[10/11] Change irq routing table to use gsi indexed array.

Commit Message

Gleb Natapov July 16, 2009, 2:03 p.m. UTC

Use gsi indexed array instead of scanning all entries on each interrupt
injection. Also maintain back mapping from irqchip/pin to gsi to speedup
interrupt acknowledgment notifications.

Signed-off-by: Gleb Natapov <[e-mail]>
---
 include/linux/kvm_host.h |   11 +++++++-
 virt/kvm/irq_comm.c      |   57 +++++++++++++++++++++++++++++----------------
 2 files changed, 46 insertions(+), 22 deletions(-)

Patch

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 6bcc79f..2715e59 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -128,7 +128,14 @@  struct kvm_kernel_irq_routing_entry {
 		} irqchip;
 		struct msi_msg msi;
 	};
-	struct list_head link;
+	struct hlist_node link;
+};
+
+struct kvm_irq_routing_table {
+	int chip[3][KVM_IOAPIC_NUM_PINS];
+	struct kvm_kernel_irq_routing_entry *rt_entries;
+	u32 max_gsi;
+	struct hlist_head map[0];
 };
 
 struct kvm {
@@ -165,7 +172,7 @@  struct kvm {
 #endif
 
 #ifdef CONFIG_HAVE_KVM_IRQCHIP
-	struct kvm_kernel_irq_routing_entry *irq_routing;
+	struct kvm_irq_routing_table *irq_routing;
 	spinlock_t irq_routing_lock;
 	struct hlist_head mask_notifier_list;
 	struct hlist_head irq_ack_notifier_list;
diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index be30124..ae11114 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -128,6 +128,8 @@  static int __kvm_set_irq(struct kvm *kvm, int irq_source_id, int irq, int level,
 	struct kvm_kernel_irq_routing_entry *e;
 	unsigned long *irq_state, sig_level;
 	int ret = -1;
+	struct kvm_irq_routing_table *irq_rt;
+	struct hlist_node *n;
 
 	trace_kvm_set_irq(irq, level, irq_source_id);
 
@@ -150,15 +152,15 @@  static int __kvm_set_irq(struct kvm *kvm, int irq_source_id, int irq, int level,
 	 * writes to the unused one.
 	 */
 	rcu_read_lock();
-	for (e = rcu_dereference(kvm->irq_routing); e && e->set; e++) {
-		if (e->gsi == irq) {
+	irq_rt = rcu_dereference(kvm->irq_routing);
+	if (irq < irq_rt->max_gsi)
+		hlist_for_each_entry(e, n, &irq_rt->map[irq], link) {
 			int r = e->set(e, kvm, sig_level, notifier);
 			if (r < 0)
 				continue;
 
 			ret = r + ((ret < 0) ? 0 : ret);
 		}
-	}
 	rcu_read_unlock();
 	return ret;
 }
@@ -175,21 +177,16 @@  int kvm_notifier_set_irq(struct kvm *kvm, int irq_source_id, int irq, int level)
 
 void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
 {
-	struct kvm_kernel_irq_routing_entry *e;
 	struct kvm_irq_ack_notifier *kian;
 	struct hlist_node *n;
-	unsigned gsi = pin;
+	unsigned gsi;
 
 	trace_kvm_ack_irq(irqchip, pin);
 
 	rcu_read_lock();
-	for (e = rcu_dereference(kvm->irq_routing); e && e->set; e++) {
-		if (e->irqchip.irqchip == irqchip &&
-		    e->irqchip.pin == pin) {
-			gsi = e->gsi;
-			break;
-		}
-	}
+	gsi = rcu_dereference(kvm->irq_routing)->chip[irqchip][pin];
+	if (gsi == -1)
+		gsi = pin;
 
 	hlist_for_each_entry_rcu(kian, n, &kvm->irq_ack_notifier_list, link)
 		if (kian->gsi == gsi)
@@ -290,7 +287,8 @@  void kvm_free_irq_routing(struct kvm *kvm)
 	kfree(kvm->irq_routing);
 }
 
-static int setup_routing_entry(struct kvm_kernel_irq_routing_entry *e,
+static int setup_routing_entry(struct kvm_irq_routing_table *rt,
+			       struct kvm_kernel_irq_routing_entry *e,
 			       const struct kvm_irq_routing_entry *ue)
 {
 	int r = -EINVAL;
@@ -316,6 +314,9 @@  static int setup_routing_entry(struct kvm_kernel_irq_routing_entry *e,
 		}
 		e->irqchip.irqchip = ue->u.irqchip.irqchip;
 		e->irqchip.pin = ue->u.irqchip.pin + delta;
+		if (e->irqchip.pin > KVM_IOAPIC_NUM_PINS)
+			goto out;
+		rt->chip[ue->u.irqchip.irqchip][e->irqchip.pin] = ue->gsi;
 		break;
 	case KVM_IRQ_ROUTING_MSI:
 		e->set = kvm_set_msi;
@@ -326,6 +327,8 @@  static int setup_routing_entry(struct kvm_kernel_irq_routing_entry *e,
 	default:
 		goto out;
 	}
+
+	hlist_add_head(&e->link, &rt->map[e->gsi]);
 	r = 0;
 out:
 	return r;
@@ -337,23 +340,37 @@  int kvm_set_irq_routing(struct kvm *kvm,
 			unsigned nr,
 			unsigned flags)
 {
-	struct kvm_kernel_irq_routing_entry *new, *old;
-	unsigned i;
+	struct kvm_irq_routing_table *new, *old;
+	u32 i, j, max_gsi = 0;
 	int r;
 
-	/* last elemet is left zeored and indicates the end of the array */
-	new = kzalloc(sizeof(*new) * (nr + 1), GFP_KERNEL);
+	for (i = 0; i < nr; ++i) {
+		if (ue[i].gsi >= KVM_MAX_IRQ_ROUTES)
+			return -EINVAL;
+		max_gsi = max(max_gsi, ue[i].gsi);
+	}
+
+	max_gsi += 1;
+
+	new = kzalloc(sizeof(*new) + (max_gsi * sizeof(struct hlist_head)) +
+		      (nr * sizeof(struct kvm_kernel_irq_routing_entry)),
+		      GFP_KERNEL);
 
 	if (!new)
 		return -ENOMEM;
 
+	new->rt_entries = (void *)&new->map[max_gsi];
+
+	new->max_gsi = max_gsi;
+	for (i = 0; i < 3; i++)
+		for (j = 0; j < KVM_IOAPIC_NUM_PINS; j++)
+			new->chip[i][j] = -1;
+
 	for (i = 0; i < nr; ++i) {
 		r = -EINVAL;
-		if (ue->gsi >= KVM_MAX_IRQ_ROUTES)
-			goto out;
 		if (ue->flags)
 			goto out;
-		r = setup_routing_entry(new + i, ue);
+		r = setup_routing_entry(new, &new->rt_entries[i], ue);
 		if (r)
 			goto out;
 		++ue;