[PATCH v7 11/26] KVM: nSVM: Clear EVENTINJ fields in vmcb12 on nested #VMEXIT

[Yosry Ahmed]

According to the APM, from the reference of the VMRUN instruction:

	Upon #VMEXIT, the processor performs the following actions in
	order to return to the host execution context:
	...
	clear EVENTINJ field in VMCB

KVM syncs EVENTINJ fields from vmcb02 to cached vmcb12 on every L2->L0
 #VMEXIT. Since these fields are zeroed by the CPU on #VMEXIT, they will
mostly be zeroed in vmcb12 on nested #VMEXIT by nested_svm_vmexit().
However, this is not the case when:
1. Consistency checks fail, as nested_svm_vmexit() is not called.
2. Entering guest mode fails before L2 runs (e.g. due to failed load of
   CR3).

(2) was broken by commit 2d8a42be0e2b ("KVM: nSVM: synchronize VMCB
controls updated by the processor on every vmexit"), as prior to that
nested_svm_vmexit() always zeroed EVENTINJ fields.

Explicitly clear the fields all nested #VMEXIT code paths.

Fixes: 3d6368ef580a ("KVM: SVM: Add VMRUN handler")
Fixes: 2d8a42be0e2b ("KVM: nSVM: synchronize VMCB controls updated by the processor on every vmexit")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Yosry Ahmed <yosry@xxxxxxxxxx>
---
 arch/x86/kvm/svm/nested.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 04ccab887c5ec..f0ed352a3e901 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -1036,6 +1036,8 @@ int nested_svm_vmrun(struct kvm_vcpu *vcpu)
 		vmcb12->control.exit_code    = SVM_EXIT_ERR;
 		vmcb12->control.exit_info_1  = 0;
 		vmcb12->control.exit_info_2  = 0;
+		vmcb12->control.event_inj = 0;
+		vmcb12->control.event_inj_err = 0;
 		svm_set_gif(svm, false);
 		goto out;
 	}
@@ -1179,9 +1181,9 @@ static int nested_svm_vmexit_update_vmcb12(struct kvm_vcpu *vcpu)
 	if (nested_vmcb12_has_lbrv(vcpu))
 		svm_copy_lbrs(&vmcb12->save, &vmcb02->save);
 
+	vmcb12->control.event_inj	  = 0;
+	vmcb12->control.event_inj_err	  = 0;
 	vmcb12->control.int_ctl           = svm->nested.ctl.int_ctl;
-	vmcb12->control.event_inj         = svm->nested.ctl.event_inj;
-	vmcb12->control.event_inj_err     = svm->nested.ctl.event_inj_err;
 
 	trace_kvm_nested_vmexit_inject(vmcb12->control.exit_code,
 				       vmcb12->control.exit_info_1,
-- 
2.53.0.473.g4a7958ca14-goog