VPID for the nested vcpu is allocated at vmx_create_vcpu whenever nested
vmx is turned on with the module parameter.
However, it's only freed if the L1 guest has executed VMXON which is not
a given.
As a result, on a system with nested==on every creation+deletion of an
L1 vcpu without running an L2 guest results in leaking one vpid. Since
the total number of vpids is limited to 64k, they can eventually get
exhausted, preventing L2 from starting.
Delay allocation of the L2 vpid until VMXON emulation, thus matching its
freeing.
Fixes: 5c614b3583
Cc: stable@vger.kernel.org
Signed-off-by: Roman Kagan <rkagan@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Do not expose the address of vmx->nested.current_vmptr to
kvm_write_guest_virt_system() as the resulting __copy_to_user()
call will trigger a WARN when CONFIG_HARDENED_USERCOPY is
enabled.
Opportunistically clean up variable names in handle_vmptrst()
to improve readability, e.g. vmcs_gva is misleading as the
memory operand of VMPTRST is plain memory, not a VMCS.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Tested-by: Peter Shier <pshier@google.com>
Reviewed-by: Peter Shier <pshier@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull kvm fixes from Paolo Bonzini:
"Miscellaneous bugfixes, plus a small patchlet related to Spectre v2"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
kvmclock: fix TSC calibration for nested guests
KVM: VMX: Mark VMXArea with revision_id of physical CPU even when eVMCS enabled
KVM: irqfd: fix race between EPOLLHUP and irq_bypass_register_consumer
KVM/Eventfd: Avoid crash when assign and deassign specific eventfd in parallel.
x86/kvmclock: set pvti_cpu0_va after enabling kvmclock
x86/kvm/Kconfig: Ensure CRYPTO_DEV_CCP_DD state at minimum matches KVM_AMD
kvm: nVMX: Restore exit qual for VM-entry failure due to MSR loading
x86/kvm/vmx: don't read current->thread.{fs,gs}base of legacy tasks
KVM: VMX: support MSR_IA32_ARCH_CAPABILITIES as a feature MSR
When eVMCS is enabled, all VMCS allocated to be used by KVM are marked
with revision_id of KVM_EVMCS_VERSION instead of revision_id reported
by MSR_IA32_VMX_BASIC.
However, even though not explictly documented by TLFS, VMXArea passed
as VMXON argument should still be marked with revision_id reported by
physical CPU.
This issue was found by the following setup:
* L0 = KVM which expose eVMCS to it's L1 guest.
* L1 = KVM which consume eVMCS reported by L0.
This setup caused the following to occur:
1) L1 execute hardware_enable().
2) hardware_enable() calls kvm_cpu_vmxon() to execute VMXON.
3) L0 intercept L1 VMXON and execute handle_vmon() which notes
vmxarea->revision_id != VMCS12_REVISION and therefore fails with
nested_vmx_failInvalid() which sets RFLAGS.CF.
4) L1 kvm_cpu_vmxon() don't check RFLAGS.CF for failure and therefore
hardware_enable() continues as usual.
5) L1 hardware_enable() then calls ept_sync_global() which executes
INVEPT.
6) L0 intercept INVEPT and execute handle_invept() which notes
!vmx->nested.vmxon and thus raise a #UD to L1.
7) Raised #UD caused L1 to panic.
Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Cc: stable@vger.kernel.org
Fixes: 773e8a0425
Signed-off-by: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This exit qualification was inadvertently dropped when the two
VM-entry failure blocks were coalesced.
Fixes: e79f245dde ("X86/KVM: Properly update 'tsc_offset' to represent the running guest")
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When we switched from doing rdmsr() to reading FS/GS base values from
current->thread we completely forgot about legacy 32-bit userspaces which
we still support in KVM (why?). task->thread.{fsbase,gsbase} are only
synced for 64-bit processes, calling save_fsgs_for_kvm() and using
its result from current is illegal for legacy processes.
There's no ARCH_SET_FS/GS prctls for legacy applications. Base MSRs are,
however, not always equal to zero. Intel's manual says (3.4.4 Segment
Loading Instructions in IA-32e Mode):
"In order to set up compatibility mode for an application, segment-load
instructions (MOV to Sreg, POP Sreg) work normally in 64-bit mode. An
entry is read from the system descriptor table (GDT or LDT) and is loaded
in the hidden portion of the segment register.
...
The hidden descriptor register fields for FS.base and GS.base are
physically mapped to MSRs in order to load all address bits supported by
a 64-bit implementation.
"
The issue was found by strace test suite where 32-bit ioctl_kvm_run test
started segfaulting.
Reported-by: Dmitry V. Levin <ldv@altlinux.org>
Bisected-by: Masatake YAMATO <yamato@redhat.com>
Fixes: 42b933b597 ("x86/kvm/vmx: read MSR_{FS,KERNEL_GS}_BASE from current->thread")
Cc: stable@vger.kernel.org
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This patch extends the checks done prior to a nested VM entry.
Specifically, it extends the check_vmentry_prereqs function with checks
for fields relevant to the VM-entry event injection information, as
described in the Intel SDM, volume 3.
This patch is motivated by a syzkaller bug, where a bad VM-entry
interruption information field is generated in the VMCS02, which causes
the nested VM launch to fail. Then, KVM fails to resume L1.
While KVM should be improved to correctly resume L1 execution after a
failed nested launch, this change is justified because the existing code
to resume L1 is flaky/ad-hoc and the test coverage for resuming L1 is
sparse.
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Marc Orr <marcorr@google.com>
[Removed comment whose parts were describing previous revisions and the
rest was obvious from function/variable naming. - Radim]
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Arnd had sent this patch to the KVM mailing list, but it slipped through
the cracks of maintainers hand-off, and therefore wasn't included in
the pull request.
The same issue had been fixed by Linus in commit dbee3d0 ("KVM: x86:
VMX: fix build without hyper-v", 2018-06-12) as a self-described
"quick-and-hacky build fix". However, checking the compile-time
configuration symbol with IS_ENABLED is cleaner and it is enough to
avoid the link error, so switch to Arnd's solution.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
[Rewritten commit message. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Commit ceef7d10df ("KVM: x86: VMX: hyper-v: Enlightened MSR-Bitmap
support") broke the build with Hyper-V disabled, because it accesses
ms_hyperv.nested_features without checking if that exists.
This is the quick-and-hacky build fix.
I suspect the proper fix is to replace the
static_branch_unlikely(&enable_evmcs)
tests with an inline helper function that also checks that CONFIG_HYPERV
is enabled, since without that, enable_evmcs makes no sense.
But I want a working build environment first and foremost, and I'm upset
this slipped through in the first place. My primary build tests missed
it because I tend to build with everything enabled, but it should have
been caught in the kvm tree.
Fixes: ceef7d10df ("KVM: x86: VMX: hyper-v: Enlightened MSR-Bitmap support")
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ARM: lazy context-switching of FPSIMD registers on arm64, "split"
regions for vGIC redistributor
* s390: cleanups for nested, clock handling, crypto, storage keys and
control register bits
* x86: many bugfixes, implement more Hyper-V super powers,
implement lapic_timer_advance_ns even when the LAPIC timer
is emulated using the processor's VMX preemption timer. Two
security-related bugfixes at the top of the branch.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM updates from Paolo Bonzini:
"Small update for KVM:
ARM:
- lazy context-switching of FPSIMD registers on arm64
- "split" regions for vGIC redistributor
s390:
- cleanups for nested
- clock handling
- crypto
- storage keys
- control register bits
x86:
- many bugfixes
- implement more Hyper-V super powers
- implement lapic_timer_advance_ns even when the LAPIC timer is
emulated using the processor's VMX preemption timer.
- two security-related bugfixes at the top of the branch"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (79 commits)
kvm: fix typo in flag name
kvm: x86: use correct privilege level for sgdt/sidt/fxsave/fxrstor access
KVM: x86: pass kvm_vcpu to kvm_read_guest_virt and kvm_write_guest_virt_system
KVM: x86: introduce linear_{read,write}_system
kvm: nVMX: Enforce cpl=0 for VMX instructions
kvm: nVMX: Add support for "VMWRITE to any supported field"
kvm: nVMX: Restrict VMX capability MSR changes
KVM: VMX: Optimize tscdeadline timer latency
KVM: docs: nVMX: Remove known limitations as they do not exist now
KVM: docs: mmu: KVM support exposing SLAT to guests
kvm: no need to check return value of debugfs_create functions
kvm: Make VM ioctl do valloc for some archs
kvm: Change return type to vm_fault_t
KVM: docs: mmu: Fix link to NPT presentation from KVM Forum 2008
kvm: x86: Amend the KVM_GET_SUPPORTED_CPUID API documentation
KVM: x86: hyperv: declare KVM_CAP_HYPERV_TLBFLUSH capability
KVM: x86: hyperv: simplistic HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE}_EX implementation
KVM: x86: hyperv: simplistic HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE} implementation
KVM: introduce kvm_make_vcpus_request_mask() API
KVM: x86: hyperv: do rep check for each hypercall separately
...
Int the next patch the emulator's .read_std and .write_std callbacks will
grow another argument, which is not needed in kvm_read_guest_virt and
kvm_write_guest_virt_system's callers. Since we have to make separate
functions, let's give the currently existing names a nicer interface, too.
Fixes: 129a72a0d3 ("KVM: x86: Introduce segmented_write_std", 2017-01-12)
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
VMX instructions executed inside a L1 VM will always trigger a VM exit
even when executed with cpl 3. This means we must perform the
privilege check in software.
Fixes: 70f3aac964ae("kvm: nVMX: Remove superfluous VMX instruction fault checks")
Cc: stable@vger.kernel.org
Signed-off-by: Felix Wilhelm <fwilhelm@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add support for "VMWRITE to any supported field in the VMCS" and
enable this feature by default in L1's IA32_VMX_MISC MSR. If userspace
clears the VMX capability bit, the old behavior will be restored.
Note that this feature is a prerequisite for kvm in L1 to use VMCS
shadowing, once that feature is available.
Signed-off-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Disallow changes to the VMX capability MSRs while the vCPU is in VMX
operation. Although this does break the existing API, it helps to
avoid some potentially tricky situations for which there is no
architected behavior.
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
'Commit d0659d946b ("KVM: x86: add option to advance tscdeadline
hrtimer expiration")' advances the tscdeadline (the timer is emulated
by hrtimer) expiration in order that the latency which is incurred
by hypervisor (apic_timer_fn -> vmentry) can be avoided. This patch
adds the advance tscdeadline expiration support to which the tscdeadline
timer is emulated by VMX preemption timer to reduce the hypervisor
lantency (handle_preemption_timer -> vmentry). The guest can also
set an expiration that is very small (for example in Linux if an
hrtimer feeds a expiration in the past); in that case we set delta_tsc
to 0, leading to an immediately vmexit when delta_tsc is not bigger than
advance ns.
This patch can reduce ~63% latency (~4450 cycles to ~1660 cycles on
a haswell desktop) for kvm-unit-tests/tscdeadline_latency when testing
busy waits.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The kvm struct has been bloating. For example, it's tens of kilo-bytes
for x86, which turns out to be a large amount of memory to allocate
contiguously via kzalloc. Thus, this patch does the following:
1. Uses architecture-specific routines to allocate the kvm struct via
vzalloc for x86.
2. Switches arm to __KVM_HAVE_ARCH_VM_ALLOC so that it can use vzalloc
when has_vhe() is true.
Other architectures continue to default to kalloc, as they have a
dependency on kalloc or have a small-enough struct kvm.
Signed-off-by: Marc Orr <marcorr@google.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When vmcs12 uses VPID, all TLB entries populated by L2 are tagged with
vmx->nested.vpid02. Currently, INVVPID executed by L1 is emulated by L0
by using INVVPID single/global-context to flush all TLB entries
tagged with vmx->nested.vpid02 regardless of INVVPID type executed by
L1.
However, we can easily optimize the case of L1 INVVPID on an
individual-address. Just INVVPID given individual-address tagged with
vmx->nested.vpid02.
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Signed-off-by: Liran Alon <liran.alon@oracle.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
[Squashed with a preparatory patch that added the !operand.vpid line.]
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Since commit 5c614b3583 ("KVM: nVMX: nested VPID emulation"),
vmcs01 and vmcs02 don't share the same VPID. vmcs01 uses vmx->vpid
while vmcs02 uses vmx->nested.vpid02. This was done such that TLB
flush could be avoided when switching between L1 and L2.
However, the above mentioned commit only changed L2 VMEntry logic to
not flush TLB when switching from L1 to L2. It forgot to also remove
the TLB flush which is done when simulating a VMExit from L2 to L1.
To fix this issue, on VMExit from L2 to L1 we flush TLB only in case
vmcs01 enables VPID and vmcs01->vpid==vmcs02->vpid. This happens when
vmcs01 enables VPID and vmcs12 does not.
Fixes: 5c614b3583 ("KVM: nVMX: nested VPID emulation")
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Signed-off-by: Liran Alon <liran.alon@oracle.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Enforce the invariant that existing VMCS12 field offsets must not
change. Experience has shown that without strict enforcement, this
invariant will not be maintained.
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
[Changed the code to use BUILD_BUG_ON_MSG instead of better, but GCC 4.6
requiring _Static_assert. - Radim.]
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Changing the VMCS12 layout will break save/restore compatibility with
older kvm releases once the KVM_{GET,SET}_NESTED_STATE ioctls are
accepted upstream. Google has already been using these ioctls for some
time, and we implore the community not to disturb the existing layout.
Move the four most recently added fields to preserve the offsets of
the previously defined fields and reserve locations for the vmread and
vmwrite bitmaps, which will be used in the virtualization of VMCS
shadowing (to improve the performance of double-nesting).
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
[Kept the SDM order in vmcs_field_to_offset_table. - Radim]
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
When saving a vCPU's nested state, the vmcs02 is discarded. Only the
shadow vmcs12 is saved. The shadow vmcs12 contains all of the
information needed to reconstruct an equivalent vmcs02 on restore, but
we have to be able to deal with two contexts:
1. The nested state was saved immediately after an emulated VM-entry,
before the vmcs02 was ever launched.
2. The nested state was saved some time after the first successful
launch of the vmcs02.
Though it's an implementation detail rather than an architected bit,
vmx->nested_run_pending serves to distinguish between these two
cases. Hence, we save it as part of the vCPU's nested state. (Yes,
this is ugly.)
Even when restoring from a checkpoint, it may be necessary to build
the vmcs02 as if prepare_vmcs02 was called from nested_vmx_run. So,
the 'from_vmentry' argument should be dropped, and
vmx->nested_run_pending should be consulted instead. The nested state
restoration code then has to set vmx->nested_run_pending prior to
calling prepare_vmcs02. It's important that the restoration code set
vmx->nested_run_pending anyway, since the flag impacts things like
interrupt delivery as well.
Fixes: cf8b84f48a ("kvm: nVMX: Prepare for checkpointing L2 state")
Signed-off-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Merge speculative store buffer bypass fixes from Thomas Gleixner:
- rework of the SPEC_CTRL MSR management to accomodate the new fancy
SSBD (Speculative Store Bypass Disable) bit handling.
- the CPU bug and sysfs infrastructure for the exciting new Speculative
Store Bypass 'feature'.
- support for disabling SSB via LS_CFG MSR on AMD CPUs including
Hyperthread synchronization on ZEN.
- PRCTL support for dynamic runtime control of SSB
- SECCOMP integration to automatically disable SSB for sandboxed
processes with a filter flag for opt-out.
- KVM integration to allow guests fiddling with SSBD including the new
software MSR VIRT_SPEC_CTRL to handle the LS_CFG based oddities on
AMD.
- BPF protection against SSB
.. this is just the core and x86 side, other architecture support will
come separately.
* 'speck-v20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (49 commits)
bpf: Prevent memory disambiguation attack
x86/bugs: Rename SSBD_NO to SSB_NO
KVM: SVM: Implement VIRT_SPEC_CTRL support for SSBD
x86/speculation, KVM: Implement support for VIRT_SPEC_CTRL/LS_CFG
x86/bugs: Rework spec_ctrl base and mask logic
x86/bugs: Remove x86_spec_ctrl_set()
x86/bugs: Expose x86_spec_ctrl_base directly
x86/bugs: Unify x86_spec_ctrl_{set_guest,restore_host}
x86/speculation: Rework speculative_store_bypass_update()
x86/speculation: Add virtualized speculative store bypass disable support
x86/bugs, KVM: Extend speculation control for VIRT_SPEC_CTRL
x86/speculation: Handle HT correctly on AMD
x86/cpufeatures: Add FEATURE_ZEN
x86/cpufeatures: Disentangle SSBD enumeration
x86/cpufeatures: Disentangle MSR_SPEC_CTRL enumeration from IBRS
x86/speculation: Use synthetic bits for IBRS/IBPB/STIBP
KVM: SVM: Move spec control call after restore of GS
x86/cpu: Make alternative_msr_write work for 32-bit code
x86/bugs: Fix the parameters alignment and missing void
x86/bugs: Make cpu_show_common() static
...
Expose the new virtualized architectural mechanism, VIRT_SSBD, for using
speculative store bypass disable (SSBD) under SVM. This will allow guests
to use SSBD on hardware that uses non-architectural mechanisms for enabling
SSBD.
[ tglx: Folded the migration fixup from Paolo Bonzini ]
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
AMD is proposing a VIRT_SPEC_CTRL MSR to handle the Speculative Store
Bypass Disable via MSR_AMD64_LS_CFG so that guests do not have to care
about the bit position of the SSBD bit and thus facilitate migration.
Also, the sibling coordination on Family 17H CPUs can only be done on
the host.
Extend x86_spec_ctrl_set_guest() and x86_spec_ctrl_restore_host() with an
extra argument for the VIRT_SPEC_CTRL MSR.
Hand in 0 from VMX and in SVM add a new virt_spec_ctrl member to the CPU
data structure which is going to be used in later patches for the actual
implementation.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Intel and AMD have different CPUID bits hence for those use synthetic bits
which get set on the respective vendor's in init_speculation_control(). So
that debacles like what the commit message of
c65732e4f7 ("x86/cpu: Restore CPUID_8000_0008_EBX reload")
talks about don't happen anymore.
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-by: Jörg Otte <jrg.otte@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Link: https://lkml.kernel.org/r/20180504161815.GG9257@pd.tnic
It is only possible to share the APIC access page between L1 and L2 if
they also share the virtual-APIC page. If L2 has its own virtual-APIC
page, then MMIO accesses to L1's TPR from L2 will access L2's TPR
instead. Moreover, L1's local APIC has to be in xAPIC mode, which is
another condition that hasn't been checked.
Signed-off-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Previously, we toggled between SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE
and SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES, depending on whether or
not the EXTD bit was set in MSR_IA32_APICBASE. However, if the local
APIC is disabled, we should not set either of these APIC
virtualization control bits.
Signed-off-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Enlightened MSR-Bitmap is a natural extension of Enlightened VMCS:
Hyper-V Top Level Functional Specification states:
"The L1 hypervisor may collaborate with the L0 hypervisor to make MSR
accesses more efficient. It can enable enlightened MSR bitmaps by setting
the corresponding field in the enlightened VMCS to 1. When enabled, the L0
hypervisor does not monitor the MSR bitmaps for changes. Instead, the L1
hypervisor must invalidate the corresponding clean field after making
changes to one of the MSR bitmaps."
I reached out to Hyper-V team for additional details and I got the
following information:
"Current Hyper-V implementation works as following:
If the enlightened MSR bitmap is not enabled:
- All MSR accesses of L2 guests cause physical VM-Exits
If the enlightened MSR bitmap is enabled:
- Physical VM-Exits for L2 accesses to certain MSRs (currently FS_BASE,
GS_BASE and KERNEL_GS_BASE) are avoided, thus making these MSR accesses
faster."
I tested my series with a tight rdmsrl loop in L2, for KERNEL_GS_BASE the
results are:
Without Enlightened MSR-Bitmap: 1300 cycles/read
With Enlightened MSR-Bitmap: 120 cycles/read
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Tested-by: Lan Tianyu <Tianyu.Lan@microsoft.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Update SECONDARY_EXEC_DESC for UMIP emulation if and only UMIP
is actually being emulated. Skipping the VMCS update eliminates
unnecessary VMREAD/VMWRITE when UMIP is supported in hardware,
and on platforms that don't have SECONDARY_VM_EXEC_CONTROL. The
latter case resolves a bug where KVM would fill the kernel log
with warnings due to failed VMWRITEs on older platforms.
Fixes: 0367f205a3 ("KVM: vmx: add support for emulating UMIP")
Cc: stable@vger.kernel.org #4.16
Reported-by: Paolo Zeppegno <pzeppegno@gmail.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Suggested-by: Radim KrÄmář <rkrcmar@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Intel collateral will reference the SSB mitigation bit in IA32_SPEC_CTL[2]
as SSBD (Speculative Store Bypass Disable).
Hence changing it.
It is unclear yet what the MSR_IA32_ARCH_CAPABILITIES (0x10a) Bit(4) name
is going to be. Following the rename it would be SSBD_NO but that rolls out
to Speculative Store Bypass Disable No.
Also fixed the missing space in X86_FEATURE_AMD_SSBD.
[ tglx: Fixup x86_amd_rds_enable() and rds_tif_to_amd_ls_cfg() as well ]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Having everything in nospec-branch.h creates a hell of dependencies when
adding the prctl based switching mechanism. Move everything which is not
required in nospec-branch.h to spec-ctrl.h and fix up the includes in the
relevant files.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Expose the CPUID.7.EDX[31] bit to the guest, and also guard against various
combinations of SPEC_CTRL MSR values.
The handling of the MSR (to take into account the host value of SPEC_CTRL
Bit(2)) is taken care of in patch:
KVM/SVM/VMX/x86/spectre_v2: Support the combination of guest and host IBRS
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
A guest may modify the SPEC_CTRL MSR from the value used by the
kernel. Since the kernel doesn't use IBRS, this means a value of zero is
what is needed in the host.
But the 336996-Speculative-Execution-Side-Channel-Mitigations.pdf refers to
the other bits as reserved so the kernel should respect the boot time
SPEC_CTRL value and use that.
This allows to deal with future extensions to the SPEC_CTRL interface if
any at all.
Note: This uses wrmsrl() instead of native_wrmsl(). I does not make any
difference as paravirt will over-write the callq *0xfff.. with the wrmsrl
assembler code.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Currently, KVM flushes the TLB after a change to the APIC access page
address or the APIC mode when EPT mode is enabled. However, even in
shadow paging mode, a TLB flush is needed if VPIDs are being used, as
specified in the Intel SDM Section 29.4.5.
So replace vmx_flush_tlb_ept_only() with vmx_flush_tlb(), which will
flush if either EPT or VPIDs are in use.
Signed-off-by: Junaid Shahid <junaids@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
writing nested virtualization tests.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull kvm fixes from Paolo Bonzini:
"Bug fixes, plus a new test case and the associated infrastructure for
writing nested virtualization tests"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
kvm: selftests: add vmx_tsc_adjust_test
kvm: x86: move MSR_IA32_TSC handling to x86.c
X86/KVM: Properly update 'tsc_offset' to represent the running guest
kvm: selftests: add -std=gnu99 cflags
x86: Add check for APIC access address for vmentry of L2 guests
KVM: X86: fix incorrect reference of trace_kvm_pi_irte_update
X86/KVM: Do not allow DISABLE_EXITS_MWAIT when LAPIC ARAT is not available
kvm: selftests: fix spelling mistake: "divisable" and "divisible"
X86/VMX: Disable VMX preemption timer if MWAIT is not intercepted
Update 'tsc_offset' on vmentry/vmexit of L2 guests to ensure that it always
captures the TSC_OFFSET of the running guest whether it is the L1 or L2
guest.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Jim Mattson <jmattson@google.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
[AMD changes, fix update_ia32_tsc_adjust_msr. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
According to the sub-section titled 'VM-Execution Control Fields' in the
section titled 'Basic VM-Entry Checks' in Intel SDM vol. 3C, the following
vmentry check must be enforced:
If the 'virtualize APIC-accesses' VM-execution control is 1, the
APIC-access address must satisfy the following checks:
- Bits 11:0 of the address must be 0.
- The address should not set any bits beyond the processor's
physical-address width.
This patch adds the necessary check to conform to this rule. If the check
fails, we cause the L2 VMENTRY to fail which is what the associated unit
test (following patch) expects.
Reviewed-by: Mihai Carabas <mihai.carabas@oracle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
In arch/x86/kvm/trace.h, this function is declared as host_irq the
first input, and vcpu_id the second, instead of otherwise.
Signed-off-by: hu huajun <huhuajun@linux.alibaba.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The VMX-preemption timer is used by KVM as a way to set deadlines for the
guest (i.e. timer emulation). That was safe till very recently when
capability KVM_X86_DISABLE_EXITS_MWAIT to disable intercepting MWAIT was
introduced. According to Intel SDM 25.5.1:
"""
The VMX-preemption timer operates in the C-states C0, C1, and C2; it also
operates in the shutdown and wait-for-SIPI states. If the timer counts down
to zero in any state other than the wait-for SIPI state, the logical
processor transitions to the C0 C-state and causes a VM exit; the timer
does not cause a VM exit if it counts down to zero in the wait-for-SIPI
state. The timer is not decremented in C-states deeper than C2.
"""
Now once the guest issues the MWAIT with a c-state deeper than
C2 the preemption timer will never wake it up again since it stopped
ticking! Usually this is compensated by other activities in the system that
would wake the core from the deep C-state (and cause a VMExit). For
example, if the host itself is ticking or it received interrupts, etc!
So disable the VMX-preemption timer if MWAIT is exposed to the guest!
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: kvm@vger.kernel.org
Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
Fixes: 4d5422cea3
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
- VHE optimizations
- EL2 address space randomization
- speculative execution mitigations ("variant 3a", aka execution past invalid
privilege register access)
- bugfixes and cleanups
PPC:
- improvements for the radix page fault handler for HV KVM on POWER9
s390:
- more kvm stat counters
- virtio gpu plumbing
- documentation
- facilities improvements
x86:
- support for VMware magic I/O port and pseudo-PMCs
- AMD pause loop exiting
- support for AMD core performance extensions
- support for synchronous register access
- expose nVMX capabilities to userspace
- support for Hyper-V signaling via eventfd
- use Enlightened VMCS when running on Hyper-V
- allow userspace to disable MWAIT/HLT/PAUSE vmexits
- usual roundup of optimizations and nested virtualization bugfixes
Generic:
- API selftest infrastructure (though the only tests are for x86 as of now)
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull kvm updates from Paolo Bonzini:
"ARM:
- VHE optimizations
- EL2 address space randomization
- speculative execution mitigations ("variant 3a", aka execution past
invalid privilege register access)
- bugfixes and cleanups
PPC:
- improvements for the radix page fault handler for HV KVM on POWER9
s390:
- more kvm stat counters
- virtio gpu plumbing
- documentation
- facilities improvements
x86:
- support for VMware magic I/O port and pseudo-PMCs
- AMD pause loop exiting
- support for AMD core performance extensions
- support for synchronous register access
- expose nVMX capabilities to userspace
- support for Hyper-V signaling via eventfd
- use Enlightened VMCS when running on Hyper-V
- allow userspace to disable MWAIT/HLT/PAUSE vmexits
- usual roundup of optimizations and nested virtualization bugfixes
Generic:
- API selftest infrastructure (though the only tests are for x86 as
of now)"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (174 commits)
kvm: x86: fix a prototype warning
kvm: selftests: add sync_regs_test
kvm: selftests: add API testing infrastructure
kvm: x86: fix a compile warning
KVM: X86: Add Force Emulation Prefix for "emulate the next instruction"
KVM: X86: Introduce handle_ud()
KVM: vmx: unify adjacent #ifdefs
x86: kvm: hide the unused 'cpu' variable
KVM: VMX: remove bogus WARN_ON in handle_ept_misconfig
Revert "KVM: X86: Fix SMRAM accessing even if VM is shutdown"
kvm: Add emulation for movups/movupd
KVM: VMX: raise internal error for exception during invalid protected mode state
KVM: nVMX: Optimization: Dont set KVM_REQ_EVENT when VMExit with nested_run_pending
KVM: nVMX: Require immediate-exit when event reinjected to L2 and L1 event pending
KVM: x86: Fix misleading comments on handling pending exceptions
KVM: x86: Rename interrupt.pending to interrupt.injected
KVM: VMX: No need to clear pending NMI/interrupt on inject realmode interrupt
x86/kvm: use Enlightened VMCS when running on Hyper-V
x86/hyper-v: detect nested features
x86/hyper-v: define struct hv_enlightened_vmcs and clean field bits
...
Make the function static to avoid a
warning: no previous prototype for ‘vmx_enable_tdp’
Signed-off-by: Peng Hao <peng.hao2@zte.com.cn>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Introduce handle_ud() to handle invalid opcode, this function will be
used by later patches.
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Liran Alon <liran.alon@oracle.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim KrÄmář <rkrcmar@redhat.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
vmx_save_host_state has multiple ifdefs for CONFIG_X86_64 that have
no other code between them. Simplify by reducing them to a single
conditional.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The local variable was newly introduced but is only accessed in one
place on x86_64, but not on 32-bit:
arch/x86/kvm/vmx.c: In function 'vmx_save_host_state':
arch/x86/kvm/vmx.c:2175:6: error: unused variable 'cpu' [-Werror=unused-variable]
This puts it into another #ifdef.
Fixes: 35060ed6a1 ("x86/kvm/vmx: avoid expensive rdmsr for MSR_GS_BASE")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Remove the WARN_ON in handle_ept_misconfig() as it is unnecessary
and causes false positives. Return the unmodified result of
kvm_mmu_page_fault() instead of converting a system error code to
KVM_EXIT_UNKNOWN so that userspace sees the error code of the
actual failure, not a generic "we don't know what went wrong".
* kvm_mmu_page_fault() will WARN if reserved bits are set in the
SPTEs, i.e. it covers the case where an EPT misconfig occurred
because of a KVM bug.
* The WARN_ON will fire on any system error code that is hit while
handling the fault, e.g. -ENOMEM from mmu_topup_memory_caches()
while handling a legitmate MMIO EPT misconfig or -EFAULT from
kvm_handle_bad_page() if the corresponding HVA is invalid. In
either case, userspace should receive the original error code
and firing a warning is incorrect behavior as KVM is operating
as designed.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Exit to userspace with KVM_INTERNAL_ERROR_EMULATION if we encounter
an exception in Protected Mode while emulating guest due to invalid
guest state. Unlike Big RM, KVM doesn't support emulating exceptions
in PM, i.e. PM exceptions are always injected via the VMCS. Because
we will never do VMRESUME due to emulation_required, the exception is
never realized and we'll keep emulating the faulting instruction over
and over until we receive a signal.
Exit to userspace iff there is a pending exception, i.e. don't exit
simply on a requested event. The purpose of this check and exit is to
aid in debugging a guest that is in all likelihood already doomed.
Invalid guest state in PM is extremely limited in normal operation,
e.g. it generally only occurs for a few instructions early in BIOS,
and any exception at this time is all but guaranteed to be fatal.
Non-vectored interrupts, e.g. INIT, SIPI and SMI, can be cleanly
handled/emulated, while checking for vectored interrupts, e.g. INTR
and NMI, without hitting false positives would add a fair amount of
complexity for almost no benefit (getting hit by lightning seems
more likely than encountering this specific scenario).
Add a WARN_ON_ONCE to vmx_queue_exception() if we try to inject an
exception via the VMCS and emulation_required is true.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Pull x86 cleanups and msr updates from Ingo Molnar:
"The main change is a performance/latency improvement to /dev/msr
access. The rest are misc cleanups"
* 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/msr: Make rdmsrl_safe_on_cpu() scheduling safe as well
x86/cpuid: Allow cpuid_read() to schedule
x86/msr: Allow rdmsr_safe_on_cpu() to schedule
x86/rtc: Stop using deprecated functions
x86/dumpstack: Unify show_regs()
x86/fault: Do not print IP in show_fault_oops()
x86/MSR: Move native_* variants to msr.h
PPC:
- Fix a bug causing occasional machine check exceptions on POWER8 hosts
(introduced in 4.16-rc1)
x86:
- Fix a guest crashing regression with nested VMX and restricted guest
(introduced in 4.16-rc1)
- Fix dependency check for pv tlb flush (The wrong dependency that
effectively disabled the feature was added in 4.16-rc4, the original
feature in 4.16-rc1, so it got decent testing.)
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM fixes from Radim Krčmář:
"PPC:
- Fix a bug causing occasional machine check exceptions on POWER8
hosts (introduced in 4.16-rc1)
x86:
- Fix a guest crashing regression with nested VMX and restricted
guest (introduced in 4.16-rc1)
- Fix dependency check for pv tlb flush (the wrong dependency that
effectively disabled the feature was added in 4.16-rc4, the
original feature in 4.16-rc1, so it got decent testing)"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: x86: Fix pv tlb flush dependencies
KVM: nVMX: sync vmcs02 segment regs prior to vmx_set_cr0
KVM: PPC: Book3S HV: Fix duplication of host SLB entries
