linux-kernel - Re: [PATCH v5 3/4] KVM: async_pf: Force a nested vmexit if the injected #PF is async

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Date:   Tue, 27 Jun 2017 15:40:41 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Wanpeng Li <kernellwp@...il.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     Radim Krčmář <rkrcmar@...hat.com>,
        Wanpeng Li <wanpeng.li@...mail.com>
Subject: Re: [PATCH v5 3/4] KVM: async_pf: Force a nested vmexit if the
 injected #PF is async_pf



On 27/06/2017 03:47, Wanpeng Li wrote:
> -static int nested_vmx_check_exception(struct kvm_vcpu *vcpu, unsigned nr)
> +static int nested_vmx_check_exception(struct kvm_vcpu *vcpu)
>  {
>  	struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
> +	unsigned int nr = vcpu->arch.exception.nr;
>  
> -	if (!(vmcs12->exception_bitmap & (1u << nr)))
> +	if (!((vmcs12->exception_bitmap & (1u << nr)) ||
> +		(nr == PF_VECTOR && vcpu->arch.exception.async_page_fault)))
>  		return 0;
>  
> +	if (vcpu->arch.exception.async_page_fault) {
> +		vmcs_write32(VM_EXIT_INTR_ERROR_CODE, vcpu->arch.exception.error_code);
> +		nested_vmx_vmexit(vcpu, EXIT_REASON_EXCEPTION_NMI,
> +			PF_VECTOR | INTR_TYPE_HARD_EXCEPTION |
> +			INTR_INFO_DELIVER_CODE_MASK | INTR_INFO_VALID_MASK,
> +			vcpu->arch.apf.nested_apf_token);
> +		return 1;
> +	}
> +
>  	nested_vmx_vmexit(vcpu, EXIT_REASON_EXCEPTION_NMI,
>  			  vmcs_read32(VM_EXIT_INTR_INFO),
>  			  vmcs_readl(EXIT_QUALIFICATION));
> @@ -2442,7 +2453,7 @@ static void vmx_queue_exception(struct kvm_vcpu *vcpu)
>  	u32 intr_info = nr | INTR_INFO_VALID_MASK;
>  
>  	if (!reinject && is_guest_mode(vcpu) &&
> -	    nested_vmx_check_exception(vcpu, nr))
> +	    nested_vmx_check_exception(vcpu))
>  		return;
>  
>  	if (has_error_code) {

The corresponding change for svm.c should be:

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 6e3095d1bad4..b92f56b98844 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2391,15 +2391,19 @@ static int nested_svm_check_exception(struct vcpu_svm *svm, unsigned nr,
 	if (!is_guest_mode(&svm->vcpu))
 		return 0;
 
+	vmexit = nested_svm_intercept(svm);
+	if (vmexit != NESTED_EXIT_DONE)
+		return 0;
+
 	svm->vmcb->control.exit_code = SVM_EXIT_EXCP_BASE + nr;
 	svm->vmcb->control.exit_code_hi = 0;
 	svm->vmcb->control.exit_info_1 = error_code;
-	svm->vmcb->control.exit_info_2 = svm->vcpu.arch.cr2;
-
-	vmexit = nested_svm_intercept(svm);
-	if (vmexit == NESTED_EXIT_DONE)
-		svm->nested.exit_required = true;
+	if (svm->vcpu.arch.exception.nested_apf)
+		svm->vmcb->control.exit_info_2 = svm->vcpu.arch.apf.nested_apf_token;
+	else
+		svm->vmcb->control.exit_info_2 = svm->vcpu.arch.cr2;
 
+	svm->nested.exit_required = true;
 	return vmexit;
 }
 
@@ -2592,7 +2596,7 @@ static int nested_svm_intercept(struct vcpu_svm *svm)
 			vmexit = NESTED_EXIT_DONE;
 		/* async page fault always cause vmexit */
 		else if ((exit_code == SVM_EXIT_EXCP_BASE + PF_VECTOR) &&
-			 svm->apf_reason != 0)
+			 svm->vcpu.arch.exception.nested_apf)
 			vmexit = NESTED_EXIT_DONE;
 		break;
 	}

(where I'm already using the "nested_apf" name I proposed in the other email.

Paolo