The Null Selector Clears Base feature was being open-coded for KVM in __do_cpuid_func(). Add it to its newly added CPUID leaf 0x80000021 EAX proper, and propagate it in kvm_set_cpu_caps() instead. Also drop the bit description comments now it's more self-describing. Signed-off-by: Kim Phillips <kim.phillips@xxxxxxx> --- arch/x86/include/asm/cpufeatures.h | 1 + arch/x86/kvm/cpuid.c | 10 +++------- 2 files changed, 4 insertions(+), 7 deletions(-) diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index 79da8e492c0f..8237c4cc4010 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -429,6 +429,7 @@ /* AMD-defined Extended Feature 2 EAX, CPUID level 0x80000021 (EAX), word 20 */ #define X86_FEATURE_NO_NESTED_DATA_BP (20*32+ 0) /* "" AMD No Nested Data Breakpoints */ #define X86_FEATURE_LFENCE_RDTSC (20*32+ 2) /* "" LFENCE always serializing / synchronizes RDTSC */ +#define X86_FEATURE_NULL_SEL_CLR_BASE (20*32+ 6) /* "" AMD Null Selector Clears Base */ /* * BUG word(s) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 88c970046c10..04f2f4879d69 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -742,10 +742,12 @@ void kvm_set_cpu_caps(void) F(SME_COHERENT)); kvm_cpu_cap_mask(CPUID_8000_0021_EAX, - F(NO_NESTED_DATA_BP) | F(LFENCE_RDTSC) + F(NO_NESTED_DATA_BP) | F(LFENCE_RDTSC) | F(NULL_SEL_CLR_BASE) ); if (cpu_feature_enabled(X86_FEATURE_LFENCE_RDTSC)) kvm_cpu_cap_set(X86_FEATURE_LFENCE_RDTSC); + if (!static_cpu_has_bug(X86_BUG_NULL_SEG)) + kvm_cpu_cap_set(X86_FEATURE_NULL_SEL_CLR_BASE); kvm_cpu_cap_mask(CPUID_C000_0001_EDX, F(XSTORE) | F(XSTORE_EN) | F(XCRYPT) | F(XCRYPT_EN) | @@ -1230,9 +1232,6 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) entry->ebx = entry->ecx = entry->edx = 0; cpuid_entry_override(entry, CPUID_8000_0021_EAX); /* - * Pass down these bits: - * EAX 6 NSCB, Null selector clear base - * * Other defined bits are for MSRs that KVM does not expose: * EAX 3 SPCL, SMM page configuration lock * EAX 13 PCMSR, Prefetch control MSR @@ -1240,10 +1239,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) * KVM doesn't support SMM_CTL. * EAX 9 SMM_CTL MSR is not supported */ - entry->eax &= BIT(6); entry->eax |= BIT(9); - if (!static_cpu_has_bug(X86_BUG_NULL_SEG)) - entry->eax |= BIT(6); break; /*Add support for Centaur's CPUID instruction*/ case 0xC0000000: -- 2.34.1
