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: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
---
arch/x86/kvm/x86.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a6b9bea62fb8ac..00b87fcf6da4af 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10203,9 +10203,13 @@ 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);
- static_call(kvm_x86_inject_irq)(vcpu, false);
- WARN_ON(static_call(kvm_x86_interrupt_allowed)(vcpu, true) < 0);
+ 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);
--
2.26.3
