linux-kernel - [PATCH 4.14 02/38] KVM: x86: determine if an exception has an error code only when injecting it.

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Date:   Mon,  2 Aug 2021 15:44:24 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Maxim Levitsky <mlevitsk@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Zubin Mithra <zsm@...omium.org>
Subject: [PATCH 4.14 02/38] KVM: x86: determine if an exception has an error code only when injecting it.

From: Maxim Levitsky <mlevitsk@...hat.com>

commit b97f074583736c42fb36f2da1164e28c73758912 upstream.

A page fault can be queued while vCPU is in real paged mode on AMD, and
AMD manual asks the user to always intercept it
(otherwise result is undefined).
The resulting VM exit, does have an error code.

Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
Message-Id: <20210225154135.405125-2-mlevitsk@...hat.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Zubin Mithra <zsm@...omium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/kvm/x86.c |   13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -400,8 +400,6 @@ static void kvm_multiple_exception(struc
 
 	if (!vcpu->arch.exception.pending && !vcpu->arch.exception.injected) {
 	queue:
-		if (has_error && !is_protmode(vcpu))
-			has_error = false;
 		if (reinject) {
 			/*
 			 * On vmentry, vcpu->arch.exception.pending is only
@@ -6624,13 +6622,20 @@ static void update_cr8_intercept(struct
 	kvm_x86_ops->update_cr8_intercept(vcpu, tpr, max_irr);
 }
 
+static void kvm_inject_exception(struct kvm_vcpu *vcpu)
+{
+       if (vcpu->arch.exception.error_code && !is_protmode(vcpu))
+               vcpu->arch.exception.error_code = false;
+       kvm_x86_ops->queue_exception(vcpu);
+}
+
 static int inject_pending_event(struct kvm_vcpu *vcpu)
 {
 	int r;
 
 	/* try to reinject previous events if any */
 	if (vcpu->arch.exception.injected) {
-		kvm_x86_ops->queue_exception(vcpu);
+		kvm_inject_exception(vcpu);
 		return 0;
 	}
 
@@ -6675,7 +6680,7 @@ static int inject_pending_event(struct k
 			kvm_update_dr7(vcpu);
 		}
 
-		kvm_x86_ops->queue_exception(vcpu);
+		kvm_inject_exception(vcpu);
 	} else if (vcpu->arch.smi_pending && !is_smm(vcpu)) {
 		vcpu->arch.smi_pending = false;
 		enter_smm(vcpu);