Commit bf672720 authored by Maxim Levitsky's avatar Maxim Levitsky Committed by Paolo Bonzini
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KVM: x86: check the kvm_cpu_get_interrupt result before using it 



The code was blindly assuming that kvm_cpu_get_interrupt never returns -1
when there is a pending interrupt.

While this should be true, a bug in KVM can still cause this.

If -1 is returned, the code before this patch was converting it to 0xFF,
and 0xFF interrupt was injected to the guest, which results in an issue
which was hard to debug.

Add WARN_ON_ONCE to catch this case and	skip the injection
if this happens again.

Signed-off-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20230726135945.260841-4-mlevitsk@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent cff540eb

arch/x86/kvm/x86.c

+7 −3
Original line number Diff line number Diff line
@@ -10203,10 +10203,14 @@ static int kvm_check_and_inject_events(struct kvm_vcpu *vcpu, 
		if (r < 0)

			goto out;

		if (r) {

			kvm_queue_interrupt(vcpu, kvm_cpu_get_interrupt(vcpu), false);

			int irq = kvm_cpu_get_interrupt(vcpu);



			if (!WARN_ON_ONCE(irq == -1)) {

				kvm_queue_interrupt(vcpu, irq, false);

				static_call(kvm_x86_inject_irq)(vcpu, false);

				WARN_ON(static_call(kvm_x86_interrupt_allowed)(vcpu, true) < 0);

			}

		}

		if (kvm_cpu_has_injectable_intr(vcpu))

			static_call(kvm_x86_enable_irq_window)(vcpu);

	}