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SubjectRe: [PATCH 1/8] KVM: x86: add SPEC_CTRL and IBPB_SUPPORT accessors
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On 09.01.2018 13:03, Paolo Bonzini wrote:
> As an interim measure until SPEC_CTRL is supported by upstream
> Linux in cpufeatures, add a function that lets vmx.c and svm.c
> know whether to save/restore MSR_IA32_SPEC_CTRL.
>
> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> arch/x86/kvm/cpuid.c | 3 ---
> arch/x86/kvm/cpuid.h | 22 ++++++++++++++++++++++
> 2 files changed, 22 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 8e9a07c557f1..767af697c20c 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -67,9 +67,6 @@ u64 kvm_supported_xcr0(void)
>
> #define F(x) bit(X86_FEATURE_##x)
>
> -/* These are scattered features in cpufeatures.h. */
> -#define KVM_CPUID_BIT_AVX512_4VNNIW 2
> -#define KVM_CPUID_BIT_AVX512_4FMAPS 3
> #define KF(x) bit(KVM_CPUID_BIT_##x)
>
> int kvm_update_cpuid(struct kvm_vcpu *vcpu)
> diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
> index c2cea6651279..8d04ccf177ce 100644
> --- a/arch/x86/kvm/cpuid.h
> +++ b/arch/x86/kvm/cpuid.h
> @@ -155,6 +155,28 @@ static inline int guest_cpuid_stepping(struct kvm_vcpu *vcpu)
> return x86_stepping(best->eax);
> }
>
> +/* These are scattered features in cpufeatures.h. */
> +#define KVM_CPUID_BIT_AVX512_4VNNIW 2
> +#define KVM_CPUID_BIT_AVX512_4FMAPS 3
> +#define KVM_CPUID_BIT_SPEC_CTRL 26
> +#define KVM_CPUID_BIT_STIBP 27
> +
> +/* CPUID[eax=0x80000008].ebx */
> +#define KVM_CPUID_BIT_IBPB_SUPPORT 12
> +
> +static inline bool cpu_has_spec_ctrl(void)
> +{
> + u32 eax, ebx, ecx, edx;
> + cpuid_count(7, 0, &eax, &ebx, &ecx, &edx);
> +
> + return edx & bit(KVM_CPUID_BIT_SPEC_CTRL);
> +}
> +
> +static inline bool cpu_has_ibpb_support(void)
> +{
> + return cpuid_ebx(0x80000008) & bit(KVM_CPUID_BIT_IBPB_SUPPORT);
> +}
> +
> static inline bool supports_cpuid_fault(struct kvm_vcpu *vcpu)
> {
> return vcpu->arch.msr_platform_info & MSR_PLATFORM_INFO_CPUID_FAULT;
>

Reviewed-by: David Hildenbrand <david@redhat.com>

--

Thanks,

David / dhildenb

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