diff options
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kvm/cpuid.c | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index f0d5ac7a12c9..32007f902bba 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -723,6 +723,19 @@ static struct kvm_cpuid_entry2 *do_host_cpuid(struct kvm_cpuid_array *array, /* Hypervisor leaves are always synthesized by __do_cpuid_func. */ return entry; + case 0x80000000: + /* + * 0x80000021 is sometimes synthesized by __do_cpuid_func, which + * would result in out-of-bounds calls to do_host_cpuid. + */ + { + static int max_cpuid_80000000; + if (!READ_ONCE(max_cpuid_80000000)) + WRITE_ONCE(max_cpuid_80000000, cpuid_eax(0x80000000)); + if (function > READ_ONCE(max_cpuid_80000000)) + return entry; + } + default: break; } @@ -1069,6 +1082,14 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) break; case 0x80000000: entry->eax = min(entry->eax, 0x80000021); + /* + * Serializing LFENCE is reported in a multitude of ways, + * and NullSegClearsBase is not reported in CPUID on Zen2; + * help userspace by providing the CPUID leaf ourselves. + */ + if (static_cpu_has(X86_FEATURE_LFENCE_RDTSC) + || !static_cpu_has_bug(X86_BUG_NULL_SEG)) + entry->eax = max(entry->eax, 0x80000021); break; case 0x80000001: cpuid_entry_override(entry, CPUID_8000_0001_EDX); @@ -1155,6 +1176,10 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) * EAX 13 PCMSR, Prefetch control MSR */ entry->eax &= BIT(0) | BIT(2) | BIT(6); + if (static_cpu_has(X86_FEATURE_LFENCE_RDTSC)) + entry->eax |= BIT(2); + if (!static_cpu_has_bug(X86_BUG_NULL_SEG)) + entry->eax |= BIT(6); break; /*Add support for Centaur's CPUID instruction*/ case 0xC0000000: |