[PATCH v8 1/6] kvm: Allow filtering of acked irqs

[Alex Williamson <alex.williamson@redhat.com>]

Registering an kvm_irq_ack_notifier with kian.irq_source_id < 0
retains existing behavior, filling in the actual irq_source_id results
in the callback only being called when the specified irq_source_id is
asserting the given gsi.

The i8254 PIT remains unfiltered because it de-asserts it's irq source
id, so it's notifier would never get called otherwise.  KVM device
assignment gets filtering as it de-asserts the GSI in it's notifier.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---

 arch/x86/kvm/i8254.c     |    1 +
 arch/x86/kvm/i8259.c     |    8 +++++++-
 include/linux/kvm_host.h |    4 +++-
 virt/kvm/assigned-dev.c  |    1 +
 virt/kvm/ioapic.c        |    5 ++++-
 virt/kvm/irq_comm.c      |    6 ++++--
 6 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index adba28f..2355d19 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -709,6 +709,7 @@ struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags)
 	hrtimer_init(&pit_state->pit_timer.timer,
 		     CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
 	pit_state->irq_ack_notifier.gsi = 0;
+	pit_state->irq_ack_notifier.irq_source_id = -1; /* No filter */
 	pit_state->irq_ack_notifier.irq_acked = kvm_pit_ack_irq;
 	kvm_register_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier);
 	pit_state->pit_timer.reinject = true;
diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
index e498b18..d2175a9 100644
--- a/arch/x86/kvm/i8259.c
+++ b/arch/x86/kvm/i8259.c
@@ -74,9 +74,14 @@ static void pic_unlock(struct kvm_pic *s)
 
 static void pic_clear_isr(struct kvm_kpic_state *s, int irq)
 {
+	unsigned long irq_source_ids;
+
 	s->isr &= ~(1 << irq);
 	if (s != &s->pics_state->pics[0])
 		irq += 8;
+
+	irq_source_ids = s->pics_state->irq_states[irq];
+
 	/*
 	 * We are dropping lock while calling ack notifiers since ack
 	 * notifier callbacks for assigned devices call into PIC recursively.
@@ -84,7 +89,8 @@ static void pic_clear_isr(struct kvm_kpic_state *s, int irq)
 	 * it should be safe since PIC state is already updated at this stage.
 	 */
 	pic_unlock(s->pics_state);
-	kvm_notify_acked_irq(s->pics_state->kvm, SELECT_PIC(irq), irq);
+	kvm_notify_acked_irq(s->pics_state->kvm, SELECT_PIC(irq), irq,
+			     irq_source_ids);
 	pic_lock(s->pics_state);
 }
 
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index b70b48b..2ad3e4a 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -577,6 +577,7 @@ int kvm_is_mmio_pfn(pfn_t pfn);
 
 struct kvm_irq_ack_notifier {
 	struct hlist_node link;
+	int irq_source_id;
 	unsigned gsi;
 	void (*irq_acked)(struct kvm_irq_ack_notifier *kian);
 };
@@ -627,7 +628,8 @@ void kvm_get_intr_delivery_bitmask(struct kvm_ioapic *ioapic,
 int kvm_set_irq(struct kvm *kvm, int irq_source_id, u32 irq, int level);
 int kvm_set_msi(struct kvm_kernel_irq_routing_entry *irq_entry, struct kvm *kvm,
 		int irq_source_id, int level);
-void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin);
+void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin,
+			  unsigned long irq_source_ids);
 void kvm_register_irq_ack_notifier(struct kvm *kvm,
 				   struct kvm_irq_ack_notifier *kian);
 void kvm_unregister_irq_ack_notifier(struct kvm *kvm,
diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c
index 23a41a9..a08c9c1 100644
--- a/virt/kvm/assigned-dev.c
+++ b/virt/kvm/assigned-dev.c
@@ -407,6 +407,7 @@ static int assigned_device_enable_guest_intx(struct kvm *kvm,
 {
 	dev->guest_irq = irq->guest_irq;
 	dev->ack_notifier.gsi = irq->guest_irq;
+	dev->ack_notifier.irq_source_id = dev->irq_source_id;
 	return 0;
 }
 
diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
index ef61d52..1a9f445 100644
--- a/virt/kvm/ioapic.c
+++ b/virt/kvm/ioapic.c
@@ -241,10 +241,12 @@ static void __kvm_ioapic_update_eoi(struct kvm_ioapic *ioapic, int vector,
 
 	for (i = 0; i < IOAPIC_NUM_PINS; i++) {
 		union kvm_ioapic_redirect_entry *ent = &ioapic->redirtbl[i];
+		unsigned long irq_source_ids;
 
 		if (ent->fields.vector != vector)
 			continue;
 
+		irq_source_ids = ioapic->irq_states[i];
 		/*
 		 * We are dropping lock while calling ack notifiers because ack
 		 * notifier callbacks for assigned devices call into IOAPIC
@@ -254,7 +256,8 @@ static void __kvm_ioapic_update_eoi(struct kvm_ioapic *ioapic, int vector,
 		 * after ack notifier returns.
 		 */
 		spin_unlock(&ioapic->lock);
-		kvm_notify_acked_irq(ioapic->kvm, KVM_IRQCHIP_IOAPIC, i);
+		kvm_notify_acked_irq(ioapic->kvm, KVM_IRQCHIP_IOAPIC, i,
+				     irq_source_ids);
 		spin_lock(&ioapic->lock);
 
 		if (trigger_mode != IOAPIC_LEVEL_TRIG)
diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index 83402d7..7d75126 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -173,7 +173,8 @@ int kvm_set_irq(struct kvm *kvm, int irq_source_id, u32 irq, int level)
 	return ret;
 }
 
-void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
+void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin,
+			  unsigned long irq_source_ids)
 {
 	struct kvm_irq_ack_notifier *kian;
 	struct hlist_node *n;
@@ -186,7 +187,8 @@ void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
 	if (gsi != -1)
 		hlist_for_each_entry_rcu(kian, n, &kvm->irq_ack_notifier_list,
 					 link)
-			if (kian->gsi == gsi)
+			if (kian->gsi == gsi && (kian->irq_source_id < 0 ||
+			    test_bit(kian->irq_source_id, &irq_source_ids)))
 				kian->irq_acked(kian);
 	rcu_read_unlock();
 }