Re: [RFC][PATCH] KVM: SVM: Sync g_pat with guest-written PAT value

["Radim Krčmář" <rkrcmar@redhat.com>]

2015-04-13 08:58+0200, Jan Kiszka:
> When hardware supports the g_pat VMCB field, we can use it for emulating
> the PAT configuration that the guest configures by writing to the
> corresponding MSR.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
> 
> RFC because it is only compile-tested.
> 
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> @@ -3245,6 +3245,15 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
>  	case MSR_VM_IGNNE:
>  		vcpu_unimpl(vcpu, "unimplemented wrmsr: 0x%x data 0x%llx\n", ecx, data);
>  		break;
> +	case MSR_IA32_CR_PAT:
> +		if (npt_enabled) {
> +			if (!kvm_mtrr_valid(vcpu, MSR_IA32_CR_PAT, data))
> +				return 1;
> +			svm->vmcb->save.g_pat = data;
> +			vcpu->arch.pat = data;

Disregarding my Reviewed-by, the code is missing:

  mark_dirty(svm->vmcb, VMCB_NPT);

Also,

Tested-by: Radim Krčmář <rkrcmar@redhat.com>