linux-kernel - [PATCH] KVM: x86: fix uninitialized variable use on KVM_REQ_TRIPLE

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Message-Id: <20221130161531.891135-1-pbonzini@redhat.com>
Date:   Wed, 30 Nov 2022 11:15:31 -0500
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH] KVM: x86: fix uninitialized variable use on KVM_REQ_TRIPLE_FAULT

If a triple fault was fixed by kvm_x86_ops.nested_ops->triple_fault (by
turning it into a vmexit), there is no need to leave vcpu_enter_guest().
Any vcpu->requests will be caught later before the actual vmentry,
and in fact vcpu_enter_guest() was not initializing the "r" variable.
Depending on the compiler's whims, this could cause the
x86_64/triple_fault_event_test test to fail.

Cc: Maxim Levitsky <mlevitsk@...hat.com>
Fixes: 92e7d5c83aff ("KVM: x86: allow L1 to not intercept triple fault")
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/x86.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 246bdc9a9154..7f850dfb4086 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10280,8 +10280,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 				vcpu->run->exit_reason = KVM_EXIT_SHUTDOWN;
 				vcpu->mmio_needed = 0;
 				r = 0;
+				goto out;
 			}
-			goto out;
 		}
 		if (kvm_check_request(KVM_REQ_APF_HALT, vcpu)) {
 			/* Page is swapped out. Do synthetic halt */
-- 
2.31.1