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SubjectRe: [PATCH v5 3/3] KVM: x86: Enable Intel MPX for guest
Il 24/02/2014 11:58, Liu, Jinsong ha scritto:
> @@ -599,6 +599,9 @@ int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
> u64 old_xcr0 = vcpu->arch.xcr0;
> u64 valid_bits;
>
> + if (!kvm_x86_ops->mpx_supported || !kvm_x86_ops->mpx_supported())
> + xcr0 &= ~(XSTATE_BNDREGS | XSTATE_BNDCSR);
> +
> /* Only support XCR_XFEATURE_ENABLED_MASK(xcr0) now */
> if (index != XCR_XFEATURE_ENABLED_MASK)
> return 1;

This hunk is incorrect, and I can simply drop it when applying. If MPX
is not supported, it should not be in the 0Dh CPUID leaf and thus in
vcpu->arch.guest_supported_xcr0.

This however relies on userspace passing a "sensible" value of CPUID.
I'll send a patch to strengthen the computation of guest_supported_xcr0.

Thanks!

Paolo


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