From: Josh Poimboeuf jpoimboe@kernel.org
mainline inclusion from mainline-v6.6-rc3 commit 02428d0366a27c2f33bc4361eb10467777804f29 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I9NZ3E
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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To support live migration, the hypervisor sets the "lowest common denominator" of features. Probing the microcode isn't allowed because any detected features might go away after a migration.
As Andy Cooper states:
"Linux must not probe microcode when virtualised. What it may see instantaneously on boot (owing to MSR_PRED_CMD being fully passed through) is not accurate for the lifetime of the VM."
Rely on the hypervisor to set the needed IBPB_BRTYPE and SBPB bits.
Fixes: 1b5277c0ea0b ("x86/srso: Add SRSO_NO support") Suggested-by: Andrew Cooper andrew.cooper3@citrix.com Signed-off-by: Josh Poimboeuf jpoimboe@kernel.org Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Reviewed-by: Andrew Cooper andrew.cooper3@citrix.com Acked-by: Borislav Petkov (AMD) bp@alien8.de Link: https://lore.kernel.org/r/3938a7209606c045a3f50305d201d840e8c834c7.169388998... Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- arch/x86/kernel/cpu/amd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index 99c860947fc6..f9cbb25c55d3 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -784,7 +784,7 @@ static void early_init_amd(struct cpuinfo_x86 *c) if (cpu_has(c, X86_FEATURE_TOPOEXT)) smp_num_siblings = ((cpuid_ebx(0x8000001e) >> 8) & 0xff) + 1;
- if (!cpu_has(c, X86_FEATURE_IBPB_BRTYPE)) { + if (!cpu_has(c, X86_FEATURE_HYPERVISOR) && !cpu_has(c, X86_FEATURE_IBPB_BRTYPE)) { if (c->x86 == 0x17 && boot_cpu_has(X86_FEATURE_AMD_IBPB)) setup_force_cpu_cap(X86_FEATURE_IBPB_BRTYPE); else if (c->x86 >= 0x19 && !wrmsrl_safe(MSR_IA32_PRED_CMD, PRED_CMD_SBPB)) {