KVM: Fix RTC interrupt coalescing tracking

This reverts most of the f1ed0450. After
the commit kvm_apic_set_irq() no longer returns accurate information
about interrupt injection status if injection is done into disabled
APIC. RTC interrupt coalescing tracking relies on the information to be
accurate and cannot recover if it is not.
Signed-off-by: NGleb Natapov <gleb@redhat.com>

arch/x86/kvm/lapic.c

@@ -405,17 +405,17 @@ int kvm_lapic_find_highest_irr(struct kvm_vcpu *vcpu)
 	return highest_irr;
 }
 
-static void __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
-			      int vector, int level, int trig_mode,
-			      unsigned long *dest_map);
+static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
+			     int vector, int level, int trig_mode,
+			     unsigned long *dest_map);
 
-void kvm_apic_set_irq(struct kvm_vcpu *vcpu, struct kvm_lapic_irq *irq,
-		      unsigned long *dest_map)
+int kvm_apic_set_irq(struct kvm_vcpu *vcpu, struct kvm_lapic_irq *irq,
+		unsigned long *dest_map)
 {
 	struct kvm_lapic *apic = vcpu->arch.apic;
 
-	__apic_accept_irq(apic, irq->delivery_mode, irq->vector,
-			  irq->level, irq->trig_mode, dest_map);
+	return __apic_accept_irq(apic, irq->delivery_mode, irq->vector,
+			irq->level, irq->trig_mode, dest_map);
 }
 
 static int pv_eoi_put_user(struct kvm_vcpu *vcpu, u8 val)
@@ -608,8 +608,7 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,
 	*r = -1;
 
 	if (irq->shorthand == APIC_DEST_SELF) {
-		kvm_apic_set_irq(src->vcpu, irq, dest_map);
-		*r = 1;
+		*r = kvm_apic_set_irq(src->vcpu, irq, dest_map);
 		return true;
 	}
 
@@ -654,8 +653,7 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,
 			continue;
 		if (*r < 0)
 			*r = 0;
-		kvm_apic_set_irq(dst[i]->vcpu, irq, dest_map);
-		*r += 1;
+		*r += kvm_apic_set_irq(dst[i]->vcpu, irq, dest_map);
 	}
 
 	ret = true;
@@ -664,11 +662,15 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,
 	return ret;
 }
 
-/* Set an IRQ pending in the lapic. */
-static void __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
-			      int vector, int level, int trig_mode,
-			      unsigned long *dest_map)
+/*
+ * Add a pending IRQ into lapic.
+ * Return 1 if successfully added and 0 if discarded.
+ */
+static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
+			     int vector, int level, int trig_mode,
+			     unsigned long *dest_map)
 {
+	int result = 0;
 	struct kvm_vcpu *vcpu = apic->vcpu;
 
 	switch (delivery_mode) {
@@ -682,10 +684,13 @@ static void __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
 		if (dest_map)
 			__set_bit(vcpu->vcpu_id, dest_map);
 
-		if (kvm_x86_ops->deliver_posted_interrupt)
+		if (kvm_x86_ops->deliver_posted_interrupt) {
+			result = 1;
 			kvm_x86_ops->deliver_posted_interrupt(vcpu, vector);
-		else {
-			if (apic_test_and_set_irr(vector, apic)) {
+		} else {
+			result = !apic_test_and_set_irr(vector, apic);
+
+			if (!result) {
 				if (trig_mode)
 					apic_debug("level trig mode repeatedly "
 						"for vector %d", vector);
@@ -697,7 +702,7 @@ static void __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
 		}
 out:
 		trace_kvm_apic_accept_irq(vcpu->vcpu_id, delivery_mode,
-					  trig_mode, vector, false);
+				trig_mode, vector, !result);
 		break;
 
 	case APIC_DM_REMRD:
@@ -709,12 +714,14 @@ static void __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
 		break;
 
 	case APIC_DM_NMI:
+		result = 1;
 		kvm_inject_nmi(vcpu);
 		kvm_vcpu_kick(vcpu);
 		break;
 
 	case APIC_DM_INIT:
 		if (!trig_mode || level) {
+			result = 1;
 			/* assumes that there are only KVM_APIC_INIT/SIPI */
 			apic->pending_events = (1UL << KVM_APIC_INIT);
 			/* make sure pending_events is visible before sending
@@ -731,6 +738,7 @@ static void __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
 	case APIC_DM_STARTUP:
 		apic_debug("SIPI to vcpu %d vector 0x%02x\n",
 			   vcpu->vcpu_id, vector);
+		result = 1;
 		apic->sipi_vector = vector;
 		/* make sure sipi_vector is visible for the receiver */
 		smp_wmb();
@@ -752,6 +760,7 @@ static void __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
 		       delivery_mode);
 		break;
 	}
+	return result;
 }
 
 int kvm_apic_compare_prio(struct kvm_vcpu *vcpu1, struct kvm_vcpu *vcpu2)
@@ -1461,7 +1470,7 @@ int apic_has_pending_timer(struct kvm_vcpu *vcpu)
 	return 0;
 }
 
-void kvm_apic_local_deliver(struct kvm_lapic *apic, int lvt_type)
+int kvm_apic_local_deliver(struct kvm_lapic *apic, int lvt_type)
 {
 	u32 reg = kvm_apic_get_reg(apic, lvt_type);
 	int vector, mode, trig_mode;
@@ -1470,8 +1479,10 @@ void kvm_apic_local_deliver(struct kvm_lapic *apic, int lvt_type)
 		vector = reg & APIC_VECTOR_MASK;
 		mode = reg & APIC_MODE_MASK;
 		trig_mode = reg & APIC_LVT_LEVEL_TRIGGER;
-		__apic_accept_irq(apic, mode, vector, 1, trig_mode, NULL);
+		return __apic_accept_irq(apic, mode, vector, 1, trig_mode,
+					NULL);
 	}
+	return 0;
 }
 
 void kvm_apic_nmi_wd_deliver(struct kvm_vcpu *vcpu)

arch/x86/kvm/lapic.h

@@ -57,9 +57,9 @@ void kvm_apic_update_tmr(struct kvm_vcpu *vcpu, u32 *tmr);
 void kvm_apic_update_irr(struct kvm_vcpu *vcpu, u32 *pir);
 int kvm_apic_match_physical_addr(struct kvm_lapic *apic, u16 dest);
 int kvm_apic_match_logical_addr(struct kvm_lapic *apic, u8 mda);
-void kvm_apic_set_irq(struct kvm_vcpu *vcpu, struct kvm_lapic_irq *irq,
-		      unsigned long *dest_map);
-void kvm_apic_local_deliver(struct kvm_lapic *apic, int lvt_type);
+int kvm_apic_set_irq(struct kvm_vcpu *vcpu, struct kvm_lapic_irq *irq,
+		unsigned long *dest_map);
+int kvm_apic_local_deliver(struct kvm_lapic *apic, int lvt_type);
 
 bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,
 		struct kvm_lapic_irq *irq, int *r, unsigned long *dest_map);

virt/kvm/irq_comm.c

@@ -91,8 +91,7 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
 		if (!kvm_is_dm_lowest_prio(irq)) {
 			if (r < 0)
 				r = 0;
-			kvm_apic_set_irq(vcpu, irq, dest_map);
-			r++;
+			r += kvm_apic_set_irq(vcpu, irq, dest_map);
 		} else if (kvm_lapic_enabled(vcpu)) {
 			if (!lowest)
 				lowest = vcpu;
@@ -101,10 +100,8 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
 		}
 	}
 
-	if (lowest) {
-		kvm_apic_set_irq(lowest, irq, dest_map);
-		r = 1;
-	}
+	if (lowest)
+		r = kvm_apic_set_irq(lowest, irq, dest_map);
 
 	return r;
 }