linux-kernel - Re: [PATCH 2/5] KVM: SVM: Use kvm_pat_valid() directly instead of kvm_mtrr

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Date:   Wed, 3 May 2023 23:04:16 +0000
From:   "Huang, Kai" <kai.huang@...el.com>
To:     "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "Christopherson,, Sean" <seanjc@...gle.com>
CC:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "guoke@...ontech.com" <guoke@...ontech.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "haiwenyao@...ontech.com" <haiwenyao@...ontech.com>
Subject: Re: [PATCH 2/5] KVM: SVM: Use kvm_pat_valid() directly instead of
 kvm_mtrr_valid()





> for better or worse, KVM doesn't apply the "zap
> SPTEs" logic to guest PAT changes when the VM has a passthrough device
> with non-coherent DMA.

Is it a bug?

> 
> Signed-off-by: Ke Guo <guoke@...ontech.com>
> [sean: massage changelog]
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>  arch/x86/kvm/svm/svm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index eb308c9994f9..db237ccdc957 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -2935,7 +2935,7 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
>  
>  		break;
>  	case MSR_IA32_CR_PAT:
> -		if (!kvm_mtrr_valid(vcpu, MSR_IA32_CR_PAT, data))
> +		if (!kvm_pat_valid(data))
>  			return 1;
>  		vcpu->arch.pat = data;
>  		svm->vmcb01.ptr->save.g_pat = data;

Anyway for this change,

Reviewed-by: Kai Huang <kai.huang@...el.com>