Re: [PATCH] KVM: x86: Check the right feature bit for MSR_KVM_ASYNC_PF_ACK access

From: Maxim Levitsky
Date: Thu Jul 22 2021 - 08:39:55 EST


On Thu, 2021-07-22 at 14:30 +0200, Vitaly Kuznetsov wrote:
> MSR_KVM_ASYNC_PF_ACK MSR is part of interrupt based asynchronous page fault
> interface and not the original (deprecated) KVM_FEATURE_ASYNC_PF. This is
> stated in Documentation/virt/kvm/msr.rst.
>
> Fixes: 66570e966dd9 ("kvm: x86: only provide PV features if enabled in guest's CPUID")
> Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> ---
> arch/x86/kvm/x86.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index d715ae9f9108..88ff7a1af198 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3406,7 +3406,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> return 1;
> break;
> case MSR_KVM_ASYNC_PF_ACK:
> - if (!guest_pv_has(vcpu, KVM_FEATURE_ASYNC_PF))
> + if (!guest_pv_has(vcpu, KVM_FEATURE_ASYNC_PF_INT))
> return 1;
> if (data & 0x1) {
> vcpu->arch.apf.pageready_pending = false;
> @@ -3745,7 +3745,7 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> msr_info->data = vcpu->arch.apf.msr_int_val;
> break;
> case MSR_KVM_ASYNC_PF_ACK:
> - if (!guest_pv_has(vcpu, KVM_FEATURE_ASYNC_PF))
> + if (!guest_pv_has(vcpu, KVM_FEATURE_ASYNC_PF_INT))
> return 1;
>
> msr_info->data = 0;

Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>

Best regards,
Maxim Levitsky