1 files changed, 32 insertions, 5 deletions

diff --git a/arch/x86/kvm/irq_comm.c b/arch/x86/kvm/irq_comm.c
index 8136695f7b96..d6d792b5d1bd 100644
--- a/arch/x86/kvm/irq_comm.c
+++ b/arch/x86/kvm/irq_comm.c
@@ -402,6 +402,33 @@ void kvm_arch_post_irq_routing_update(struct kvm *kvm)
 	kvm_make_scan_ioapic_request(kvm);
 }
 
+void kvm_scan_ioapic_irq(struct kvm_vcpu *vcpu, u32 dest_id, u16 dest_mode,
+			 u8 vector, unsigned long *ioapic_handled_vectors)
+{
+	/*
+	 * Intercept EOI if the vCPU is the target of the new IRQ routing, or
+	 * the vCPU has a pending IRQ from the old routing, i.e. if the vCPU
+	 * may receive a level-triggered IRQ in the future, or already received
+	 * level-triggered IRQ.  The EOI needs to be intercepted and forwarded
+	 * to I/O APIC emulation so that the IRQ can be de-asserted.
+	 */
+	if (kvm_apic_match_dest(vcpu, NULL, APIC_DEST_NOSHORT, dest_id, dest_mode)) {
+		__set_bit(vector, ioapic_handled_vectors);
+	} else if (kvm_apic_pending_eoi(vcpu, vector)) {
+		__set_bit(vector, ioapic_handled_vectors);
+
+		/*
+		 * Track the highest pending EOI for which the vCPU is NOT the
+		 * target in the new routing.  Only the EOI for the IRQ that is
+		 * in-flight (for the old routing) needs to be intercepted, any
+		 * future IRQs that arrive on this vCPU will be coincidental to
+		 * the level-triggered routing and don't need to be intercepted.
+		 */
+		if ((int)vector > vcpu->arch.highest_stale_pending_ioapic_eoi)
+			vcpu->arch.highest_stale_pending_ioapic_eoi = vector;
+	}
+}
+
 void kvm_scan_ioapic_routes(struct kvm_vcpu *vcpu,
 			    ulong *ioapic_handled_vectors)
 {
@@ -424,11 +451,11 @@ void kvm_scan_ioapic_routes(struct kvm_vcpu *vcpu,
 
 			kvm_set_msi_irq(vcpu->kvm, entry, &irq);
 
-			if (irq.trig_mode &&
-			    (kvm_apic_match_dest(vcpu, NULL, APIC_DEST_NOSHORT,
-						 irq.dest_id, irq.dest_mode) ||
-			     kvm_apic_pending_eoi(vcpu, irq.vector)))
-				__set_bit(irq.vector, ioapic_handled_vectors);
+			if (!irq.trig_mode)
+				continue;
+
+			kvm_scan_ioapic_irq(vcpu, irq.dest_id, irq.dest_mode,
+					    irq.vector, ioapic_handled_vectors);
 		}
 	}
 	srcu_read_unlock(&kvm->irq_srcu, idx);