diff options
Diffstat (limited to 'arch/x86/kvm/cpuid.c')
| -rw-r--r-- | arch/x86/kvm/cpuid.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index aa3a6dc74e95..12455dc5afe5 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -742,12 +742,22 @@ void kvm_set_cpu_caps(void) F(SME_COHERENT)); kvm_cpu_cap_mask(CPUID_8000_0021_EAX, - F(NO_NESTED_DATA_BP) | - BIT(2) /* LFENCE Always serializing */ | 0 /* SmmPgCfgLock */ | + F(NO_NESTED_DATA_BP) | F(LFENCE_RDTSC) | 0 /* SmmPgCfgLock */ | BIT(6) /* NULL_SEL_CLR_BASE */ | 0 /* PrefetchCtlMsr */ ); + + /* + * Synthesize "LFENCE is serializing" into the AMD-defined entry in + * KVM's supported CPUID if the feature is reported as supported by the + * kernel. LFENCE_RDTSC was a Linux-defined synthetic feature long + * before AMD joined the bandwagon, e.g. LFENCE is serializing on most + * CPUs that support SSE2. On CPUs that don't support AMD's leaf, + * kvm_cpu_cap_mask() will unfortunately drop the flag due to ANDing + * the mask with the raw host CPUID, and reporting support in AMD's + * leaf can make it easier for userspace to detect the feature. + */ if (cpu_feature_enabled(X86_FEATURE_LFENCE_RDTSC)) - kvm_cpu_caps[CPUID_8000_0021_EAX] |= BIT(2) /* LFENCE Always serializing */; + kvm_cpu_cap_set(X86_FEATURE_LFENCE_RDTSC); if (!static_cpu_has_bug(X86_BUG_NULL_SEG)) kvm_cpu_caps[CPUID_8000_0021_EAX] |= BIT(6) /* NULL_SEL_CLR_BASE */; kvm_cpu_caps[CPUID_8000_0021_EAX] |= BIT(9) /* NO_SMM_CTL_MSR */; |