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    SubjectRe: [PATCH v2 15/15] KVM: x86/cpuid: Advertise Arch LBR feature in CPUID
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    On 25/11/2022 12:06 pm, Yang Weijiang wrote:
    > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
    > index 85e3df6217af..60b3c591d462 100644
    > --- a/arch/x86/kvm/cpuid.c
    > +++ b/arch/x86/kvm/cpuid.c
    > @@ -134,6 +134,19 @@ static int kvm_check_cpuid(struct kvm_vcpu *vcpu,
    > if (vaddr_bits != 48 && vaddr_bits != 57 && vaddr_bits != 0)
    > return -EINVAL;
    > }
    > + if (kvm_cpu_cap_has(X86_FEATURE_ARCH_LBR)) {
    > + best = cpuid_entry2_find(entries, nent, 0x1c, 0);
    > + if (best) {
    > + unsigned int eax, ebx, ecx, edx;
    > +
    > + /* Reject user-space CPUID if depth is different from host's.*/

    Try to verify this in the KVM selftest, as this behavior is different from the host.

    > + cpuid_count(0x1c, 0, &eax, &ebx, &ecx, &edx); > +
    > + if ((eax & 0xff) &&
    > + (best->eax & 0xff) != BIT(fls(eax & 0xff) - 1))
    > + return -EINVAL;
    > + }
    > + }

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