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Anand K Mistry 1978b3a53a x86/speculation: Allow IBPB to be conditionally enabled on CPUs with always-on STIBP 
On AMD CPUs which have the feature X86_FEATURE_AMD_STIBP_ALWAYS_ON,
STIBP is set to on and

  spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT_PREFERRED

At the same time, IBPB can be set to conditional.

However, this leads to the case where it's impossible to turn on IBPB
for a process because in the PR_SPEC_DISABLE case in ib_prctl_set() the

  spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT_PREFERRED

condition leads to a return before the task flag is set. Similarly,
ib_prctl_get() will return PR_SPEC_DISABLE even though IBPB is set to
conditional.

More generally, the following cases are possible:

1. STIBP = conditional && IBPB = on for spectre_v2_user=seccomp,ibpb
2. STIBP = on && IBPB = conditional for AMD CPUs with
   X86_FEATURE_AMD_STIBP_ALWAYS_ON

The first case functions correctly today, but only because
spectre_v2_user_ibpb isn't updated to reflect the IBPB mode.

At a high level, this change does one thing. If either STIBP or IBPB
is set to conditional, allow the prctl to change the task flag.
Also, reflect that capability when querying the state. This isn't
perfect since it doesn't take into account if only STIBP or IBPB is
unconditionally on. But it allows the conditional feature to work as
expected, without affecting the unconditional one.

 [ bp: Massage commit message and comment; space out statements for
   better readability. ]

Fixes: 21998a3515 ("x86/speculation: Avoid force-disabling IBPB based on STIBP and enhanced IBRS.")
Signed-off-by: Anand K Mistry <amistry@google.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lkml.kernel.org/r/20201105163246.v2.1.Ifd7243cd3e2c2206a893ad0a5b9a4f19549e22c6@changeid
2020-11-05 21:43:34 +01:00
..
acpi mm: reorder includes after introduction of linux/pgtable.h 2020-06-09 09:39:13 -07:00
apic Surgery of the MSI interrupt handling to prepare the support of upcoming 2020-10-12 11:40:41 -07:00
cpu x86/speculation: Allow IBPB to be conditionally enabled on CPUs with always-on STIBP 2020-11-05 21:43:34 +01:00
fpu * Allow clearcpuid= to accept multiple bits, by Arvind Sankar. 2020-10-12 10:49:46 -07:00
kprobes objtool changes for v5.10: 2020-10-14 10:13:37 -07:00
.gitignore .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
alternative.c A couple of x86 fixes which missed rc1 due to my stupidity: 2020-10-27 14:39:29 -07:00
amd_gart_64.c dma-mapping: split <linux/dma-mapping.h> 2020-10-06 07:07:03 +02:00
amd_nb.c x86/amd_nb: Add AMD family 17h model 60h PCI IDs 2020-05-22 18:24:40 +02:00
apb_timer.c x86/apb_timer: Drop unused TSC calibration 2020-05-27 13:05:59 +02:00
aperture_64.c x86/gart: Exclude GART aperture from kcore 2019-03-23 12:11:49 +01:00
apm_32.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 118 2019-05-24 17:39:02 +02:00
asm-offsets.c x86: remove address space overrides using set_fs() 2020-09-08 22:21:36 -04:00
asm-offsets_32.c x86 entry code updates: 2020-03-30 19:14:28 -07:00
asm-offsets_64.c x86/entry: Remove DBn stacks 2020-06-11 15:15:23 +02:00
audit_64.c x86/audit: Fix a -Wmissing-prototypes warning for ia32_classify_syscall() 2020-05-19 18:03:07 +02:00
bootflag.c
check.c
cpuid.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 142 2019-05-30 11:25:17 -07:00
crash.c x86/crash: Correct the address boundary of function parameters 2020-08-07 01:32:00 +02:00
crash_core_32.c mm: reorder includes after introduction of linux/pgtable.h 2020-06-09 09:39:13 -07:00
crash_core_64.c mm: reorder includes after introduction of linux/pgtable.h 2020-06-09 09:39:13 -07:00
crash_dump_32.c
crash_dump_64.c fs/core/vmcore: Move sev_active() reference to x86 arch code 2019-08-09 22:52:10 +10:00
devicetree.c x86_ioapic_Consolidate_IOAPIC_allocation 2020-09-16 16:52:32 +02:00
doublefault_32.c x86/entry: Convert double fault exception to IDTENTRY_DF 2020-06-11 15:15:03 +02:00
dumpstack.c This feature enhances the current guest memory encryption support 2020-10-14 10:21:34 -07:00
dumpstack_32.c x86/32: Remove CONFIG_DOUBLEFAULT 2020-04-14 14:24:05 +02:00
dumpstack_64.c x86/dumpstack/64: Add noinstr version of get_stack_info() 2020-09-09 11:33:19 +02:00
e820.c efi/fake_mem: arrange for a resource entry per efi_fake_mem instance 2020-10-13 18:38:27 -07:00
early-quirks.c x86/gpu: add RKL stolen memory support 2020-05-20 08:35:22 -07:00
early_printk.c mm: reorder includes after introduction of linux/pgtable.h 2020-06-09 09:39:13 -07:00
ebda.c
eisa.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 243 2019-06-19 17:09:07 +02:00
espfix_64.c mm: introduce include/linux/pgtable.h 2020-06-09 09:39:13 -07:00
ftrace.c x86/ftrace: Do not jump to direct code in created trampolines 2020-06-29 11:42:48 -04:00
ftrace_32.S x86: Change {JMP,CALL}_NOSPEC argument 2020-04-30 20:14:34 +02:00
ftrace_64.S x86/ftrace: Do not jump to direct code in created trampolines 2020-06-29 11:42:48 -04:00
head32.c
head64.c treewide: Convert macro and uses of __section(foo) to __section("foo") 2020-10-25 14:51:49 -07:00
head_32.S x86/xen: remove 32-bit Xen PV guest support 2020-08-11 08:26:48 +02:00
head_64.S x86/head/64: Don't call verify_cpu() on starting APs 2020-09-09 11:33:20 +02:00
hpet.c remove ioremap_nocache and devm_ioremap_nocache 2020-01-06 09:45:59 +01:00
hw_breakpoint.c x86/debug: Change thread.debugreg6 to thread.virtual_dr6 2020-09-04 15:12:58 +02:00
i8237.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
i8253.c x86/timer: Skip PIT initialization on modern chipsets 2019-06-29 11:35:35 +02:00
i8259.c x86/i8259: Use printk_deferred() to prevent deadlock 2020-07-29 16:27:16 +02:00
idt.c This feature enhances the current guest memory encryption support 2020-10-14 10:21:34 -07:00
ima_arch.c EFI updates for v5.7: 2020-02-26 15:21:22 +01:00
io_delay.c x86/io_delay: Define IO_DELAY macros in C instead of Kconfig 2019-05-24 08:46:06 +02:00
ioport.c x86/ioperm: Prevent a memory leak when fork fails 2020-05-28 21:36:20 +02:00
irq.c x86/irq: Make run_on_irqstack_cond() typesafe 2020-09-22 22:13:34 +02:00
irq_32.c x86/irq: Rework handle_irq() for 64-bit 2020-06-11 15:15:12 +02:00
irq_64.c x86/irq: Make run_on_irqstack_cond() typesafe 2020-09-22 22:13:34 +02:00
irq_work.c x86/entry: Convert various system vectors 2020-06-11 15:15:14 +02:00
irqflags.S x86/asm: Change all ENTRY+ENDPROC to SYM_FUNC_* 2019-10-18 11:58:33 +02:00
irqinit.c x86/headers: Remove APIC headers from <asm/smp.h> 2020-08-06 16:13:09 +02:00
itmt.c sysctl: pass kernel pointers to ->proc_handler 2020-04-27 02:07:40 -04:00
jailhouse.c locking/seqlock, headers: Untangle the spaghetti monster 2020-08-06 16:13:13 +02:00
jump_label.c x86/jump_label: Move 'inline' keyword placement 2020-03-27 11:05:41 +01:00
kdebugfs.c x86/boot: Introduce setup_indirect 2019-11-12 16:21:15 +01:00
kexec-bzimage64.c x86/kexec: Use up-to-dated screen_info copy to fill boot params 2020-10-14 17:05:03 +02:00
kgdb.c x86/debug: Change thread.debugreg6 to thread.virtual_dr6 2020-09-04 15:12:58 +02:00
ksysfs.c x86/boot: Introduce setup_indirect 2019-11-12 16:21:15 +01:00
kvm.c ARM: 2020-10-23 11:17:56 -07:00
kvmclock.c x86/vdso: Use generic VDSO clock mode storage 2020-02-17 14:40:23 +01:00
ldt.c x86/ldt: use "pr_info_once()" instead of open-coding it badly 2020-07-05 12:50:20 -07:00
machine_kexec_32.c mm: don't include asm/pgtable.h if linux/mm.h is already included 2020-06-09 09:39:13 -07:00
machine_kexec_64.c mm: don't include asm/pgtable.h if linux/mm.h is already included 2020-06-09 09:39:13 -07:00
Makefile x86/head/64: Disable stack protection for head$(BITS).o 2020-10-19 13:11:00 +02:00
mmconf-fam10h_64.c
module.c mm: don't include asm/pgtable.h if linux/mm.h is already included 2020-06-09 09:39:13 -07:00
mpparse.c Surgery of the MSI interrupt handling to prepare the support of upcoming 2020-10-12 11:40:41 -07:00
msr.c x86/msr: Make source of unrecognised MSR writes unambiguous 2020-08-22 11:40:38 +02:00
nmi.c This feature enhances the current guest memory encryption support 2020-10-14 10:21:34 -07:00
nmi_selftest.c
paravirt-spinlocks.c
paravirt.c x86/paravirt: Remove set_pte_at() pv-op 2020-08-15 13:52:12 +02:00
paravirt_patch.c x86/paravirt: Remove 32-bit support from CONFIG_PARAVIRT_XXL 2020-08-15 13:52:11 +02:00
pci-dma.c dma-mapping: move dma-debug.h to kernel/dma/ 2020-10-06 07:07:05 +02:00
pci-iommu_table.c
pci-swiotlb.c dma-mapping: fix filename references 2019-09-03 08:36:30 +02:00
pcspeaker.c
perf_regs.c perf/x86/regs: Check reserved bits 2019-06-24 19:19:24 +02:00
platform-quirks.c
pmem.c
probe_roms.c maccess: make get_kernel_nofault() check for minimal type compatibility 2020-06-18 12:10:37 -07:00
process.c x86/unwind/fp: Fix FP unwinding in ret_from_fork 2020-09-18 09:59:40 +02:00
process.h x86: Use the correct SPDX License Identifier in headers 2019-10-01 20:31:35 +02:00
process_32.c x86/dumpstack: Add log_lvl to __show_regs() 2020-07-22 23:56:53 +02:00
process_64.c x86/fsgsbase: Replace static_cpu_has() with boot_cpu_has() 2020-08-24 18:18:32 +02:00
ptrace.c x86/debug: Change thread.debugreg6 to thread.virtual_dr6 2020-09-04 15:12:58 +02:00
pvclock.c x86/vdso: Use generic VDSO clock mode storage 2020-02-17 14:40:23 +01:00
quirks.c x86, powerpc: Rename memcpy_mcsafe() to copy_mc_to_{user, kernel}() 2020-10-06 11:18:04 +02:00
reboot.c objtool: Rename frame.h -> objtool.h 2020-09-10 10:43:13 -05:00
reboot_fixups_32.c
relocate_kernel_32.S x86/asm: Annotate relocate_kernel_{32,64}.c 2019-10-18 09:53:19 +02:00
relocate_kernel_64.S x86/kexec: Make relocate_kernel_64.S objtool clean 2020-03-25 18:28:28 +01:00
resource.c
rtc.c
setup.c dma-mapping updates for 5.10 2020-10-15 14:43:29 -07:00
setup_percpu.c x86/mm: remove vmalloc faulting 2020-06-02 10:59:12 -07:00
sev-es-shared.c x86/sev-es: Check required CPU features for SEV-ES 2020-09-10 21:49:25 +02:00
sev-es.c x86/sev-es: Use GHCB accessor for setting the MMIO scratch buffer 2020-09-25 17:12:41 +02:00
signal.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
signal_compat.c arm64: mte: Add specific SIGSEGV codes 2020-09-04 12:46:06 +01:00
smp.c x86/entry: Convert reschedule interrupt to IDTENTRY_SYSVEC_SIMPLE 2020-06-11 15:15:16 +02:00
smpboot.c x86/smpboot: Load TSS and getcpu GDT entry before loading IDT 2020-09-09 11:33:20 +02:00
stacktrace.c stacktrace: Remove reliable argument from arch_stack_walk() callback 2020-09-18 14:24:16 +01:00
static_call.c static_call: Allow early init 2020-09-01 09:58:06 +02:00
step.c
sys_ia32.c x86: switch to kernel_clone() 2020-08-20 13:12:58 +02:00
sys_x86_64.c x86: Remove unneeded includes 2020-03-21 16:03:25 +01:00
sysfb.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
sysfb_efi.c x86/sysfb_efi: Add quirks for some devices with swapped width and height 2019-07-22 10:47:11 +02:00
sysfb_simplefb.c x86/sysfb: Fix check for bad VRAM size 2020-01-20 10:57:53 +01:00
tboot.c mmap locking API: add MMAP_LOCK_INITIALIZER 2020-06-09 09:39:14 -07:00
time.c A set of fixes and updates for x86: 2020-06-11 15:54:31 -07:00
tls.c x86: switch to ->regset_get() 2020-07-27 14:31:07 -04:00
tls.h x86: switch to ->regset_get() 2020-07-27 14:31:07 -04:00
topology.c x86/headers: Remove APIC headers from <asm/smp.h> 2020-08-06 16:13:09 +02:00
trace_clock.c
tracepoint.c x86/entry: Convert reschedule interrupt to IDTENTRY_SYSVEC_SIMPLE 2020-06-11 15:15:16 +02:00
traps.c x86/debug: Fix DR_STEP vs ptrace_get_debugreg(6) 2020-10-27 23:15:24 +01:00
tsc.c x86/tsc: Use seqcount_latch_t 2020-09-10 11:19:29 +02:00
tsc_msr.c Misc fixes and small updates all around the place: 2020-08-15 10:38:03 -07:00
tsc_sync.c x86: Fix a handful of typos 2020-02-16 20:58:06 +01:00
umip.c x86/umip: Factor out instruction decoding 2020-09-07 19:45:24 +02:00
unwind_frame.c fork-v5.9 2020-08-04 14:47:45 -07:00
unwind_guess.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
unwind_orc.c A couple of x86 fixes which missed rc1 due to my stupidity: 2020-10-27 14:39:29 -07:00
uprobes.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
verify_cpu.S x86/asm: Annotate local pseudo-functions 2019-10-18 10:04:04 +02:00
vm86_32.c mmap locking API: use coccinelle to convert mmap_sem rwsem call sites 2020-06-09 09:39:14 -07:00
vmlinux.lds.S This tree introduces static_call(), which is the idea of static_branch() 2020-10-12 13:58:15 -07:00
vsmp_64.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 346 2019-06-05 17:37:08 +02:00
x86_init.c x86/irq: Cleanup the arch_*_msi_irqs() leftovers 2020-09-16 16:52:38 +02:00