1 files changed, 19 insertions, 6 deletions

diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
index d4b6015..2458a1d 100644
--- a/virt/kvm/ioapic.c
+++ b/virt/kvm/ioapic.c
@@ -97,6 +97,14 @@ static void rtc_irq_eoi_tracking_reset(struct kvm_ioapic *ioapic)
 	bitmap_zero(ioapic->rtc_status.dest_map, KVM_MAX_VCPUS);
 }
 
+static void kvm_rtc_eoi_tracking_restore_all(struct kvm_ioapic *ioapic);
+
+static void rtc_status_pending_eoi_check_valid(struct kvm_ioapic *ioapic)
+{
+	if (WARN_ON(ioapic->rtc_status.pending_eoi < 0))
+		kvm_rtc_eoi_tracking_restore_all(ioapic);
+}
+
 static void __rtc_irq_eoi_tracking_restore_one(struct kvm_vcpu *vcpu)
 {
 	bool new_val, old_val;
@@ -120,9 +128,8 @@ static void __rtc_irq_eoi_tracking_restore_one(struct kvm_vcpu *vcpu)
 	} else {
 		__clear_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map);
 		ioapic->rtc_status.pending_eoi--;
+		rtc_status_pending_eoi_check_valid(ioapic);
 	}
-
-	WARN_ON(ioapic->rtc_status.pending_eoi < 0);
 }
 
 void kvm_rtc_eoi_tracking_restore_one(struct kvm_vcpu *vcpu)
@@ -149,10 +156,10 @@ static void kvm_rtc_eoi_tracking_restore_all(struct kvm_ioapic *ioapic)
 
 static void rtc_irq_eoi(struct kvm_ioapic *ioapic, struct kvm_vcpu *vcpu)
 {
-	if (test_and_clear_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map))
+	if (test_and_clear_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map)) {
 		--ioapic->rtc_status.pending_eoi;
-
-	WARN_ON(ioapic->rtc_status.pending_eoi < 0);
+		rtc_status_pending_eoi_check_valid(ioapic);
+	}
 }
 
 static bool rtc_irq_check_coalesced(struct kvm_ioapic *ioapic)
@@ -353,10 +360,16 @@ static int ioapic_service(struct kvm_ioapic *ioapic, int irq, bool line_status)
 		ioapic->irr &= ~(1 << irq);
 
 	if (irq == RTC_GSI && line_status) {
+		/*
+		 * pending_eoi cannot ever become negative (see
+		 * rtc_status_pending_eoi_check_valid) and the caller
+		 * ensures that it is only called if it is >= zero, namely
+		 * if rtc_irq_check_coalesced returns false).
+		 */
 		BUG_ON(ioapic->rtc_status.pending_eoi != 0);
 		ret = kvm_irq_delivery_to_apic(ioapic->kvm, NULL, &irqe,
 				ioapic->rtc_status.dest_map);
-		ioapic->rtc_status.pending_eoi = ret;
+		ioapic->rtc_status.pending_eoi = (ret < 0 ? 0 : ret);
 	} else
 		ret = kvm_irq_delivery_to_apic(ioapic->kvm, NULL, &irqe, NULL);