[PATCH 4.19 03/17] KVM: x86: determine if an exception has an error code only when injecting it.

Greg Kroah-Hartman
2021-07-29T13:56:50Z

From: Maxim Levitsky <mlevitsk@redhat.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@redhat.com>
Message-Id: <20210225154135.405125-2-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Zubin Mithra <zsm@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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
@@ -416,8 +416,6 @@ 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
@@ -7114,6 +7112,13 @@ 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;
@@ -7121,7 +7126,7 @@ static int inject_pending_event(struct k
/* try to reinject previous events if any */

if (vcpu->arch.exception.injected)
- kvm_x86_ops->queue_exception(vcpu);
+ kvm_inject_exception(vcpu);
/*
* Do not inject an NMI or interrupt if there is a pending
* exception. Exceptions and interrupts are recognized at
@@ -7175,7 +7180,7 @@ static int inject_pending_event(struct k
kvm_update_dr7(vcpu);
}

- kvm_x86_ops->queue_exception(vcpu);
+ kvm_inject_exception(vcpu);
}

/* Don't consider new event if we re-injected an event */