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    Subject[PATCH 1/8] KVM: x86: add SPEC_CTRL and IBPB_SUPPORT accessors
    Date
    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;
    --
    1.8.3.1

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