diff options
Diffstat (limited to 'arch/x86/kvm/cpuid.h')
| -rw-r--r-- | arch/x86/kvm/cpuid.h | 45 |
1 files changed, 36 insertions, 9 deletions
diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h index d78a61408243..7366c618aa04 100644 --- a/arch/x86/kvm/cpuid.h +++ b/arch/x86/kvm/cpuid.h @@ -53,15 +53,46 @@ static const struct cpuid_reg reverse_cpuid[] = { [CPUID_7_ECX] = { 7, 0, CPUID_ECX}, [CPUID_8000_0007_EBX] = {0x80000007, 0, CPUID_EBX}, [CPUID_7_EDX] = { 7, 0, CPUID_EDX}, + [CPUID_7_1_EAX] = { 7, 1, CPUID_EAX}, }; -static __always_inline struct cpuid_reg x86_feature_cpuid(unsigned x86_feature) +/* + * Reverse CPUID and its derivatives can only be used for hardware-defined + * feature words, i.e. words whose bits directly correspond to a CPUID leaf. + * Retrieving a feature bit or masking guest CPUID from a Linux-defined word + * is nonsensical as the bit number/mask is an arbitrary software-defined value + * and can't be used by KVM to query/control guest capabilities. And obviously + * the leaf being queried must have an entry in the lookup table. + */ +static __always_inline void reverse_cpuid_check(unsigned x86_leaf) { - unsigned x86_leaf = x86_feature / 32; - + BUILD_BUG_ON(x86_leaf == CPUID_LNX_1); + BUILD_BUG_ON(x86_leaf == CPUID_LNX_2); + BUILD_BUG_ON(x86_leaf == CPUID_LNX_3); + BUILD_BUG_ON(x86_leaf == CPUID_LNX_4); BUILD_BUG_ON(x86_leaf >= ARRAY_SIZE(reverse_cpuid)); BUILD_BUG_ON(reverse_cpuid[x86_leaf].function == 0); +} + +/* + * Retrieve the bit mask from an X86_FEATURE_* definition. Features contain + * the hardware defined bit number (stored in bits 4:0) and a software defined + * "word" (stored in bits 31:5). The word is used to index into arrays of + * bit masks that hold the per-cpu feature capabilities, e.g. this_cpu_has(). + */ +static __always_inline u32 __feature_bit(int x86_feature) +{ + reverse_cpuid_check(x86_feature / 32); + return 1 << (x86_feature & 31); +} +#define feature_bit(name) __feature_bit(X86_FEATURE_##name) + +static __always_inline struct cpuid_reg x86_feature_cpuid(unsigned x86_feature) +{ + unsigned x86_leaf = x86_feature / 32; + + reverse_cpuid_check(x86_leaf); return reverse_cpuid[x86_leaf]; } @@ -93,15 +124,11 @@ static __always_inline bool guest_cpuid_has(struct kvm_vcpu *vcpu, unsigned x86_ { int *reg; - if (x86_feature == X86_FEATURE_XSAVE && - !static_cpu_has(X86_FEATURE_XSAVE)) - return false; - reg = guest_cpuid_get_register(vcpu, x86_feature); if (!reg) return false; - return *reg & bit(x86_feature); + return *reg & __feature_bit(x86_feature); } static __always_inline void guest_cpuid_clear(struct kvm_vcpu *vcpu, unsigned x86_feature) @@ -110,7 +137,7 @@ static __always_inline void guest_cpuid_clear(struct kvm_vcpu *vcpu, unsigned x8 reg = guest_cpuid_get_register(vcpu, x86_feature); if (reg) - *reg &= ~bit(x86_feature); + *reg &= ~__feature_bit(x86_feature); } static inline bool guest_cpuid_is_amd(struct kvm_vcpu *vcpu) |