Bpf skeletons assert type sizes
bpf: Cleanup comments
...
====================
Link: https://lore.kernel.org/r/20220304164313.31675-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
On x86_64 we must disable preemption before we enable interrupts
for stack faults, int3 and debugging, because the current task is using
a per CPU debug stack defined by the IST. If we schedule out, another task
can come in and use the same stack and cause the stack to be corrupted
and crash the kernel on return.
When CONFIG_PREEMPT_RT is enabled, spinlock_t locks become sleeping, and
one of these is the spin lock used in signal handling.
Some of the debug code (int3) causes do_trap() to send a signal.
This function calls a spinlock_t lock that has been converted to a
sleeping lock. If this happens, the above issues with the corrupted
stack is possible.
Instead of calling the signal right away, for PREEMPT_RT and x86,
the signal information is stored on the stacks task_struct and
TIF_NOTIFY_RESUME is set. Then on exit of the trap, the signal resume
code will send the signal when preemption is enabled.
[ rostedt: Switched from #ifdef CONFIG_PREEMPT_RT to
ARCH_RT_DELAYS_SIGNAL_SEND and added comments to the code. ]
[bigeasy: Add on 32bit as per Yang Shi, minor rewording. ]
[ tglx: Use a config option ]
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/Ygq5aBB/qMQw6aP5@linutronix.de
On do_jit failure path, the header is freed by bpf_jit_binary_pack_free.
While bpf_jit_binary_pack_free doesn't require proper ro_header->size,
bpf_prog_pack_free still uses it. Set header->size in bpf_int_jit_compile
before calling bpf_jit_binary_pack_free.
Fixes: 1022a5498f ("bpf, x86_64: Use bpf_jit_binary_pack_alloc")
Fixes: 33c9805860 ("bpf: Introduce bpf_jit_binary_pack_[alloc|finalize|free]")
Reported-by: Kui-Feng Lee <kuifeng@fb.com>
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220302175126.247459-3-song@kernel.org
kernel test robot reported kernel BUG like:
[ 44.587744][ T1] kernel BUG at arch/x86/mm/physaddr.c:76!
[ 44.590151][ T1] __vmalloc_area_node (mm/vmalloc.c:622 mm/vmalloc.c:2995)
[ 44.590151][ T1] __vmalloc_node_range (mm/vmalloc.c:3108)
[ 44.590151][ T1] __vmalloc_node (mm/vmalloc.c:3157)
which is triggered with HAVE_ARCH_HUGE_VMALLOC on 32-bit x86. Since BPF
only uses HAVE_ARCH_HUGE_VMALLOC for x86_64, turn it off for 32-bit x86.
Fixes: fac54e2bfb ("x86/Kconfig: Select HAVE_ARCH_HUGE_VMALLOC with HAVE_ARCH_HUGE_VMAP")
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220302175126.247459-2-song@kernel.org
kvm_arch_vcpu_ioctl_run is already doing srcu_read_lock/unlock in two
places, namely vcpu_run and post_kvm_run_save, and a third is actually
needed around the call to vcpu->arch.complete_userspace_io to avoid
the following splat:
WARNING: suspicious RCU usage
arch/x86/kvm/pmu.c:190 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
1 lock held by CPU 28/KVM/370841:
#0: ff11004089f280b8 (&vcpu->mutex){+.+.}-{3:3}, at: kvm_vcpu_ioctl+0x87/0x730 [kvm]
Call Trace:
<TASK>
dump_stack_lvl+0x59/0x73
reprogram_fixed_counter+0x15d/0x1a0 [kvm]
kvm_pmu_trigger_event+0x1a3/0x260 [kvm]
? free_moved_vector+0x1b4/0x1e0
complete_fast_pio_in+0x8a/0xd0 [kvm]
This splat is not at all unexpected, since complete_userspace_io callbacks
can execute similar code to vmexits. For example, SVM with nrips=false
will call into the emulator from svm_skip_emulated_instruction().
While it's tempting to never acquire kvm->srcu for an uninitialized vCPU,
practically speaking there's no penalty to acquiring kvm->srcu "early"
as the KVM_MP_STATE_UNINITIALIZED path is a one-time thing per vCPU. On
the other hand, seemingly innocuous helpers like kvm_apic_accept_events()
and sync_regs() can theoretically reach code that might access
SRCU-protected data structures, e.g. sync_regs() can trigger forced
existing of nested mode via kvm_vcpu_ioctl_x86_set_vcpu_events().
Reported-by: Like Xu <likexu@tencent.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Just like on the optional mmu_alloc_direct_roots() path, once shadow
path reaches "r = -EIO" somewhere, the caller needs to know the actual
state in order to enter error handling and avoid something worse.
Fixes: 4a38162ee9 ("KVM: MMU: load PDPTRs outside mmu_lock")
Signed-off-by: Like Xu <likexu@tencent.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220301124941.48412-1-likexu@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Recent Fam19h EPYC server line of processors from AMD support system
management functionality via HSMP (Host System Management Port) interface.
The Host System Management Port (HSMP) is an interface to provide
OS-level software with access to system management functions via a
set of mailbox registers.
More details on the interface can be found in chapter
"7 Host System Management Port (HSMP)" of the following PPR
https://www.amd.com/system/files/TechDocs/55898_B1_pub_0.50.zip
This patch adds new amd_hsmp module under the drivers/platforms/x86/
which creates miscdevice with an IOCTL interface to the user space.
/dev/hsmp is for running the hsmp mailbox commands.
Signed-off-by: Suma Hegde <suma.hegde@amd.com>
Signed-off-by: Naveen Krishna Chatradhi <nchatrad@amd.com>
Reviewed-by: Carlos Bilbao <carlos.bilbao@amd.com>
Acked-by: Song Liu <song@kernel.org>
Reviewed-by: Nathan Fontenot <nathan.fontenot@amd.com>
Link: https://lore.kernel.org/r/20220222050501.18789-1-nchatrad@amd.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
second patch was supposed to fix the first, but in reality it was
just as broken, so both have to go.
x86 host:
* Revert incorrect assumption that cr3 changes come with preempt notifier
callbacks (they don't when static branches are changed, for example)
ARM host:
* Correctly synchronise PMR and co on PSCI CPU_SUSPEND
* Skip tests that depend on GICv3 when the HW isn't available
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull kvm fixes from Paolo Bonzini:
"The bigger part of the change is a revert for x86 hosts. Here the
second patch was supposed to fix the first, but in reality it was just
as broken, so both have to go.
x86 host:
- Revert incorrect assumption that cr3 changes come with preempt
notifier callbacks (they don't when static branches are changed,
for example)
ARM host:
- Correctly synchronise PMR and co on PSCI CPU_SUSPEND
- Skip tests that depend on GICv3 when the HW isn't available"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: selftests: aarch64: Skip tests if we can't create a vgic-v3
Revert "KVM: VMX: Save HOST_CR3 in vmx_prepare_switch_to_guest()"
Revert "KVM: VMX: Save HOST_CR3 in vmx_set_host_fs_gs()"
KVM: arm64: Don't miss pending interrupts for suspended vCPU
Disable preemption when loading/putting the AVIC during an APICv refresh.
If the vCPU task is preempted and migrated ot a different pCPU, the
unprotected avic_vcpu_load() could set the wrong pCPU in the physical ID
cache/table.
Pull the necessary code out of avic_vcpu_{,un}blocking() and into a new
helper to reduce the probability of introducing this exact bug a third
time.
Fixes: df7e4827c5 ("KVM: SVM: call avic_vcpu_load/avic_vcpu_put when enabling/disabling AVIC")
Cc: stable@vger.kernel.org
Reported-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This expands generic branch type classification by adding two more entries
there in i.e irq and exception return. Also updates the x86 implementation
to process X86_BR_IRET and X86_BR_IRQ records as appropriate. This changes
branch types reported to user space on x86 platform but it should not be a
problem. The possible scenarios and impacts are enumerated here.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/1645681014-3346-1-git-send-email-anshuman.khandual@arm.com
Support 64-bit BAR size for discovery, and do not truncate return from
generic_uncore_mmio_box_ctl() to 32 bits.
Signed-off-by: Steve Wahl <steve.wahl@hpe.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/20220218175418.421268-1-steve.wahl@hpe.com
Exit to userspace if setup_vmgexit_scratch() fails due to OOM or because
copying data from guest (userspace) memory failed/faulted. The OOM
scenario is clearcut, it's userspace's decision as to whether it should
terminate the guest, free memory, etc...
As for -EFAULT, arguably, any guest issue is a violation of the guest's
contract with userspace, and thus userspace needs to decide how to
proceed. E.g. userspace defines what is RAM vs. MMIO and communicates
that directly to the guest, KVM is not involved in deciding what is/isn't
RAM nor in communicating that information to the guest. If the scratch
GPA doesn't resolve to a memslot, then the guest is not honoring the
memory configuration as defined by userspace.
And if userspace unmaps an hva for whatever reason, then exiting to
userspace with -EFAULT is absolutely the right thing to do. KVM's ABI
currently sucks and doesn't provide enough information to act on the
-EFAULT, but that will hopefully be remedied in the future as there are
multiple use cases, e.g. uffd and virtiofs truncation, that shouldn't
require any work in KVM beyond returning -EFAULT with a small amount of
metadata.
KVM could define its ABI such that failure to access the scratch area is
reflected into the guest, i.e. establish a contract with userspace, but
that's undesirable as it limits KVM's options in the future, e.g. in the
potential uffd case any failure on a uaccess needs to kick out to
userspace. KVM does have several cases where it reflects these errors
into the guest, e.g. kvm_pv_clock_pairing() and Hyper-V emulation, but
KVM would preferably "fix" those instead of propagating the falsehood
that any memory failure is the guest's fault.
Lastly, returning a boolean as an "error" for that a helper that isn't
named accordingly never works out well.
Fixes: ad5b353240 ("KVM: SVM: Do not terminate SEV-ES guests on GHCB validation failure")
Cc: Alper Gun <alpergun@google.com>
Cc: Peter Gonda <pgonda@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220225205209.3881130-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
WARN and bail if is_unsync_root() is passed a root for which there is no
shadow page, i.e. is passed the physical address of one of the special
roots, which do not have an associated shadow page. The current usage
squeaks by without bug reports because neither kvm_mmu_sync_roots() nor
kvm_mmu_sync_prev_roots() calls the helper with pae_root or pml4_root,
and 5-level AMD CPUs are not generally available, i.e. no one can coerce
KVM into calling is_unsync_root() on pml5_root.
Note, this doesn't fix the mess with 5-level nNPT, it just (hopefully)
prevents KVM from crashing.
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220225182248.3812651-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Zap only obsolete roots when responding to zapping a single root shadow
page. Because KVM keeps root_count elevated when stuffing a previous
root into its PGD cache, shadowing a 64-bit guest means that zapping any
root causes all vCPUs to reload all roots, even if their current root is
not affected by the zap.
For many kernels, zapping a single root is a frequent operation, e.g. in
Linux it happens whenever an mm is dropped, e.g. process exits, etc...
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220225182248.3812651-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Remove the generic kvm_reload_remote_mmus() and open code its
functionality into the two x86 callers. x86 is (obviously) the only
architecture that uses the hook, and is also the only architecture that
uses KVM_REQ_MMU_RELOAD in a way that's consistent with the name. That
will change in a future patch, as x86's usage when zapping a single
shadow page x86 doesn't actually _need_ to reload all vCPUs' MMUs, only
MMUs whose root is being zapped actually need to be reloaded.
s390 also uses KVM_REQ_MMU_RELOAD, but for a slightly different purpose.
Drop the generic code in anticipation of implementing s390 and x86 arch
specific requests, which will allow dropping KVM_REQ_MMU_RELOAD entirely.
Opportunistically reword the x86 TDP MMU comment to avoid making
references to functions (and requests!) when possible, and to remove the
rather ambiguous "this".
No functional change intended.
Cc: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220225182248.3812651-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Replace a KVM_REQ_MMU_RELOAD request with a direct kvm_mmu_unload() call
when the guest's CR4.PCIDE changes. This will allow tweaking the logic
of KVM_REQ_MMU_RELOAD to free only obsolete/invalid roots, which is the
historical intent of KVM_REQ_MMU_RELOAD. The recent PCIDE behavior is
the only user of KVM_REQ_MMU_RELOAD that doesn't mark affected roots as
obsolete, needs to unconditionally unload the entire MMU, _and_ affects
only the current vCPU.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220225182248.3812651-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Outer-privilege level return is not implemented in emulator,
move the unhandled logic into __load_segment_descriptor to
make it easier to understand why the checks for RET are
incomplete.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Message-Id: <5b7188e6388ac9f4567d14eab32db9adf3e00119.1644292363.git.houwenlong.hwl@antgroup.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Code segment descriptor can be loaded by jmp/call/ret, iret
and int. The privilege checks are different between those
instructions above realmode. Although, the emulator has
use x86_transfer_type enumerate to differentiate them, but
it is not really used in __load_segment_descriptor(). Note,
far jump/call to call gate, task gate or task state segment
are not implemented in emulator.
As for far jump/call to code segment, if DPL > CPL for conforming
code or (RPL > CPL or DPL != CPL) for non-conforming code, it
should trigger #GP. The current checks are ok.
As for far return, if RPL < CPL or DPL > RPL for conforming
code or DPL != RPL for non-conforming code, it should trigger #GP.
Outer level return is not implemented above virtual-8086 mode in
emulator. So it implies that RPL <= CPL, but the current checks
wouldn't trigger #GP if RPL < CPL.
As for code segment loading in task switch, if DPL > RPL for conforming
code or DPL != RPL for non-conforming code, it should trigger #TS. Since
segment selector is loaded before segment descriptor when load state from
tss, it implies that RPL = CPL, so the current checks are ok.
The only problem in current implementation is missing RPL < CPL check for
far return. However, change code to follow the manual is better.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Message-Id: <e01f5ea70fc1f18f23da1182acdbc5c97c0e5886.1644292363.git.houwenlong.hwl@antgroup.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Per Intel's SDM on the "Instruction Set Reference", when
loading segment descriptor, not-present segment check should
be after all type and privilege checks. But the emulator checks
it first, then #NP is triggered instead of #GP if privilege fails
and segment is not present. Put not-present segment check after
type and privilege checks in __load_segment_descriptor().
Fixes: 38ba30ba51 (KVM: x86 emulator: Emulate task switch in emulator.c)
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Message-Id: <52573c01d369f506cadcf7233812427cf7db81a7.1644292363.git.houwenlong.hwl@antgroup.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Hide the lapic's "raw" write helper inside lapic.c to force non-APIC code
to go through proper helpers when modification the vAPIC state. Keep the
read helper visible to outsiders for now, refactoring KVM to hide it too
is possible, it will just take more work to do so.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220204214205.3306634-11-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Emulate the x2APIC ICR as a single 64-bit register, as opposed to forking
it across ICR and ICR2 as two 32-bit registers. This mirrors hardware
behavior for Intel's upcoming IPI virtualization support, which does not
split the access.
Previous versions of Intel's SDM and AMD's APM don't explicitly state
exactly how ICR is reflected in the vAPIC page for x2APIC, KVM just
happened to speculate incorrectly.
Handling the upcoming behavior is necessary in order to maintain
backwards compatibility with KVM_{G,S}ET_LAPIC, e.g. failure to shuffle
the 64-bit ICR to ICR+ICR2 and vice versa would break live migration if
IPI virtualization support isn't symmetrical across the source and dest.
Cc: Zeng Guang <guang.zeng@intel.com>
Cc: Chao Gao <chao.gao@intel.com>
Cc: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220204214205.3306634-10-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add helpers to handle 64-bit APIC read/writes via MSRs to deduplicate the
x2APIC and Hyper-V code needed to service reads/writes to ICR. Future
support for IPI virtualization will add yet another path where KVM must
handle 64-bit APIC MSR reads/write (to ICR).
Opportunistically fix the comment in the write path; ICR2 holds the
destination (if there's no shorthand), not the vector.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220204214205.3306634-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Make the low level read/write lapic helpers static, any accesses to the
local APIC from vendor code or non-APIC code should be routed through
proper helpers.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220204214205.3306634-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
WARN if KVM emulates an IPI without clearing the BUSY flag, failure to do
so could hang the guest if it waits for the IPI be sent.
Opportunistically use APIC_ICR_BUSY macro instead of open coding the
magic number, and add a comment to clarify why kvm_recalculate_apic_map()
is unconditionally invoked (it's really, really confusing for IPIs due to
the existence of fast paths that don't trigger a potential recalc).
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220204214205.3306634-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Don't bother rewriting the ICR value into the vAPIC page on an AVIC IPI
virtualization failure, the access is a trap, i.e. the value has already
been written to the vAPIC page. The one caveat is if hardware left the
BUSY flag set (which appears to happen somewhat arbitrarily), in which
case go through the "nodecode" APIC-write path in order to clear the BUSY
flag.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220204214205.3306634-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Use the common kvm_apic_write_nodecode() to handle AVIC/APIC-write traps
instead of open coding the same exact code. This will allow making the
low level lapic helpers inaccessible outside of lapic.c code.
Opportunistically clean up the params to eliminate a bunch of svm=>vcpu
reflection.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220204214205.3306634-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Use the "raw" helper to read the vAPIC register after an APIC-write trap
VM-Exit. Hardware is responsible for vetting the write, and the caller
is responsible for sanitizing the offset. This is a functional change,
as it means KVM will consume whatever happens to be in the vAPIC page if
the write was dropped by hardware. But, unless userspace deliberately
wrote garbage into the vAPIC page via KVM_SET_LAPIC, the value should be
zero since it's not writable by the guest.
This aligns common x86 with SVM's AVIC logic, i.e. paves the way for
using the nodecode path to handle APIC-write traps when AVIC is enabled.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220204214205.3306634-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Move the vAPIC offset adjustments done in the APIC-write trap path from
common x86 to VMX in anticipation of using the nodecode path for SVM's
AVIC. The adjustment reflects hardware behavior, i.e. it's technically a
property of VMX, no common x86. SVM's AVIC behavior is identical, so
it's a bit of a moot point, the goal is purely to make it easier to
understand why the adjustment is ok.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220204214205.3306634-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Emulating writes to SELF_IPI with a write to ICR has an unwanted side effect:
the value of ICR in vAPIC page gets changed. The lists SELF_IPI as write-only,
with no associated MMIO offset, so any write should have no visible side
effect in the vAPIC page.
Reported-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
In emulation of writing to cr8, one of the lowest four bits in TPR[3:0]
is kept.
According to Intel SDM 10.8.6.1(baremetal scenario):
"APIC.TPR[bits 7:4] = CR8[bits 3:0], APIC.TPR[bits 3:0] = 0";
and SDM 28.3(use TPR shadow):
"MOV to CR8. The instruction stores bits 3:0 of its source operand into
bits 7:4 of VTPR; the remainder of VTPR (bits 3:0 and bits 31:8) are
cleared.";
and AMD's APM 16.6.4:
"Task Priority Sub-class (TPS)-Bits 3 : 0. The TPS field indicates the
current sub-priority to be used when arbitrating lowest-priority messages.
This field is written with zero when TPR is written using the architectural
CR8 register.";
so in KVM emulated scenario, clear TPR[3:0] to make a consistent behavior
as in other scenarios.
This doesn't impact evaluation and delivery of pending virtual interrupts
because processor does not use the processor-priority sub-class to
determine which interrupts to delivery and which to inhibit.
Sub-class is used by hardware to arbitrate lowest priority interrupts,
but KVM just does a round-robin style delivery.
Fixes: b93463aa59 ("KVM: Accelerated apic support")
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220210094506.20181-1-zhenzhong.duan@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
For both CR0 and CR4, disassociate the TLB flush logic from the
MMU role logic. Instead of relying on kvm_mmu_reset_context() being
a superset of various TLB flushes (which is not necessarily going to
be the case in the future), always call it if the role changes
but also set the various TLB flush requests according to what is
in the manual.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
AMD retpoline may be susceptible to speculation. The speculation
execution window for an incorrect indirect branch prediction using
LFENCE/JMP sequence may potentially be large enough to allow
exploitation using Spectre V2.
By default, don't use retpoline,lfence on AMD. Instead, use the
generic retpoline.
Signed-off-by: Kim Phillips <kim.phillips@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
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Backmerge tag 'v5.17-rc6' into drm-next
This backmerges v5.17-rc6 so I can merge some amdgpu and some tegra changes on top.
Signed-off-by: Dave Airlie <airlied@redhat.com>
In Kconfig, inside the "Processor type and features" menu, there is
the CONFIG_I8K option: "Dell i8k legacy laptop support". This is
very confusing - enabling CONFIG_I8K is not required for the kernel to
support old Dell laptops. This option is specific to the dell-smm-hwmon
driver, which mostly exports some hardware monitoring information and
allows the user to change fan speed.
This option is misplaced, so move CONFIG_I8K to drivers/hwmon/Kconfig,
where it belongs.
Also, modify the dependency order - change
select SENSORS_DELL_SMM
to
depends on SENSORS_DELL_SMM
as it is just a configuration option of dell-smm-hwmon. This includes
changing the option type from tristate to bool. It was tristate because
it could select CONFIG_SENSORS_DELL_SMM=m .
When running "make oldconfig" on configurations with
CONFIG_SENSORS_DELL_SMM enabled , this change will result in an
additional question (which could be printed several times during
bisecting). I think that tidying up the configuration is worth it,
though.
Next patch tweaks the description of CONFIG_I8K.
Signed-off-by: Mateusz Jończyk <mat.jonczyk@o2.pl>
Cc: Pali Rohár <pali@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jean Delvare <jdelvare@suse.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Mark Gross <markgross@kernel.org>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220212125654.357408-1-mat.jonczyk@o2.pl
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
One of the things that CONFIG_HARDENED_USERCOPY sanity-checks is whether
an object that is about to be copied to/from userspace is overlapping
the stack at all. If it is, it performs a number of inexpensive
bounds checks. One of the finer-grained checks is whether an object
crosses stack frames within the stack region. Doing this on x86 with
CONFIG_FRAME_POINTER was cheap/easy. Doing it with ORC was deemed too
heavy, and was left out (a while ago), leaving the courser whole-stack
check.
The LKDTM tests USERCOPY_STACK_FRAME_TO and USERCOPY_STACK_FRAME_FROM
try to exercise these cross-frame cases to validate the defense is
working. They have been failing ever since ORC was added (which was
expected). While Muhammad was investigating various LKDTM failures[1],
he asked me for additional details on them, and I realized that when
exact stack frame boundary checking is not available (i.e. everything
except x86 with FRAME_POINTER), it could check if a stack object is at
least "current depth valid", in the sense that any object within the
stack region but not between start-of-stack and current_stack_pointer
should be considered unavailable (i.e. its lifetime is from a call no
longer present on the stack).
Introduce ARCH_HAS_CURRENT_STACK_POINTER to track which architectures
have actually implemented the common global register alias.
Additionally report usercopy bounds checking failures with an offset
from current_stack_pointer, which may assist with diagnosing failures.
The LKDTM USERCOPY_STACK_FRAME_TO and USERCOPY_STACK_FRAME_FROM tests
(once slightly adjusted in a separate patch) pass again with this fixed.
[1] https://github.com/kernelci/kernelci-project/issues/84
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Reported-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
v1: https://lore.kernel.org/lkml/20220216201449.2087956-1-keescook@chromium.org
v2: https://lore.kernel.org/lkml/20220224060342.1855457-1-keescook@chromium.org
v3: https://lore.kernel.org/lkml/20220225173345.3358109-1-keescook@chromium.org
v4: - improve commit log (akpm)
When sending a call-function IPI-many to vCPUs, yield to the
IPI target vCPU which is marked as preempted.
but when emulating HLT, an idling vCPU will be voluntarily
scheduled out and mark as preempted from the guest kernel
perspective. yielding to idle vCPU is pointless and increase
unnecessary vmexit, maybe miss the true preempted vCPU
so yield to IPI target vCPU only if vCPU is busy and preempted
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Message-Id: <1644380201-29423-1-git-send-email-lirongqing@baidu.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When Linux runs as an Isolated VM on Hyper-V, it supports AMD SEV-SNP
but it's partially enlightened, i.e. cc_platform_has(
CC_ATTR_GUEST_MEM_ENCRYPT) is true but sev_active() is false.
Commit 4d96f91091 per se is good, but with it now
kvm_setup_vsyscall_timeinfo() -> kvmclock_init_mem() calls
set_memory_decrypted(), and later gets stuck when trying to zere out
the pages pointed by 'hvclock_mem', if Linux runs as an Isolated VM on
Hyper-V. The cause is that here now the Linux VM should no longer access
the original guest physical addrss (GPA); instead the VM should do
memremap() and access the original GPA + ms_hyperv.shared_gpa_boundary:
see the example code in drivers/hv/connection.c: vmbus_connect() or
drivers/hv/ring_buffer.c: hv_ringbuffer_init(). If the VM tries to
access the original GPA, it keepts getting injected a fault by Hyper-V
and gets stuck there.
Here the issue happens only when the VM has >=65 vCPUs, because the
global static array hv_clock_boot[] can hold 64 "struct
pvclock_vsyscall_time_info" (the sizeof of the struct is 64 bytes), so
kvmclock_init_mem() only allocates memory in the case of vCPUs > 64.
Since the 'hvclock_mem' pages are only useful when the kvm clock is
supported by the underlying hypervisor, fix the issue by returning
early when Linux VM runs on Hyper-V, which doesn't support kvm clock.
Fixes: 4d96f91091 ("x86/sev: Replace occurrences of sev_active() with cc_platform_has()")
Tested-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Message-Id: <20220225084600.17817-1-decui@microsoft.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Even if "no-kvmclock" is passed in cmdline parameter, the guest kernel
still allocates hvclock_mem which is scaled by the number of vCPUs,
let's check kvmclock enable in advance to avoid this memory waste.
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1645520523-30814-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
MWAIT is advertised in host is not overcommitted scenario, however, PV
TLB/sched yield should be enabled in host overcommitted scenario. Let's
add the MWAIT checking when enabling PV TLB/sched yield.
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1645777780-2581-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
For cleanliness, do not leave a stale GVA in the cache after all the roots are
cleared. In practice, kvm_mmu_load will go through kvm_mmu_sync_roots if
paging is on, and will not use vcpu_match_mmio_gva at all if paging is off.
However, leaving data in the cache might cause bugs in the future.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Since the guest PGD is now loaded after the MMU has been set up
completely, the desired role for a cache hit is simply the current
mmu_role. There is no need to compute it again, so __kvm_mmu_new_pgd
can be folded in kvm_mmu_new_pgd.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Now that __kvm_mmu_new_pgd does not look at the MMU's root_level and
shadow_root_level anymore, pull the PGD load after the initialization of
the shadow MMUs.
Besides being more intuitive, this enables future simplifications
and optimizations because it's not necessary anymore to compute the
role outside kvm_init_mmu. In particular, kvm_mmu_reset_context was not
attempting to use a cached PGD to avoid having to figure out the new role.
With this change, it could follow what nested_{vmx,svm}_load_cr3 are doing,
and avoid unloading all the cached roots.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Right now, PGD caching avoids placing a PAE root in the cache by using the
old value of mmu->root_level and mmu->shadow_root_level; it does not look
for a cached PGD if the old root is a PAE one, and then frees it using
kvm_mmu_free_roots.
Change the logic instead to free the uncacheable root early.
This way, __kvm_new_mmu_pgd is able to look up the cache when going from
32-bit to 64-bit (if there is a hit, the invalid root becomes the least
recently used). An example of this is nested virtualization with shadow
paging, when a 64-bit L1 runs a 32-bit L2.
As a side effect (which is actually the reason why this patch was
written), PGD caching does not use the old value of mmu->root_level
and mmu->shadow_root_level anymore.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
These functions only operate on a given MMU, of which there is more
than one in a vCPU (we care about two, because the third does not have
any roots and is only used to walk guest page tables). They do need a
struct kvm in order to lock the mmu_lock, but they do not needed anything
else in the struct kvm_vcpu. So, pass the vcpu->kvm directly to them.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Right now, PGD caching requires a complicated dance of first computing
the MMU role and passing it to __kvm_mmu_new_pgd(), and then separately calling
kvm_init_mmu().
Part of this is due to kvm_mmu_free_roots using mmu->root_level and
mmu->shadow_root_level to distinguish whether the page table uses a single
root or 4 PAE roots. Because kvm_init_mmu() can overwrite mmu->root_level,
kvm_mmu_free_roots() must be called before kvm_init_mmu().
However, even after kvm_init_mmu() there is a way to detect whether the
page table may hold PAE roots, as root.hpa isn't backed by a shadow when
it points at PAE roots. Using this method results in simpler code, and
is one less obstacle in moving all calls to __kvm_mmu_new_pgd() after the
MMU has been initialized.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The root_hpa and root_pgd fields form essentially a struct kvm_mmu_root_info.
Use the struct to have more consistency between mmu->root and
mmu->prev_roots.
The patch is entirely search and replace except for cached_root_available,
which does not need a temporary struct kvm_mmu_root_info anymore.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
WARN and bail if KVM attempts to free a root that isn't backed by a shadow
page. KVM allocates a bare page for "special" roots, e.g. when using PAE
paging or shadowing 2/3/4-level page tables with 4/5-level, and so root_hpa
will be valid but won't be backed by a shadow page. It's all too easy to
blindly call mmu_free_root_page() on root_hpa, be nice and WARN instead of
crashing KVM and possibly the kernel.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Enabling async page faults is nonsensical if paging is disabled, but
it is allowed because CR0.PG=0 does not clear the async page fault
MSR. Just ignore them and only use the artificial halt state,
similar to what happens in guest mode if async #PF vmexits are disabled.
Given the increasingly complex logic, and the nicer code if the new
"if" is placed last, opportunistically change the "||" into a chain
of "if (...) return false" statements.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
While the guest runs, EFER.LME cannot change unless CR0.PG is clear, and
therefore EFER.NX is the only bit that can affect the MMU role. However,
set_efer accepts a host-initiated change to EFER.LME even with CR0.PG=1.
In that case, the MMU has to be reset.
Fixes: 11988499e6 ("KVM: x86: Skip EFER vs. guest CPUID checks for host-initiated writes")
Cc: stable@vger.kernel.org
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add a new capability, KVM_CAP_PMU_CAPABILITY, that takes a bitmask of
settings/features to allow userspace to configure PMU virtualization on
a per-VM basis. For now, support a single flag, KVM_PMU_CAP_DISABLE,
to allow disabling PMU virtualization for a VM even when KVM is configured
with enable_pmu=true a module level.
To keep KVM simple, disallow changing VM's PMU configuration after vCPUs
have been created.
Signed-off-by: David Dunn <daviddunn@google.com>
Message-Id: <20220223225743.2703915-2-daviddunn@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Cast kvm_x86_ops.func to 'void *' when updating KVM static calls that are
conditionally patched to __static_call_return0(). clang complains about
using mismatching pointers in the ternary operator, which breaks the
build when compiling with CONFIG_KVM_WERROR=y.
>> arch/x86/include/asm/kvm-x86-ops.h:82:1: warning: pointer type mismatch
('bool (*)(struct kvm_vcpu *)' and 'void *') [-Wpointer-type-mismatch]
Fixes: 5be2226f41 ("KVM: x86: allow defining return-0 static calls")
Reported-by: Like Xu <like.xu.linux@gmail.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: David Dunn <daviddunn@google.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Message-Id: <20220223162355.3174907-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
From: Peng Hao <flyingpeng@tencent.com>
Remove a redundant 'cpu' declaration from inside an if-statement that
that shadows an identical declaration at function scope. Both variables
are used as scratch variables in for_each_*_cpu() loops, thus there's no
harm in sharing a variable.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peng Hao <flyingpeng@tencent.com>
Message-Id: <20220222103954.70062-1-flyingpeng@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Fix a comment documenting the memory barrier related to clearing a
loaded_vmcs; loaded_vmcs tracks the host CPU the VMCS is loaded on via
the field 'cpu', it doesn't have a 'vcpu' field.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peng Hao <flyingpeng@tencent.com>
Message-Id: <20220222104029.70129-1-flyingpeng@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Make sure nested_vmx_hardware_setup/unsetup() are called in pairs under
the same conditions. Calling nested_vmx_hardware_unsetup() when nested
is false "works" right now because it only calls free_page() on zero-
initialized pointers, but it's possible that more code will be added to
nested_vmx_hardware_unsetup() in the future.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peng Hao <flyingpeng@tencent.com>
Message-Id: <20220222104054.70286-1-flyingpeng@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
It has been proven on practice that at least Windows Server 2019 tries
using HVCALL_SEND_IPI_EX in 'XMM fast' mode when it has more than 64 vCPUs
and it needs to send an IPI to a vCPU > 63. Similarly to other XMM Fast
hypercalls (HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE}{,_EX}), this
information is missing in TLFS as of 6.0b. Currently, KVM returns an error
(HV_STATUS_INVALID_HYPERCALL_INPUT) and Windows crashes.
Note, HVCALL_SEND_IPI is a 'standard' fast hypercall (not 'XMM fast') as
all its parameters fit into RDX:R8 and this is handled by KVM correctly.
Cc: stable@vger.kernel.org # 5.14.x: 3244867af8: KVM: x86: Ignore sparse banks size for an "all CPUs", non-sparse IPI req
Cc: stable@vger.kernel.org # 5.14.x
Fixes: d8f5537a88 ("KVM: hyper-v: Advertise support for fast XMM hypercalls")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220222154642.684285-5-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When TLB flush hypercalls (HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE}_EX are
issued in 'XMM fast' mode, the maximum number of allowed sparse_banks is
not 'HV_HYPERCALL_MAX_XMM_REGISTERS - 1' (5) but twice as many (10) as each
XMM register is 128 bit long and can hold two 64 bit long banks.
Cc: stable@vger.kernel.org # 5.14.x
Fixes: 5974565bc2 ("KVM: x86: kvm_hv_flush_tlb use inputs from XMM registers")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220222154642.684285-4-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
'struct kvm_hv_hcall' has all the required information already,
there's no need to pass 'ex' additionally.
No functional change intended.
Cc: stable@vger.kernel.org # 5.14.x
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220222154642.684285-3-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
'struct kvm_hv_hcall' has all the required information already,
there's no need to pass 'ex' additionally.
No functional change intended.
Cc: stable@vger.kernel.org # 5.14.x
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220222154642.684285-2-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Christoph Hellwig and a few others spent a huge effort on removing
set_fs() from most of the important architectures, but about half the
other architectures were never completed even though most of them don't
actually use set_fs() at all.
I did a patch for microblaze at some point, which turned out to be fairly
generic, and now ported it to most other architectures, using new generic
implementations of access_ok() and __{get,put}_kernel_nocheck().
Three architectures (sparc64, ia64, and sh) needed some extra work,
which I also completed.
* 'set_fs-4' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
uaccess: remove CONFIG_SET_FS
ia64: remove CONFIG_SET_FS support
sh: remove CONFIG_SET_FS support
sparc64: remove CONFIG_SET_FS support
lib/test_lockup: fix kernel pointer check for separate address spaces
uaccess: generalize access_ok()
uaccess: fix type mismatch warnings from access_ok()
arm64: simplify access_ok()
m68k: fix access_ok for coldfire
MIPS: use simpler access_ok()
MIPS: Handle address errors for accesses above CPU max virtual user address
uaccess: add generic __{get,put}_kernel_nofault
nios2: drop access_ok() check from __put_user()
x86: use more conventional access_ok() definition
x86: remove __range_not_ok()
sparc64: add __{get,put}_kernel_nofault()
nds32: fix access_ok() checks in get/put_user
uaccess: fix nios2 and microblaze get_user_8()
uaccess: fix integer overflow on access_ok()
Revert back to refreshing vmcs.HOST_CR3 immediately prior to VM-Enter.
The PCID (ASID) part of CR3 can be bumped without KVM being scheduled
out, as the kernel will switch CR3 during __text_poke(), e.g. in response
to a static key toggling. If switch_mm_irqs_off() chooses a new ASID for
the mm associate with KVM, KVM will do VM-Enter => VM-Exit with a stale
vmcs.HOST_CR3.
Add a comment to explain why KVM must wait until VM-Enter is imminent to
refresh vmcs.HOST_CR3.
The following splat was captured by stashing vmcs.HOST_CR3 in kvm_vcpu
and adding a WARN in load_new_mm_cr3() to fire if a new ASID is being
loaded for the KVM-associated mm while KVM has a "running" vCPU:
static void load_new_mm_cr3(pgd_t *pgdir, u16 new_asid, bool need_flush)
{
struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
...
WARN(vcpu && (vcpu->cr3 & GENMASK(11, 0)) != (new_mm_cr3 & GENMASK(11, 0)) &&
(vcpu->cr3 & PHYSICAL_PAGE_MASK) == (new_mm_cr3 & PHYSICAL_PAGE_MASK),
"KVM is hosed, loading CR3 = %lx, vmcs.HOST_CR3 = %lx", new_mm_cr3, vcpu->cr3);
}
------------[ cut here ]------------
KVM is hosed, loading CR3 = 8000000105393004, vmcs.HOST_CR3 = 105393003
WARNING: CPU: 4 PID: 20717 at arch/x86/mm/tlb.c:291 load_new_mm_cr3+0x82/0xe0
Modules linked in: vhost_net vhost vhost_iotlb tap kvm_intel
CPU: 4 PID: 20717 Comm: stable Tainted: G W 5.17.0-rc3+ #747
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
RIP: 0010:load_new_mm_cr3+0x82/0xe0
RSP: 0018:ffffc9000489fa98 EFLAGS: 00010082
RAX: 0000000000000000 RBX: 8000000105393004 RCX: 0000000000000027
RDX: 0000000000000027 RSI: 00000000ffffdfff RDI: ffff888277d1b788
RBP: 0000000000000004 R08: ffff888277d1b780 R09: ffffc9000489f8b8
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000
R13: ffff88810678a800 R14: 0000000000000004 R15: 0000000000000c33
FS: 00007fa9f0e72700(0000) GS:ffff888277d00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000001001b5003 CR4: 0000000000172ea0
Call Trace:
<TASK>
switch_mm_irqs_off+0x1cb/0x460
__text_poke+0x308/0x3e0
text_poke_bp_batch+0x168/0x220
text_poke_finish+0x1b/0x30
arch_jump_label_transform_apply+0x18/0x30
static_key_slow_inc_cpuslocked+0x7c/0x90
static_key_slow_inc+0x16/0x20
kvm_lapic_set_base+0x116/0x190
kvm_set_apic_base+0xa5/0xe0
kvm_set_msr_common+0x2f4/0xf60
vmx_set_msr+0x355/0xe70 [kvm_intel]
kvm_set_msr_ignored_check+0x91/0x230
kvm_emulate_wrmsr+0x36/0x120
vmx_handle_exit+0x609/0x6c0 [kvm_intel]
kvm_arch_vcpu_ioctl_run+0x146f/0x1b80
kvm_vcpu_ioctl+0x279/0x690
__x64_sys_ioctl+0x83/0xb0
do_syscall_64+0x3b/0xc0
entry_SYSCALL_64_after_hwframe+0x44/0xae
</TASK>
---[ end trace 0000000000000000 ]---
This reverts commit 15ad9762d6.
Fixes: 15ad9762d6 ("KVM: VMX: Save HOST_CR3 in vmx_prepare_switch_to_guest()")
Reported-by: Wanpeng Li <kernellwp@gmail.com>
Cc: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Acked-by: Lai Jiangshan <jiangshanlai@gmail.com>
Message-Id: <20220224191917.3508476-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Undo a nested VMX fix as a step toward reverting the commit it fixed,
15ad9762d6 ("KVM: VMX: Save HOST_CR3 in vmx_prepare_switch_to_guest()"),
as the underlying premise that "host CR3 in the vcpu thread can only be
changed when scheduling" is wrong.
This reverts commit a9f2705ec8.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220224191917.3508476-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
There are many different ways that access_ok() is defined across
architectures, but in the end, they all just compare against the
user_addr_max() value or they accept anything.
Provide one definition that works for most architectures, checking
against TASK_SIZE_MAX for user processes or skipping the check inside
of uaccess_kernel() sections.
For architectures without CONFIG_SET_FS(), this should be the fastest
check, as it comes down to a single comparison of a pointer against a
compile-time constant, while the architecture specific versions tend to
do something more complex for historic reasons or get something wrong.
Type checking for __user annotations is handled inconsistently across
architectures, but this is easily simplified as well by using an inline
function that takes a 'const void __user *' argument. A handful of
callers need an extra __user annotation for this.
Some architectures had trick to use 33-bit or 65-bit arithmetic on the
addresses to calculate the overflow, however this simpler version uses
fewer registers, which means it can produce better object code in the
end despite needing a second (statically predicted) branch.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Mark Rutland <mark.rutland@arm.com> [arm64, asm-generic]
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Stafford Horne <shorne@gmail.com>
Acked-by: Dinh Nguyen <dinguyen@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Nine architectures are still missing __{get,put}_kernel_nofault:
alpha, ia64, microblaze, nds32, nios2, openrisc, sh, sparc32, xtensa.
Add a generic version that lets everything use the normal
copy_{from,to}_kernel_nofault() code based on these, removing the last
use of get_fs()/set_fs() from architecture-independent code.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
The way that access_ok() is defined on x86 is slightly different from
most other architectures, and a bit more complex.
The generic version tends to result in the best output on all
architectures, as it results in single comparison against a constant
limit for calls with a known size.
There are a few callers of __range_not_ok(), all of which use TASK_SIZE
as the limit rather than TASK_SIZE_MAX, but I could not see any reason
for picking this. Changing these to call __access_ok() instead uses the
default limit, but keeps the behavior otherwise.
x86 is the only architecture with a WARN_ON_IN_IRQ() checking
access_ok(), but it's probably best to leave that in place.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
The __range_not_ok() helper is an x86 (and sparc64) specific interface
that does roughly the same thing as __access_ok(), but with different
calling conventions.
Change this to use the normal interface in order for consistency as we
clean up all access_ok() implementations.
This changes the limit from TASK_SIZE to TASK_SIZE_MAX, which Al points
out is the right thing do do here anyway.
The callers have to use __access_ok() instead of the normal access_ok()
though, because on x86 that contains a WARN_ON_IN_IRQ() check that cannot
be used inside of NMI context while tracing.
The check in copy_code() is not needed any more, because this one is
already done by copy_from_user_nmi().
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Suggested-by: Christoph Hellwig <hch@infradead.org>
Link: https://lore.kernel.org/lkml/YgsUKcXGR7r4nINj@zeniv-ca.linux.org.uk/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
* Expose KVM_CAP_ENABLE_CAP since it is supported
* Disable KVM_HC_CLOCK_PAIRING in TSC catchup mode
* Ensure async page fault token is nonzero
* Fix lockdep false negative
* Fix FPU migration regression from the AMX changes
x86 guest:
* Don't use PV TLB/IPI/yield on uniprocessor guests
PPC:
* reserve capability id (topic branch for ppc/kvm)
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull kvm fixes from Paolo Bonzini:
"x86 host:
- Expose KVM_CAP_ENABLE_CAP since it is supported
- Disable KVM_HC_CLOCK_PAIRING in TSC catchup mode
- Ensure async page fault token is nonzero
- Fix lockdep false negative
- Fix FPU migration regression from the AMX changes
x86 guest:
- Don't use PV TLB/IPI/yield on uniprocessor guests
PPC:
- reserve capability id (topic branch for ppc/kvm)"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: x86: nSVM: disallow userspace setting of MSR_AMD64_TSC_RATIO to non default value when tsc scaling disabled
KVM: x86/mmu: make apf token non-zero to fix bug
KVM: PPC: reserve capability 210 for KVM_CAP_PPC_AIL_MODE_3
x86/kvm: Don't use pv tlb/ipi/sched_yield if on 1 vCPU
x86/kvm: Fix compilation warning in non-x86_64 builds
x86/kvm/fpu: Remove kvm_vcpu_arch.guest_supported_xcr0
x86/kvm/fpu: Limit guest user_xfeatures to supported bits of XCR0
kvm: x86: Disable KVM_HC_CLOCK_PAIRING if tsc is in always catchup mode
KVM: Fix lockdep false negative during host resume
KVM: x86: Add KVM_CAP_ENABLE_CAP to x86
If nested tsc scaling is disabled, MSR_AMD64_TSC_RATIO should
never have non default value.
Due to way nested tsc scaling support was implmented in qemu,
it would set this msr to 0 when nested tsc scaling was disabled.
Ignore that value for now, as it causes no harm.
Fixes: 5228eb96a4 ("KVM: x86: nSVM: implement nested TSC scaling")
Cc: stable@vger.kernel.org
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220223115649.319134-1-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
In current async pagefault logic, when a page is ready, KVM relies on
kvm_arch_can_dequeue_async_page_present() to determine whether to deliver
a READY event to the Guest. This function test token value of struct
kvm_vcpu_pv_apf_data, which must be reset to zero by Guest kernel when a
READY event is finished by Guest. If value is zero meaning that a READY
event is done, so the KVM can deliver another.
But the kvm_arch_setup_async_pf() may produce a valid token with zero
value, which is confused with previous mention and may lead the loss of
this READY event.
This bug may cause task blocked forever in Guest:
INFO: task stress:7532 blocked for more than 1254 seconds.
Not tainted 5.10.0 #16
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:stress state:D stack: 0 pid: 7532 ppid: 1409
flags:0x00000080
Call Trace:
__schedule+0x1e7/0x650
schedule+0x46/0xb0
kvm_async_pf_task_wait_schedule+0xad/0xe0
? exit_to_user_mode_prepare+0x60/0x70
__kvm_handle_async_pf+0x4f/0xb0
? asm_exc_page_fault+0x8/0x30
exc_page_fault+0x6f/0x110
? asm_exc_page_fault+0x8/0x30
asm_exc_page_fault+0x1e/0x30
RIP: 0033:0x402d00
RSP: 002b:00007ffd31912500 EFLAGS: 00010206
RAX: 0000000000071000 RBX: ffffffffffffffff RCX: 00000000021a32b0
RDX: 000000000007d011 RSI: 000000000007d000 RDI: 00000000021262b0
RBP: 00000000021262b0 R08: 0000000000000003 R09: 0000000000000086
R10: 00000000000000eb R11: 00007fefbdf2baa0 R12: 0000000000000000
R13: 0000000000000002 R14: 000000000007d000 R15: 0000000000001000
Signed-off-by: Liang Zhang <zhangliang5@huawei.com>
Message-Id: <20220222031239.1076682-1-zhangliang5@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The kernel provides infrastructure to set or clear the encryption mask
from the pages for AMD SEV, but TDX requires few tweaks.
- TDX and SEV have different requirements to the cache and TLB
flushing.
- TDX has own routine to notify VMM about page encryption status change.
Modify __set_memory_enc_pgtable() and make it flexible enough to cover
both AMD SEV and Intel TDX. The AMD-specific behavior is isolated in the
callbacks under x86_platform.guest. TDX will provide own version of said
callbacks.
[ bp: Beat into submission. ]
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Link: https://lore.kernel.org/r/20220223043528.2093214-1-brijesh.singh@amd.com
AMD SME/SEV uses a bit in the page table entries to indicate that the
page is encrypted and not accessible to the VMM.
TDX uses a similar approach, but the polarity of the mask is opposite to
AMD: if the bit is set the page is accessible to VMM.
Provide vendor-neutral API to deal with the mask: cc_mkenc() and
cc_mkdec() modify given address to make it encrypted/decrypted. It can
be applied to phys_addr_t, pgprotval_t or page table entry value.
pgprot_encrypted() and pgprot_decrypted() reimplemented using new
helpers.
The implementation will be extended to cover TDX.
pgprot_decrypted() is used by drivers (i915, virtio_gpu, vfio).
cc_mkdec() called by pgprot_decrypted(). Export cc_mkdec().
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/r/20220222185740.26228-5-kirill.shutemov@linux.intel.com
The kernel derives the confidential computing platform
type it is running as from sme_me_mask on AMD or by using
hv_is_isolation_supported() on HyperV isolation VMs. This detection
process will be more complicated as more platforms get added.
Declare a confidential computing vendor variable explicitly and set it
via cc_set_vendor() on the respective platform.
[ bp: Massage commit message, fixup HyperV check. ]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/r/20220222185740.26228-4-kirill.shutemov@linux.intel.com
Move cc_platform.c to arch/x86/coco/. The directory is going to be the
home space for code related to confidential computing.
Intel TDX code will land here. AMD SEV code will also eventually be
moved there.
No functional changes.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/r/20220222185740.26228-3-kirill.shutemov@linux.intel.com
There is no need to have struct kernfs_root be part of kernfs.h for
the whole kernel to see and poke around it. Move it internal to kernfs
code and provide a helper function, kernfs_root_to_node(), to handle the
one field that kernfs users were directly accessing from the structure.
Cc: Imran Khan <imran.f.khan@oracle.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220222070713.3517679-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit
623dffb2a2 ("x86/mm/pat: Add set_memory_wt() for Write-Through type")
added it but there were no users.
[ bp: Add a commit message. ]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220223072852.616143-1-hch@lst.de
This is pretty much unused and not really useful. What is more, all
relevant MCA hardware has recoverable machine checks support so there's
no real need to tweak MCA tolerance levels in order to *maybe* extend
machine lifetime.
So rip it out.
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/YcDq8PxvKtTENl/e@zn.tnic
This allows code sharing between fast-headers tree and the vanilla
scheduler tree.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>
This is unused after commit 768db5fee3 ("crypto: x86/des - drop CTR mode implementation")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This is unused after commit c0a64926c5 ("crypto: x86/blowfish - drop CTR mode implementation")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Now that we have SYM_FUNC_ALIAS() and SYM_FUNC_ALIAS_WEAK(), use those
to simplify the definition of function aliases across arch/x86.
For clarity, where there are multiple annotations such as
EXPORT_SYMBOL(), I've tried to keep annotations grouped by symbol. For
example, where a function has a name and an alias which are both
exported, this is organised as:
SYM_FUNC_START(func)
... asm insns ...
SYM_FUNC_END(func)
EXPORT_SYMBOL(func)
SYM_FUNC_ALIAS(alias, func)
EXPORT_SYMBOL(alias)
Where there are only aliases and no exports or other annotations, I have
not bothered with line spacing, e.g.
SYM_FUNC_START(func)
... asm insns ...
SYM_FUNC_END(func)
SYM_FUNC_ALIAS(alias, func)
The tools/perf/ copies of memset_64.S and memset_64.S are updated
likewise to avoid the build system complaining these are mismatched:
| Warning: Kernel ABI header at 'tools/arch/x86/lib/memcpy_64.S' differs from latest version at 'arch/x86/lib/memcpy_64.S'
| diff -u tools/arch/x86/lib/memcpy_64.S arch/x86/lib/memcpy_64.S
| Warning: Kernel ABI header at 'tools/arch/x86/lib/memset_64.S' differs from latest version at 'arch/x86/lib/memset_64.S'
| diff -u tools/arch/x86/lib/memset_64.S arch/x86/lib/memset_64.S
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Mark Brown <broonie@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220216162229.1076788-4-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
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Merge tag 'v5.17-rc5' into sched/core, to resolve conflicts
New conflicts in sched/core due to the following upstream fixes:
44585f7bc0 ("psi: fix "defined but not used" warnings when CONFIG_PROC_FS=n")
a06247c680 ("psi: Fix uaf issue when psi trigger is destroyed while being polled")
Conflicts:
include/linux/psi_types.h
kernel/sched/psi.c
Signed-off-by: Ingo Molnar <mingo@kernel.org>
With unprivileged eBPF enabled, eIBRS (without retpoline) is vulnerable
to Spectre v2 BHB-based attacks.
When both are enabled, print a warning message and report it in the
'spectre_v2' sysfs vulnerabilities file.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Thanks to the chaps at VUsec it is now clear that eIBRS is not
sufficient, therefore allow enabling of retpolines along with eIBRS.
Add spectre_v2=eibrs, spectre_v2=eibrs,lfence and
spectre_v2=eibrs,retpoline options to explicitly pick your preferred
means of mitigation.
Since there's new mitigations there's also user visible changes in
/sys/devices/system/cpu/vulnerabilities/spectre_v2 to reflect these
new mitigations.
[ bp: Massage commit message, trim error messages,
do more precise eIBRS mode checking. ]
Co-developed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Patrick Colp <patrick.colp@oracle.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
The RETPOLINE_AMD name is unfortunate since it isn't necessarily
AMD only, in fact Hygon also uses it. Furthermore it will likely be
sufficient for some Intel processors. Therefore rename the thing to
RETPOLINE_LFENCE to better describe what it is.
Add the spectre_v2=retpoline,lfence option as an alias to
spectre_v2=retpoline,amd to preserve existing setups. However, the output
of /sys/devices/system/cpu/vulnerabilities/spectre_v2 will be changed.
[ bp: Fix typos, massage. ]
Co-developed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
- Handle poisoned pages properly in the SGX reclaimer code
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Merge tag 'x86_urgent_for_v5.17_rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Borislav Petkov:
- Fix the ptrace regset xfpregs_set() callback to behave according to
the ABI
- Handle poisoned pages properly in the SGX reclaimer code
* tag 'x86_urgent_for_v5.17_rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/ptrace: Fix xfpregs_set()'s incorrect xmm clearing
x86/sgx: Fix missing poison handling in reclaimer
A rare kernel panic scenario can happen when the following conditions
are met due to an erratum on fast string copy instructions:
1) An uncorrected error.
2) That error must be in first cache line of a page.
3) Kernel must execute page_copy from the page immediately before that
page.
The fast string copy instructions ("REP; MOVS*") could consume an
uncorrectable memory error in the cache line _right after_ the desired
region to copy and raise an MCE.
Bit 0 of MSR_IA32_MISC_ENABLE can be cleared to disable fast string
copy and will avoid such spurious machine checks. However, that is less
preferable due to the permanent performance impact. Considering memory
poison is rare, it's desirable to keep fast string copy enabled until an
MCE is seen.
Intel has confirmed the following:
1. The CPU erratum of fast string copy only applies to Skylake,
Cascade Lake and Cooper Lake generations.
Directly return from the MCE handler:
2. Will result in complete execution of the "REP; MOVS*" with no data
loss or corruption.
3. Will not result in another MCE firing on the next poisoned cache line
due to "REP; MOVS*".
4. Will resume execution from a correct point in code.
5. Will result in the same instruction that triggered the MCE firing a
second MCE immediately for any other software recoverable data fetch
errors.
6. Is not safe without disabling the fast string copy, as the next fast
string copy of the same buffer on the same CPU would result in a PANIC
MCE.
This should mitigate the erratum completely with the only caveat that
the fast string copy is disabled on the affected hyper thread thus
performance degradation.
This is still better than the OS crashing on MCEs raised on an
irrelevant process due to "REP; MOVS*' accesses in a kernel context,
e.g., copy_page.
Tested:
Injected errors on 1st cache line of 8 anonymous pages of process
'proc1' and observed MCE consumption from 'proc2' with no panic
(directly returned).
Without the fix, the host panicked within a few minutes on a
random 'proc2' process due to kernel access from copy_page.
[ bp: Fix comment style + touch ups, zap an unlikely(), improve the
quirk function's readability. ]
Signed-off-by: Jue Wang <juew@google.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/r/20220218013209.2436006-1-juew@google.com
Where an architecture selects HAVE_STATIC_CALL but not
HAVE_STATIC_CALL_INLINE, each static call has an out-of-line trampoline
which will either branch to a callee or return to the caller.
On such architectures, a number of constraints can conspire to make
those trampolines more complicated and potentially less useful than we'd
like. For example:
* Hardware and software control flow integrity schemes can require the
addition of "landing pad" instructions (e.g. `BTI` for arm64), which
will also be present at the "real" callee.
* Limited branch ranges can require that trampolines generate or load an
address into a register and perform an indirect branch (or at least
have a slow path that does so). This loses some of the benefits of
having a direct branch.
* Interaction with SW CFI schemes can be complicated and fragile, e.g.
requiring that we can recognise idiomatic codegen and remove
indirections understand, at least until clang proves more helpful
mechanisms for dealing with this.
For PREEMPT_DYNAMIC, we don't need the full power of static calls, as we
really only need to enable/disable specific preemption functions. We can
achieve the same effect without a number of the pain points above by
using static keys to fold early returns into the preemption functions
themselves rather than in an out-of-line trampoline, effectively
inlining the trampoline into the start of the function.
For arm64, this results in good code generation. For example, the
dynamic_cond_resched() wrapper looks as follows when enabled. When
disabled, the first `B` is replaced with a `NOP`, resulting in an early
return.
| <dynamic_cond_resched>:
| bti c
| b <dynamic_cond_resched+0x10> // or `nop`
| mov w0, #0x0
| ret
| mrs x0, sp_el0
| ldr x0, [x0, #8]
| cbnz x0, <dynamic_cond_resched+0x8>
| paciasp
| stp x29, x30, [sp, #-16]!
| mov x29, sp
| bl <preempt_schedule_common>
| mov w0, #0x1
| ldp x29, x30, [sp], #16
| autiasp
| ret
... compared to the regular form of the function:
| <__cond_resched>:
| bti c
| mrs x0, sp_el0
| ldr x1, [x0, #8]
| cbz x1, <__cond_resched+0x18>
| mov w0, #0x0
| ret
| paciasp
| stp x29, x30, [sp, #-16]!
| mov x29, sp
| bl <preempt_schedule_common>
| mov w0, #0x1
| ldp x29, x30, [sp], #16
| autiasp
| ret
Any architecture which implements static keys should be able to use this
to implement PREEMPT_DYNAMIC with similar cost to non-inlined static
calls. Since this is likely to have greater overhead than (inlined)
static calls, PREEMPT_DYNAMIC is only defaulted to enabled when
HAVE_PREEMPT_DYNAMIC_CALL is selected.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20220214165216.2231574-6-mark.rutland@arm.com
Currently sched_dynamic_update needs to open-code the enabled/disabled
function names for each preemption model it supports, when in practice
this is a boolean enabled/disabled state for each function.
Make this clearer and avoid repetition by defining the enabled/disabled
states at the function definition, and using helper macros to perform the
static_call_update(). Where x86 currently overrides the enabled
function, it is made to provide both the enabled and disabled states for
consistency, with defaults provided by the core code otherwise.
In subsequent patches this will allow us to support PREEMPT_DYNAMIC
without static calls.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20220214165216.2231574-3-mark.rutland@arm.com
Remove mmu_audit.c and all its collateral, the auditing code has suffered
severe bitrot, ironically partly due to shadow paging being more stable
and thus not benefiting as much from auditing, but mostly due to TDP
supplanting shadow paging for non-nested guests and shadowing of nested
TDP not heavily stressing the logic that is being audited.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
A few vendor callbacks are only used by VMX, but they return an integer
or bool value. Introduce KVM_X86_OP_OPTIONAL_RET0 for them: if a func is
NULL in struct kvm_x86_ops, it will be changed to __static_call_return0
when updating static calls.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
All their invocations are conditional on vcpu->arch.apicv_active,
meaning that they need not be implemented by vendor code: even
though at the moment both vendors implement APIC virtualization,
all of them can be optional. In fact SVM does not need many of
them, and their implementation can be deleted now.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Use the newly corrected KVM_X86_OP annotations to warn about possible
NULL pointer dereferences as soon as the vendor module is loaded.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The original use of KVM_X86_OP_NULL, which was to mark calls
that do not follow a specific naming convention, is not in use
anymore. Instead, let's mark calls that are optional because
they are always invoked within conditionals or with static_call_cond.
Those that are _not_, i.e. those that are defined with KVM_X86_OP,
must be defined by both vendor modules or some kind of NULL pointer
dereference is bound to happen at runtime.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
SVM implements neither update_emulated_instruction nor
set_apic_access_page_addr. Remove an "if" by calling them
with static_call_cond().
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The two ioctls used to implement userspace-accelerated TPR,
KVM_TPR_ACCESS_REPORTING and KVM_SET_VAPIC_ADDR, are available
even if hardware-accelerated TPR can be used. So there is
no reason not to report KVM_CAP_VAPIC.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
xfpregs_set() handles 32-bit REGSET_XFP and 64-bit REGSET_FP. The actual
code treats these regsets as modern FX state (i.e. the beginning part of
XSTATE). The declarations of the regsets thought they were the legacy
i387 format. The code thought they were the 32-bit (no xmm8..15) variant
of XSTATE and, for good measure, made the high bits disappear by zeroing
the wrong part of the buffer. The latter broke ptrace, and everything
else confused anyone trying to understand the code. In particular, the
nonsense definitions of the regsets confused me when I wrote this code.
Clean this all up. Change the declarations to match reality (which
shouldn't change the generated code, let alone the ABI) and fix
xfpregs_set() to clear the correct bits and to only do so for 32-bit
callers.
Fixes: 6164331d15 ("x86/fpu: Rewrite xfpregs_set()")
Reported-by: Luís Ferreira <contact@lsferreira.net>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=215524
Link: https://lore.kernel.org/r/YgpFnZpF01WwR8wU@zn.tnic
For SEV-ES VMs with mirrors to be intra-host migrated they need to be
able to migrate with the mirror. This is due to that fact that all VMSAs
need to be added into the VM with LAUNCH_UPDATE_VMSA before
lAUNCH_FINISH. Allowing migration with mirrors allows users of SEV-ES to
keep the mirror VMs VMSAs during migration.
Adds a list of mirror VMs for the original VM iterate through during its
migration. During the iteration the owner pointers can be updated from
the source to the destination. This fixes the ASID leaking issue which
caused the blocking of migration of VMs with mirrors.
Signed-off-by: Peter Gonda <pgonda@google.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Marc Orr <marcorr@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Message-Id: <20220211193634.3183388-1-pgonda@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Inspired by commit 3553ae5690 (x86/kvm: Don't use pvqspinlock code if
only 1 vCPU), on a VM with only 1 vCPU, there is no need to enable
pv tlb/ipi/sched_yield and we can save the memory for __pv_cpu_mask.
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1645171838-2855-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
On non-x86_64 builds, helpers gtod_is_based_on_tsc() and
kvm_guest_supported_xfd() are defined but never used. Because these are
static inline but are in a .c file, some compilers do warn for them with
-Wunused-function, which becomes an error if -Werror is present.
Add #ifdef so they are only defined in x86_64 builds.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Leonardo Bras <leobras@redhat.com>
Message-Id: <20220218034100.115702-1-leobras@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The SGX reclaimer code lacks page poison handling in its main
free path. This can lead to avoidable machine checks if a
poisoned page is freed and reallocated instead of being
isolated.
A troublesome scenario is:
1. Machine check (#MC) occurs (asynchronous, !MF_ACTION_REQUIRED)
2. arch_memory_failure() is eventually called
3. (SGX) page->poison set to 1
4. Page is reclaimed
5. Page added to normal free lists by sgx_reclaim_pages()
^ This is the bug (poison pages should be isolated on the
sgx_poison_page_list instead)
6. Page is reallocated by some innocent enclave, a second (synchronous)
in-kernel #MC is induced, probably during EADD instruction.
^ This is the fallout from the bug
(6) is unfortunate and can be avoided by replacing the open coded
enclave page freeing code in the reclaimer with sgx_free_epc_page()
to obtain support for poison page handling that includes placing the
poisoned page on the correct list.
Fixes: d6d261bded ("x86/sgx: Add new sgx_epc_page flag bit to mark free pages")
Fixes: 992801ae92 ("x86/sgx: Initial poison handling for dirty and free pages")
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/dcc95eb2aaefb042527ac50d0a50738c7c160dac.1643830353.git.reinette.chatre@intel.com
kvm_vcpu_arch currently contains the guest supported features in both
guest_supported_xcr0 and guest_fpu.fpstate->user_xfeatures field.
Currently both fields are set to the same value in
kvm_vcpu_after_set_cpuid() and are not changed anywhere else after that.
Since it's not good to keep duplicated data, remove guest_supported_xcr0.
To keep the code more readable, introduce kvm_guest_supported_xcr()
and kvm_guest_supported_xfd() to replace the previous usages of
guest_supported_xcr0.
Signed-off-by: Leonardo Bras <leobras@redhat.com>
Message-Id: <20220217053028.96432-3-leobras@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
During host/guest switch (like in kvm_arch_vcpu_ioctl_run()), the kernel
swaps the fpu between host/guest contexts, by using fpu_swap_kvm_fpstate().
When xsave feature is available, the fpu swap is done by:
- xsave(s) instruction, with guest's fpstate->xfeatures as mask, is used
to store the current state of the fpu registers to a buffer.
- xrstor(s) instruction, with (fpu_kernel_cfg.max_features &
XFEATURE_MASK_FPSTATE) as mask, is used to put the buffer into fpu regs.
For xsave(s) the mask is used to limit what parts of the fpu regs will
be copied to the buffer. Likewise on xrstor(s), the mask is used to
limit what parts of the fpu regs will be changed.
The mask for xsave(s), the guest's fpstate->xfeatures, is defined on
kvm_arch_vcpu_create(), which (in summary) sets it to all features
supported by the cpu which are enabled on kernel config.
This means that xsave(s) will save to guest buffer all the fpu regs
contents the cpu has enabled when the guest is paused, even if they
are not used.
This would not be an issue, if xrstor(s) would also do that.
xrstor(s)'s mask for host/guest swap is basically every valid feature
contained in kernel config, except XFEATURE_MASK_PKRU.
Accordingto kernel src, it is instead switched in switch_to() and
flush_thread().
Then, the following happens with a host supporting PKRU starts a
guest that does not support it:
1 - Host has XFEATURE_MASK_PKRU set. 1st switch to guest,
2 - xsave(s) fpu regs to host fpustate (buffer has XFEATURE_MASK_PKRU)
3 - xrstor(s) guest fpustate to fpu regs (fpu regs have XFEATURE_MASK_PKRU)
4 - guest runs, then switch back to host,
5 - xsave(s) fpu regs to guest fpstate (buffer now have XFEATURE_MASK_PKRU)
6 - xrstor(s) host fpstate to fpu regs.
7 - kvm_vcpu_ioctl_x86_get_xsave() copy guest fpstate to userspace (with
XFEATURE_MASK_PKRU, which should not be supported by guest vcpu)
On 5, even though the guest does not support PKRU, it does have the flag
set on guest fpstate, which is transferred to userspace via vcpu ioctl
KVM_GET_XSAVE.
This becomes a problem when the user decides on migrating the above guest
to another machine that does not support PKRU: the new host restores
guest's fpu regs to as they were before (xrstor(s)), but since the new
host don't support PKRU, a general-protection exception ocurs in xrstor(s)
and that crashes the guest.
This can be solved by making the guest's fpstate->user_xfeatures hold
a copy of guest_supported_xcr0. This way, on 7 the only flags copied to
userspace will be the ones compatible to guest requirements, and thus
there will be no issue during migration.
As a bonus, it will also fail if userspace tries to set fpu features
(with the KVM_SET_XSAVE ioctl) that are not compatible to the guest
configuration. Such features will never be returned by KVM_GET_XSAVE
or KVM_GET_XSAVE2.
Also, since kvm_vcpu_after_set_cpuid() now sets fpstate->user_xfeatures,
there is not need to set it in kvm_check_cpuid(). So, change
fpstate_realloc() so it does not touch fpstate->user_xfeatures if a
non-NULL guest_fpu is passed, which is the case when kvm_check_cpuid()
calls it.
Signed-off-by: Leonardo Bras <leobras@redhat.com>
Message-Id: <20220217053028.96432-2-leobras@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
If vcpu has tsc_always_catchup set each request updates pvclock data.
KVM_HC_CLOCK_PAIRING consumers such as ptp_kvm_x86 rely on tsc read on
host's side and do hypercall inside pvclock_read_retry loop leading to
infinite loop in such situation.
v3:
Removed warn
Changed return code to KVM_EFAULT
v2:
Added warn
Signed-off-by: Anton Romanov <romanton@google.com>
Message-Id: <20220216182653.506850-1-romanton@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Follow the precedent set by other architectures that support the VCPU
ioctl, KVM_ENABLE_CAP, and advertise the VM extension, KVM_CAP_ENABLE_CAP.
This way, userspace can ensure that KVM_ENABLE_CAP is available on a
vcpu before using it.
Fixes: 5c919412fe ("kvm/x86: Hyper-V synthetic interrupt controller")
Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Message-Id: <20220214212950.1776943-1-aaronlewis@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
There is a regular need in the kernel to provide a way to declare
having a dynamically sized set of trailing elements in a structure.
Kernel code should always use “flexible array members”[1] for these
cases. The older style of one-element or zero-length arrays should
no longer be used[2].
This code was transformed with the help of Coccinelle:
(next-20220214$ spatch --jobs $(getconf _NPROCESSORS_ONLN) --sp-file script.cocci --include-headers --dir . > output.patch)
@@
identifier S, member, array;
type T1, T2;
@@
struct S {
...
T1 member;
T2 array[
- 0
];
};
UAPI and wireless changes were intentionally excluded from this patch
and will be sent out separately.
[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays
Link: https://github.com/KSPP/linux/issues/78
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
asm/shmbuf.h is currently excluded from the UAPI compile-test because of
the errors like follows:
HDRTEST usr/include/asm/shmbuf.h
In file included from ./usr/include/asm/shmbuf.h:6,
from <command-line>:
./usr/include/asm-generic/shmbuf.h:26:33: error: field ‘shm_perm’ has incomplete type
26 | struct ipc64_perm shm_perm; /* operation perms */
| ^~~~~~~~
./usr/include/asm-generic/shmbuf.h:27:9: error: unknown type name ‘size_t’
27 | size_t shm_segsz; /* size of segment (bytes) */
| ^~~~~~
./usr/include/asm-generic/shmbuf.h:40:9: error: unknown type name ‘__kernel_pid_t’
40 | __kernel_pid_t shm_cpid; /* pid of creator */
| ^~~~~~~~~~~~~~
./usr/include/asm-generic/shmbuf.h:41:9: error: unknown type name ‘__kernel_pid_t’
41 | __kernel_pid_t shm_lpid; /* pid of last operator */
| ^~~~~~~~~~~~~~
The errors can be fixed by replacing size_t with __kernel_size_t and by
including proper headers.
Then, remove the no-header-test entry from user/include/Makefile.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
linux/signal.h and asm/signal.h are currently excluded from the UAPI
compile-test because of the errors like follows:
HDRTEST usr/include/asm/signal.h
In file included from <command-line>:
./usr/include/asm/signal.h:103:9: error: unknown type name ‘size_t’
103 | size_t ss_size;
| ^~~~~~
The errors can be fixed by replacing size_t with __kernel_size_t.
Then, remove the no-header-test entries from user/include/Makefile.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Currently, the SME CPU feature flag is reflective of whether the CPU
supports the feature but not whether it has been activated by the
kernel.
Change this around to clear the SME feature flag if the kernel is not
using it so userspace can determine if it is available and in use
from /proc/cpuinfo.
As the feature flag is cleared on systems where SME isn't active, use
CPUID 0x8000001f to confirm SME availability before calling
native_wbinvd().
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/r/20220216034446.2430634-1-mario.limonciello@amd.com
Refer to housekeeping APIs using single feature types instead of flags.
This prevents from passing multiple isolation features at once to
housekeeping interfaces, which soon won't be possible anymore as each
isolation features will have their own cpumask.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Phil Auld <pauld@redhat.com>
Link: https://lore.kernel.org/r/20220207155910.527133-5-frederic@kernel.org
As arm64 is about to introduce MTE-specific phdrs in the core dump, add
a common CONFIG_ARCH_BINFMT_ELF_EXTRA_PHDRS option currently selectable
by UML_X86 and IA64.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Link: https://lore.kernel.org/r/20220131165456.2160675-2-catalin.marinas@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
* Read HW interrupt pending state from the HW
x86:
* Don't truncate the performance event mask on AMD
* Fix Xen runstate updates to be atomic when preempting vCPU
* Fix for AMD AVIC interrupt injection race
* Several other AMD fixes
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull kvm fixes from Paolo Bonzini:
"ARM:
- Read HW interrupt pending state from the HW
x86:
- Don't truncate the performance event mask on AMD
- Fix Xen runstate updates to be atomic when preempting vCPU
- Fix for AMD AVIC interrupt injection race
- Several other AMD fixes"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: x86/pmu: Use AMD64_RAW_EVENT_MASK for PERF_TYPE_RAW
KVM: x86/pmu: Don't truncate the PerfEvtSeln MSR when creating a perf event
KVM: SVM: fix race between interrupt delivery and AVIC inhibition
KVM: SVM: set IRR in svm_deliver_interrupt
KVM: SVM: extract avic_ring_doorbell
selftests: kvm: Remove absent target file
KVM: arm64: vgic: Read HW interrupt pending state from the HW
KVM: x86/xen: Fix runstate updates to be atomic when preempting vCPU
KVM: x86: SVM: move avic definitions from AMD's spec to svm.h
KVM: x86: lapic: don't touch irr_pending in kvm_apic_update_apicv when inhibiting it
KVM: x86: nSVM: deal with L1 hypervisor that intercepts interrupts but lets L2 control them
KVM: x86: nSVM: expose clean bit support to the guest
KVM: x86: nSVM/nVMX: set nested_run_pending on VM entry which is a result of RSM
KVM: x86: nSVM: mark vmcb01 as dirty when restoring SMM saved state
KVM: x86: nSVM: fix potential NULL derefernce on nested migration
KVM: x86: SVM: don't passthrough SMAP/SMEP/PKE bits in !NPT && !gCR0.PG case
Revert "svm: Add warning message for AVIC IPI invalid target"
As of Intel SDM (https://www.intel.com/sdm) version 076, there is a new
Intel PT feature called TNT-Disable which is enabled config bit 55.
TNT-Disable disables Taken-Not-Taken packets to reduce the tracing
overhead, but with the result that exact control flow information is
lost.
Add a capability and config bit for TNT-Disable.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20220126104815.2807416-3-adrian.hunter@intel.com
As of Intel SDM (https://www.intel.com/sdm) version 076, there is a new
Intel PT feature called Event Trace which is enabled config bit 31.
Event Trace exposes details about asynchronous events such as interrupts
and VM-Entry/Exit.
Add a capability and config bit for Event Trace.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20220126104815.2807416-2-adrian.hunter@intel.com
The ENQCMD feature can only be used if CONFIG_INTEL_IOMMU_SVM is set.
Add X86_FEATURE_ENQCMD to the disabled features mask as appropriate so
that cpu_feature_enabled() can be used to check the feature.
[ bp: Massage commit message. ]
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220207230254.3342514-10-fenghua.yu@intel.com
All tasks start with PASID state disabled. This means that the first
time they execute an ENQCMD instruction they will take a #GP fault.
Modify the #GP fault handler to check if the "mm" for the task has
already been allocated a PASID. If so, try to fix the #GP fault by
loading the IA32_PASID MSR.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220207230254.3342514-9-fenghua.yu@intel.com
The kernel must allocate a Process Address Space ID (PASID) on behalf of
each process which will use ENQCMD and program it into the new MSR to
communicate the process identity to platform hardware. ENQCMD uses the
PASID stored in this MSR to tag requests from this process.
The PASID state must be cleared on fork() since fork creates a
new address space.
For clone(), it would be functionally OK to copy the PASID. However,
clearing it is _also_ functionally OK since any PASID use will trigger
the #GP handler to populate the MSR.
Copying the PASID state has two main downsides:
* It requires differentiating fork() and clone() in the code,
both in the FPU code and keeping tsk->pasid_activated consistent.
* It guarantees that the PASID is out of its init state, which
incurs small but non-zero cost on every XSAVE/XRSTOR.
The main downside of clearing the PASID at fpstate copy is the future,
one-time #GP for the thread.
Use the simplest approach: clear the PASID state both on clone() and
fork(). Rely on the #GP handler for MSR population in children.
Also, just clear the PASID bit from xfeatures if XSAVE is supported.
This will have no effect on systems that do not have PASID support. It
is virtually zero overhead because 'dst_fpu' was just written and
the whole thing is cache hot.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220207230254.3342514-7-fenghua.yu@intel.com
Use "avic" instead of "svm" for SVM's all of APICv hooks and make a few
additional funciton name tweaks so that the AVIC functions conform to
their associated kvm_x86_ops hooks.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220128005208.4008533-19-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
AMD's event select is 3 nybbles, with the high nybble in bits 35:32 of
a PerfEvtSeln MSR. Don't mask off the high nybble when configuring a
RAW perf event.
Fixes: ca724305a2 ("KVM: x86/vPMU: Implement AMD vPMU code for KVM")
Signed-off-by: Jim Mattson <jmattson@google.com>
Message-Id: <20220203014813.2130559-2-jmattson@google.com>
Reviewed-by: David Dunn <daviddunn@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
AMD's event select is 3 nybbles, with the high nybble in bits 35:32 of
a PerfEvtSeln MSR. Don't drop the high nybble when setting up the
config field of a perf_event_attr structure for a call to
perf_event_create_kernel_counter().
Fixes: ca724305a2 ("KVM: x86/vPMU: Implement AMD vPMU code for KVM")
Reported-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Jim Mattson <jmattson@google.com>
Message-Id: <20220203014813.2130559-1-jmattson@google.com>
Reviewed-by: David Dunn <daviddunn@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Backmerge tag 'v5.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux into drm-next
Daniel asked for this for some intel deps, so let's do it now.
Signed-off-by: Dave Airlie <airlied@redhat.com>
As done for memcpy(), also update memmove() to use the same tightened
compile-time checks under CONFIG_FORTIFY_SOURCE.
Signed-off-by: Kees Cook <keescook@chromium.org>
Explicitly zero select fields in the emulator's decode cache instead of
zeroing the fields via a gross memset() that spans six fields. gcc and
clang are both clever enough to batch the first five fields into a single
quadword MOV, i.e. memset() and individually zeroing generate identical
code.
Removing the wart also prepares KVM for FORTIFY_SOURCE performing
compile-time and run-time field bounds checking for memset().
No functional change intended.
Reported-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/lkml/YR0jIEzEcUom/7rd@google.com
Signed-off-by: Kees Cook <keescook@chromium.org>
The arch helpers do not have explicit KASAN instrumentation. Use them in
noinstr code.
Inline a couple more functions with single call sites, while at it:
mce_severity_amd_smca() has a single call-site which is noinstr so force
the inlining and fix:
vmlinux.o: warning: objtool: mce_severity_amd.constprop.0()+0xca: call to \
mce_severity_amd_smca() leaves .noinstr.text section
Always inline mca_msr_reg():
text data bss dec hex filename
16065240 128031326 36405368 180501934 ac23dae vmlinux.before
16065240 128031294 36405368 180501902 ac23d8e vmlinux.after
and mce_no_way_out() as the latter one is used only once, to fix:
vmlinux.o: warning: objtool: mce_read_aux()+0x53: call to mca_msr_reg() leaves .noinstr.text section
vmlinux.o: warning: objtool: do_machine_check()+0xc9: call to mce_no_way_out() leaves .noinstr.text section
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Marco Elver <elver@google.com>
Link: https://lore.kernel.org/r/20220204083015.17317-4-bp@alien8.de
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Merge tag 'objtool_urgent_for_v5.17_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool fix from Borislav Petkov:
"Fix a case where objtool would mistakenly warn about instructions
being unreachable"
* tag 'objtool_urgent_for_v5.17_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/bug: Merge annotate_reachable() into _BUG_FLAGS() asm
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Merge tag 'x86_urgent_for_v5.17_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fix from Borislav Petkov:
"Prevent softlockups when tearing down large SGX enclaves"
* tag 'x86_urgent_for_v5.17_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/sgx: Silence softlockup detection when releasing large enclaves
Instrumentation glue like KASAN causes the following warning:
vmlinux.o: warning: objtool: mce_gather_info()+0x5f: call to v8086_mode.constprop.0() leaves .noinstr.text section
due to gcc creating a function call for that oneliner. Force-inline it
and even save some vmlinux bytes (.config is close to an allmodconfig):
text data bss dec hex filename
209431677 208257651 34411048 452100376 1af28118 vmlinux.before
209431519 208257615 34411048 452100182 1af28056 vmlinux.after
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Marco Elver <elver@google.com>
Link: https://lore.kernel.org/r/20220204083015.17317-3-bp@alien8.de
Add a x86-specific cpumask_clear_cpu() helper which will be used in
places where the explicit KASAN-instrumentation in the *_bit() helpers
is unwanted.
Also, always inline two more cpumask generic helpers.
allyesconfig:
text data bss dec hex filename
190553143 159425889 32076404 382055436 16c5b40c vmlinux.before
190551812 159424945 32076404 382053161 16c5ab29 vmlinux.after
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Marco Elver <elver@google.com>
Link: https://lore.kernel.org/r/20220204083015.17317-2-bp@alien8.de
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Merge tag 'for-linus-5.17a-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
Pull xen fixes from Juergen Gross:
- Two small cleanups
- Another fix for addressing the EFI framebuffer above 4GB when running
as Xen dom0
- A patch to let Xen guests use reserved bits in MSI- and IO-APIC-
registers for extended APIC-IDs the same way KVM guests are doing it
already
* tag 'for-linus-5.17a-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
xen/pci: Make use of the helper macro LIST_HEAD()
xen/x2apic: Fix inconsistent indenting
xen/x86: detect support for extended destination ID
xen/x86: obtain full video frame buffer address for Dom0 also under EFI
This function was previously part of __startup_64() which is marked
__head, and is currently only called from there. Mark it __head too.
Signed-off-by: Marco Bonelli <marco@mebeim.net>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220211162350.11780-1-marco@mebeim.net
If svm_deliver_avic_intr is called just after the target vcpu's AVIC got
inhibited, it might read a stale value of vcpu->arch.apicv_active
which can lead to the target vCPU not noticing the interrupt.
To fix this use load-acquire/store-release so that, if the target vCPU
is IN_GUEST_MODE, we're guaranteed to see a previous disabling of the
AVIC. If AVIC has been disabled in the meanwhile, proceed with the
KVM_REQ_EVENT-based delivery.
Incomplete IPI vmexit has the same races as svm_deliver_avic_intr, and
in fact it can be handled in exactly the same way; the only difference
lies in who has set IRR, whether svm_deliver_interrupt or the processor.
Therefore, svm_complete_interrupt_delivery can be used to fix incomplete
IPI vmexits as well.
Co-developed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
SVM has to set IRR for both the AVIC and the software-LAPIC case,
so pull it up to the common function that handles both configurations.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The check on the current CPU adds an extra level of indentation to
svm_deliver_avic_intr and conflates documentation on what happens
if the vCPU exits (of interest to svm_deliver_avic_intr) and migrates
(only of interest to avic_ring_doorbell, which calls get/put_cpu()).
Extract the wrmsr to a separate function and rewrite the
comment in svm_deliver_avic_intr().
Co-developed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Modern compilers are perfectly capable of extracting parallelism from
the XOR routines, provided that the prototypes reflect the nature of the
input accurately, in particular, the fact that the input vectors are
expected not to overlap. This is not documented explicitly, but is
implied by the interchangeability of the various C routines, some of
which use temporary variables while others don't: this means that these
routines only behave identically for non-overlapping inputs.
So let's decorate these input vectors with the __restrict modifier,
which informs the compiler that there is no overlap. While at it, make
the input-only vectors pointer-to-const as well.
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/563
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Vijay reported that the "unclobbered_vdso_oversubscribed" selftest
triggers the softlockup detector.
Actual SGX systems have 128GB of enclave memory or more. The
"unclobbered_vdso_oversubscribed" selftest creates one enclave which
consumes all of the enclave memory on the system. Tearing down such a
large enclave takes around a minute, most of it in the loop where
the EREMOVE instruction is applied to each individual 4k enclave page.
Spending one minute in a loop triggers the softlockup detector.
Add a cond_resched() to give other tasks a chance to run and placate
the softlockup detector.
Cc: stable@vger.kernel.org
Fixes: 1728ab54b4 ("x86/sgx: Add a page reclaimer")
Reported-by: Vijay Dhanraj <vijay.dhanraj@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko@kernel.org> (kselftest as sanity check)
Link: https://lkml.kernel.org/r/ced01cac1e75f900251b0a4ae1150aa8ebd295ec.1644345232.git.reinette.chatre@intel.com
There is a local that contains a pointer to vcpu_vmx already. Just use
that instead to get at the structure directly instead of doing pointer
arithmetic.
No functional change intended.
Signed-off-by: Oliver Upton <oupton@google.com>
Message-Id: <20220204204705.3538240-8-oupton@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Similar to nVMX commit 502d2bf5f2 ("KVM: nVMX: Implement Enlightened MSR
Bitmap feature"), add support for the feature for nSVM (Hyper-V on KVM).
Notable differences from nVMX implementation:
- As the feature uses SW reserved fields in VMCB control, KVM needs to
make sure it's dealing with a Hyper-V guest (kvm_hv_hypercall_enabled()).
- 'msrpm_base_pa' needs to be always be overwritten in
nested_svm_vmrun_msrpm(), even when the update is skipped. As an
optimization, nested_vmcb02_prepare_control() copies it from VMCB01
so when MSR-Bitmap feature for L2 is disabled nothing needs to be done.
- 'struct vmcb_ctrl_area_cached' needs to be extended with clean
fields/sw reserved data and __nested_copy_vmcb_control_to_cache() needs to
copy it so nested_svm_vmrun_msrpm() can use it later.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220202095100.129834-5-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
In preparation to implementing Enlightened MSR-Bitmap feature for Hyper-V
on KVM, split off the required definitions into common 'svm/hyperv.h'
header.
No functional change intended.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220202095100.129834-4-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
In preparation for using kvm_hv_hypercall_enabled() from SVM code, make
it static inline to avoid the need to export it. The function is a
simple check with only two call sites currently.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220202095100.129834-3-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Similar to nVMX commit ed2a4800ae ("KVM: nVMX: Track whether changes in
L0 require MSR bitmap for L2 to be rebuilt"), introduce a flag to keep
track of whether MSR bitmap for L2 needs to be rebuilt due to changes in
MSR bitmap for L1 or switching to a different L2.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220202095100.129834-2-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add a tracepoint that records whenever KVM eagerly splits a huge page
and the error status of the split to indicate if it succeeded or failed
and why.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-18-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When using KVM_DIRTY_LOG_INITIALLY_SET, huge pages are not
write-protected when dirty logging is enabled on the memslot. Instead
they are write-protected once userspace invokes KVM_CLEAR_DIRTY_LOG for
the first time and only for the specific sub-region being cleared.
Enhance KVM_CLEAR_DIRTY_LOG to also try to split huge pages prior to
write-protecting to avoid causing write-protection faults on vCPU
threads. This also allows userspace to smear the cost of huge page
splitting across multiple ioctls, rather than splitting the entire
memslot as is the case when initially-all-set is not used.
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-17-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When dirty logging is enabled without initially-all-set, try to split
all huge pages in the memslot down to 4KB pages so that vCPUs do not
have to take expensive write-protection faults to split huge pages.
Eager page splitting is best-effort only. This commit only adds the
support for the TDP MMU, and even there splitting may fail due to out
of memory conditions. Failures to split a huge page is fine from a
correctness standpoint because KVM will always follow up splitting by
write-protecting any remaining huge pages.
Eager page splitting moves the cost of splitting huge pages off of the
vCPU threads and onto the thread enabling dirty logging on the memslot.
This is useful because:
1. Splitting on the vCPU thread interrupts vCPUs execution and is
disruptive to customers whereas splitting on VM ioctl threads can
run in parallel with vCPU execution.
2. Splitting all huge pages at once is more efficient because it does
not require performing VM-exit handling or walking the page table for
every 4KiB page in the memslot, and greatly reduces the amount of
contention on the mmu_lock.
For example, when running dirty_log_perf_test with 96 virtual CPUs, 1GiB
per vCPU, and 1GiB HugeTLB memory, the time it takes vCPUs to write to
all of their memory after dirty logging is enabled decreased by 95% from
2.94s to 0.14s.
Eager Page Splitting is over 100x more efficient than the current
implementation of splitting on fault under the read lock. For example,
taking the same workload as above, Eager Page Splitting reduced the CPU
required to split all huge pages from ~270 CPU-seconds ((2.94s - 0.14s)
* 96 vCPU threads) to only 1.55 CPU-seconds.
Eager page splitting does increase the amount of time it takes to enable
dirty logging since it has split all huge pages. For example, the time
it took to enable dirty logging in the 96GiB region of the
aforementioned test increased from 0.001s to 1.55s.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-16-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Separate the allocation of shadow pages from their initialization. This
is in preparation for splitting huge pages outside of the vCPU fault
context, which requires a different allocation mechanism.
No functional changed intended.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-15-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Derive the page role from the parent shadow page, since the only thing
that changes is the level. This is in preparation for splitting huge
pages during VM-ioctls which do not have access to the vCPU MMU context.
No functional change intended.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-14-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The vCPU's mmu_role already has the correct values for direct,
has_4_byte_gpte, access, and ad_disabled. Remove the code that was
redundantly overwriting these fields with the same values.
No functional change intended.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-13-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Instead of passing a pointer to the root page table and the root level
separately, pass in a pointer to the root kvm_mmu_page struct. This
reduces the number of arguments by 1, cutting down on line lengths.
No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-12-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
restore_acc_track_spte() is pure SPTE bit manipulation, making it a good
fit for spte.h. And now that the WARN_ON_ONCE() calls have been removed,
there isn't any good reason to not inline it.
This move also prepares for a follow-up commit that will need to call
restore_acc_track_spte() from spte.c
No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-11-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The new_spte local variable is unnecessary. Deleting it can save a line
of code and simplify the remaining lines a bit.
No functional change intended.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-10-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The warnings in restore_acc_track_spte() can be removed because the only
caller checks is_access_track_spte(), and is_access_track_spte() checks
!spte_ad_enabled(). In other words, the warning can never be triggered.
No functional change intended.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-9-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Consolidate the logic to atomically replace an SPTE with an SPTE that
points to a new page table into a single helper function. This will be
used in a follow-up commit to split huge pages, which involves replacing
each huge page SPTE with an SPTE that points to a page table.
Opportunistically drop the call to trace_kvm_mmu_get_page() in
kvm_tdp_mmu_map() since it is redundant with the identical tracepoint in
tdp_mmu_alloc_sp().
No functional change intended.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-8-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
First remove tdp_mmu_ from the name since it is redundant given that it
is a static function in tdp_mmu.c. There is a pattern of using tdp_mmu_
as a prefix in the names of static TDP MMU functions, but all of the
other handle_*() variants do not include such a prefix. So drop it
entirely.
Then change "page" to "pt" to convey that this is operating on a page
table rather than an struct page. Purposely use "pt" instead of "sp"
since this function takes the raw RCU-protected page table pointer as an
argument rather than a pointer to the struct kvm_mmu_page.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-7-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Rename 3 functions in tdp_mmu.c that handle shadow pages:
alloc_tdp_mmu_page() -> tdp_mmu_alloc_sp()
tdp_mmu_link_page() -> tdp_mmu_link_sp()
tdp_mmu_unlink_page() -> tdp_mmu_unlink_sp()
These changed make tdp_mmu a consistent prefix before the verb in the
function name, and make it more clear that these functions deal with
kvm_mmu_page structs rather than struct pages.
One could argue that "shadow page" is the wrong term for a page table in
the TDP MMU since it never actually shadows a guest page table.
However, "shadow page" (or "sp" for short) has evolved to become the
standard term in KVM when referring to a kvm_mmu_page struct, and its
associated page table and other metadata, regardless of whether the page
table shadows a guest page table. So this commit just makes the TDP MMU
more consistent with the rest of KVM.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-6-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
tdp_mmu_set_spte_atomic() and tdp_mmu_zap_spte_atomic() return a bool
with true indicating the SPTE modification was successful and false
indicating failure. Change these functions to return an int instead
since that is the common practice.
Opportunistically fix up the kernel-doc style for the Return section
above tdp_mmu_set_spte_atomic().
No functional change intended.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-5-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Consolidate a bunch of code that was manually re-reading the spte if the
cmpxchg failed. There is no extra cost of doing this because we already
have the spte value as a result of the cmpxchg (and in fact this
eliminates re-reading the spte), and none of the call sites depend on
iter->old_spte retaining the stale spte value.
Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-4-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The function formerly known as rmap_write_protect() has been renamed to
kvm_vcpu_write_protect_gfn(), so we can get rid of the double
underscores in front of __rmap_write_protect().
No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-3-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
rmap_write_protect() is a poor name because it also write-protects SPTEs
in the TDP MMU, not just SPTEs in the rmap. It is also confusing that
rmap_write_protect() is not a simple wrapper around
__rmap_write_protect(), since that is the common pattern for functions
with double-underscore names.
Rename rmap_write_protect() to kvm_vcpu_write_protect_gfn() to convey
that KVM is write-protecting a specific gfn in the context of a vCPU.
No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-2-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add checks for the three fields in Hyper-V's hypercall params that must
be zero. Per the TLFS, HV_STATUS_INVALID_HYPERCALL_INPUT is returned if
"A reserved bit in the specified hypercall input value is non-zero."
Note, some versions of the TLFS have an off-by-one bug for the last
reserved field, and define it as being bits 64:60. See
https://github.com/MicrosoftDocs/Virtualization-Documentation/pull/1682.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20211207220926.718794-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reject Hyper-V hypercalls if the guest specifies a non-zero variable size
header (var_cnt in KVM) for a hypercall that has a fixed header size.
Per the TLFS:
It is illegal to specify a non-zero variable header size for a
hypercall that is not explicitly documented as accepting variable sized
input headers. In such a case the hypercall will result in a return
code of HV_STATUS_INVALID_HYPERCALL_INPUT.
Note, at least some of the various DEBUG commands likely aren't allowed
to use variable size headers, but the TLFS documentation doesn't clearly
state what is/isn't allowed. Omit them for now to avoid unnecessary
breakage.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20211207220926.718794-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Move the vp_bitmap "allocation" that's needed to handle mismatched vp_index
values down into sparse_set_to_vcpu_mask() and drop __always_inline from
said helper. The need for an intermediate vp_bitmap is a detail that's
specific to the sparse translation with mismatched VP<=>vCPU indexes and
does not need to be exposed to the caller.
Regarding the __always_inline, prior to commit f21dd49450 ("KVM: x86:
hyperv: optimize sparse VP set processing") the helper, then named
hv_vcpu_in_sparse_set(), was a tiny bit of code that effectively boiled
down to a handful of bit ops. The __always_inline was understandable, if
not justifiable. Since the aforementioned change, sparse_set_to_vcpu_mask()
is a chunky 350-450+ bytes of code without KASAN=y, and balloons to 1100+
with KASAN=y. In other words, it has no business being forcefully inlined.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20211207220926.718794-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When handling "sparse" VP_SET requests, don't read sparse banks that
can't possibly contain a legal VP index instead of ignoring such banks
later on in sparse_set_to_vcpu_mask(). This allows KVM to cap the size
of its sparse_banks arrays for VP_SET at KVM_HV_MAX_SPARSE_VCPU_SET_BITS.
Add a compile time assert that KVM_HV_MAX_SPARSE_VCPU_SET_BITS<=64, i.e.
that KVM_MAX_VCPUS<=4096, as the TLFS allows for at most 64 sparse banks,
and KVM will need to do _something_ to play nice with Hyper-V.
Reducing the size of sparse_banks fudges around a compilation warning
(that becomes error with KVM_WERROR=y) when CONFIG_KASAN_STACK=y, which
is selected (and can't be unselected) by CONFIG_KASAN=y when using gcc
(clang/LLVM is a stack hog in some cases so it's opt-in for clang).
KASAN_STACK adds a redzone around every stack variable, which pushes the
Hyper-V functions over the default limit of 1024.
Ideally, KVM would flat out reject such impossibilities, but the TLFS
explicitly allows providing empty banks, even if a bank can't possibly
contain a valid VP index due to its position exceeding KVM's max.
Furthermore, for a bit 1 in ValidBankMask, it is valid state for the
corresponding element in BanksContents can be all 0s, meaning no
processors are specified in this bank.
Arguably KVM should reject and not ignore the "extra" banks, but that can
be done independently and without bloating sparse_banks, e.g. by reading
each "extra" 8-byte chunk individually.
Reported-by: Ajay Garg <ajaygargnsit@gmail.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20211207220926.718794-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add a helper, kvm_get_sparse_vp_set(), to handle sanity checks related to
the VARHEAD field and reading the sparse banks of a VP_SET. A future
commit to reduce the memory footprint of sparse_banks will introduce more
common code to the sparse bank retrieval.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20211207220926.718794-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Refactor the "extended" path of kvm_hv_flush_tlb() to reduce the nesting
depth for the non-fast sparse path, and to make the code more similar to
the extended path in kvm_hv_send_ipi().
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20211207220926.718794-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Get the number of sparse banks from the VARHEAD field, which the guest is
required to provide as "The size of a variable header, in QWORDS.", where
the variable header is:
Variable Header Bytes = {Total Header Bytes - sizeof(Fixed Header)}
rounded up to nearest multiple of 8
Variable HeaderSize = Variable Header Bytes / 8
In other words, the VARHEAD should match the number of sparse banks.
Keep the manual count as a sanity check, but otherwise rely on the field
so as to more closely align with the logic defined in the TLFS and to
allow for future cleanups.
Tweak the tracepoint output to use "rep_cnt" instead of simply "cnt" now
that there is also "var_cnt".
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20211207220926.718794-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Consolidate the large comment above DEFAULT_SPTE_HOST_WRITABLE with the
large comment above is_writable_pte() into one comment. This comment
explains the different reasons why an SPTE may be non-writable and KVM
keeps track of that with the {Host,MMU}-writable bits.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220125230723.1701061-1-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Both "writeable" and "writable" are valid, but we should be consistent
about which we use. DEFAULT_SPTE_MMU_WRITEABLE was the odd one out in
the SPTE code, so rename it to DEFAULT_SPTE_MMU_WRITABLE.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220125230713.1700406-1-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Move is_writable_pte() close to the other functions that check
writability information about SPTEs. While here opportunistically
replace the open-coded bit arithmetic in
check_spte_writable_invariants() with a call to is_writable_pte().
No functional change intended.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220125230518.1697048-4-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Check SPTE writable invariants when setting SPTEs rather than in
spte_can_locklessly_be_made_writable(). By the time KVM checks
spte_can_locklessly_be_made_writable(), the SPTE has long been since
corrupted.
Note that these invariants only apply to shadow-present leaf SPTEs (i.e.
not to MMIO SPTEs, non-leaf SPTEs, etc.). Add a comment explaining the
restriction and only instrument the code paths that set shadow-present
leaf SPTEs.
To account for access tracking, also check the SPTE writable invariants
when marking an SPTE as an access track SPTE. This also lets us remove
a redundant WARN from mark_spte_for_access_track().
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220125230518.1697048-3-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Move the WARNs in spte_can_locklessly_be_made_writable() to a separate
helper function. This is in preparation for moving these checks to the
places where SPTEs are set.
Opportunistically add warning error messages that include the SPTE to
make future debugging of these warnings easier.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220125230518.1697048-2-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
As commit 0c5f81dad4 ("KVM: LAPIC: Inject timer interrupt via posted
interrupt") mentioned that the host admin should well tune the guest
setup, so that vCPUs are placed on isolated pCPUs, and with several pCPUs
surplus for *busy* housekeeping. In this setup, it is preferrable to
disable mwait/hlt/pause vmexits to keep the vCPUs in non-root mode.
However, if only some guests isolated and others not, they would not
have any benefit from posted timer interrupts, and at the same time lose
VMX preemption timer fast paths because kvm_can_post_timer_interrupt()
returns true and therefore forces kvm_can_use_hv_timer() to false.
By guaranteeing that posted-interrupt timer is only used if MWAIT or
HLT are done without vmexit, KVM can make a better choice and use the
VMX preemption timer and the corresponding fast paths.
Reported-by: Aili Yao <yaoaili@kingsoft.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Cc: Aili Yao <yaoaili@kingsoft.com>
Cc: Sean Christopherson <seanjc@google.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1643112538-36743-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
