KVM: arm/arm64: Fix emulated ptimer irq injection

The emulated ptimer needs to track the level changes, otherwise the the interrupt will never get deasserted, resulting in the guest getting stuck in an interrupt storm if it enables ptimer interrupts. This was found with kvm-unit-tests; the ptimer tests hung as soon as interrupts were enabled. Typical Linux guests don't have a problem as they prefer using the virtual timer. Fixes: bee038a ("KVM: arm/arm64: Rework the timer code to use a timer_map") Signed-off-by: Andrew Jones <[email protected]> [Simplified the patch to res we only care about emulated timers here] Signed-off-by: Marc Zyngier <[email protected]>
vieko · Jun 19, 2019 · e4e5a86 · e4e5a86
1 parent 4729ec8
commit e4e5a86
Showing 1 changed file with 3 additions and 2 deletions.
diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
@@ -321,14 +321,15 @@ static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level,
 	}
 }
 
+/* Only called for a fully emulated timer */
 static void timer_emulate(struct arch_timer_context *ctx)
 {
 	bool should_fire = kvm_timer_should_fire(ctx);
 
 	trace_kvm_timer_emulate(ctx, should_fire);
 
-	if (should_fire) {
-		kvm_timer_update_irq(ctx->vcpu, true, ctx);
+	if (should_fire != ctx->irq.level) {
+		kvm_timer_update_irq(ctx->vcpu, should_fire, ctx);
 		return;
 	}