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    Subject[PATCH 2/2] KVM: SVM: Add support for VMCB address check change
    Date
    New AMD CPUs have a change that checks VMEXIT intercept on special SVM
    instructions before checking their EAX against reserved memory region.
    This change is indicated by CPUID_0x8000000A_EDX[28]. If it is 1, KVM
    doesn't need to intercept and emulate #GP faults for such instructions
    because #GP isn't supposed to be triggered.

    Co-developed-by: Bandan Das <bsd@redhat.com>
    Signed-off-by: Bandan Das <bsd@redhat.com>
    Signed-off-by: Wei Huang <wei.huang2@amd.com>
    ---
    arch/x86/include/asm/cpufeatures.h | 1 +
    arch/x86/kvm/svm/svm.c | 2 +-
    2 files changed, 2 insertions(+), 1 deletion(-)

    diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
    index 84b887825f12..ea89d6fdd79a 100644
    --- a/arch/x86/include/asm/cpufeatures.h
    +++ b/arch/x86/include/asm/cpufeatures.h
    @@ -337,6 +337,7 @@
    #define X86_FEATURE_AVIC (15*32+13) /* Virtual Interrupt Controller */
    #define X86_FEATURE_V_VMSAVE_VMLOAD (15*32+15) /* Virtual VMSAVE VMLOAD */
    #define X86_FEATURE_VGIF (15*32+16) /* Virtual GIF */
    +#define X86_FEATURE_SVME_ADDR_CHK (15*32+28) /* "" SVME addr check */

    /* Intel-defined CPU features, CPUID level 0x00000007:0 (ECX), word 16 */
    #define X86_FEATURE_AVX512VBMI (16*32+ 1) /* AVX512 Vector Bit Manipulation instructions*/
    diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
    index 74620d32aa82..451b82df2eab 100644
    --- a/arch/x86/kvm/svm/svm.c
    +++ b/arch/x86/kvm/svm/svm.c
    @@ -311,7 +311,7 @@ int svm_set_efer(struct kvm_vcpu *vcpu, u64 efer)
    svm->vmcb->save.efer = efer | EFER_SVME;
    vmcb_mark_dirty(svm->vmcb, VMCB_CR);
    /* Enable GP interception for SVM instructions if needed */
    - if (efer & EFER_SVME)
    + if ((efer & EFER_SVME) && !boot_cpu_has(X86_FEATURE_SVME_ADDR_CHK))
    set_exception_intercept(svm, GP_VECTOR);

    return 0;
    --
    2.27.0
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