KVM: irqchip: Provide and use accessors for irq routing table

This provides accessor functions for the KVM interrupt mappings, in
order to reduce the amount of code that accesses the fields of the
kvm_irq_routing_table struct, and restrict that code to one file,
virt/kvm/irqchip.c.  The new functions are kvm_irq_map_gsi(), which
maps from a global interrupt number to a set of IRQ routing entries,
and kvm_irq_map_chip_pin, which maps from IRQ chip and pin numbers to
a global interrupt number.

This also moves the update of kvm_irq_routing_table::chip[][]
into irqchip.c, out of the various kvm_set_routing_entry
implementations.  That means that none of the kvm_set_routing_entry
implementations need the kvm_irq_routing_table argument anymore,
so this removes it.

This does not change any locking or data lifetime rules.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Tested-by: Eric Auger <eric.auger@linaro.org>
Tested-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

3 files changed, 49 insertions, 23 deletions

diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index bae593a545c..15fa9488b2d 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -282,20 +282,22 @@ static void irqfd_update(struct kvm *kvm, struct _irqfd *irqfd,
 			 struct kvm_irq_routing_table *irq_rt)
 {
 	struct kvm_kernel_irq_routing_entry *e;
+	struct kvm_kernel_irq_routing_entry entries[KVM_NR_IRQCHIPS];
+	int i, n_entries;
+
+	n_entries = kvm_irq_map_gsi(entries, irq_rt, irqfd->gsi);
 
 	write_seqcount_begin(&irqfd->irq_entry_sc);
 
 	irqfd->irq_entry.type = 0;
-	if (irqfd->gsi >= irq_rt->nr_rt_entries)
-		goto out;
 
-	hlist_for_each_entry(e, &irq_rt->map[irqfd->gsi], link) {
+	e = entries;
+	for (i = 0; i < n_entries; ++i, ++e) {
 		/* Only fast-path MSI. */
 		if (e->type == KVM_IRQ_ROUTING_MSI)
 			irqfd->irq_entry = *e;
 	}
 
- out:
 	write_seqcount_end(&irqfd->irq_entry_sc);
 }
 
diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index a228ee82bad..17584459324 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -160,6 +160,7 @@ static int kvm_set_msi_inatomic(struct kvm_kernel_irq_routing_entry *e,
  */
 int kvm_set_irq_inatomic(struct kvm *kvm, int irq_source_id, u32 irq, int level)
 {
+	struct kvm_kernel_irq_routing_entry entries[KVM_NR_IRQCHIPS];
 	struct kvm_kernel_irq_routing_entry *e;
 	int ret = -EINVAL;
 	struct kvm_irq_routing_table *irq_rt;
@@ -177,14 +178,13 @@ int kvm_set_irq_inatomic(struct kvm *kvm, int irq_source_id, u32 irq, int level)
 	 */
 	idx = srcu_read_lock(&kvm->irq_srcu);
 	irq_rt = srcu_dereference(kvm->irq_routing, &kvm->irq_srcu);
-	if (irq < irq_rt->nr_rt_entries)
-		hlist_for_each_entry(e, &irq_rt->map[irq], link) {
-			if (likely(e->type == KVM_IRQ_ROUTING_MSI))
-				ret = kvm_set_msi_inatomic(e, kvm);
-			else
-				ret = -EWOULDBLOCK;
-			break;
-		}
+	if (kvm_irq_map_gsi(entries, irq_rt, irq) > 0) {
+		e = &entries[0];
+		if (likely(e->type == KVM_IRQ_ROUTING_MSI))
+			ret = kvm_set_msi_inatomic(e, kvm);
+		else
+			ret = -EWOULDBLOCK;
+	}
 	srcu_read_unlock(&kvm->irq_srcu, idx);
 	return ret;
 }
@@ -272,8 +272,7 @@ void kvm_fire_mask_notifiers(struct kvm *kvm, unsigned irqchip, unsigned pin,
 	srcu_read_unlock(&kvm->irq_srcu, idx);
 }
 
-int kvm_set_routing_entry(struct kvm_irq_routing_table *rt,
-			  struct kvm_kernel_irq_routing_entry *e,
+int kvm_set_routing_entry(struct kvm_kernel_irq_routing_entry *e,
 			  const struct kvm_irq_routing_entry *ue)
 {
 	int r = -EINVAL;
@@ -304,7 +303,6 @@ int kvm_set_routing_entry(struct kvm_irq_routing_table *rt,
 		e->irqchip.pin = ue->u.irqchip.pin + delta;
 		if (e->irqchip.pin >= max_pin)
 			goto out;
-		rt->chip[ue->u.irqchip.irqchip][e->irqchip.pin] = ue->gsi;
 		break;
 	case KVM_IRQ_ROUTING_MSI:
 		e->set = kvm_set_msi;
diff --git a/virt/kvm/irqchip.c b/virt/kvm/irqchip.c
index b43c275775c..f4648dd9488 100644
--- a/virt/kvm/irqchip.c
+++ b/virt/kvm/irqchip.c
@@ -31,13 +31,37 @@
 #include <trace/events/kvm.h>
 #include "irq.h"
 
+int kvm_irq_map_gsi(struct kvm_kernel_irq_routing_entry *entries,
+		    struct kvm_irq_routing_table *irq_rt, int gsi)
+{
+	struct kvm_kernel_irq_routing_entry *e;
+	int n = 0;
+
+	if (gsi < irq_rt->nr_rt_entries) {
+		hlist_for_each_entry(e, &irq_rt->map[gsi], link) {
+			entries[n] = *e;
+			++n;
+		}
+	}
+
+	return n;
+}
+
+int kvm_irq_map_chip_pin(struct kvm_irq_routing_table *irq_rt,
+			 unsigned irqchip, unsigned pin)
+{
+	return irq_rt->chip[irqchip][pin];
+}
+
 bool kvm_irq_has_notifier(struct kvm *kvm, unsigned irqchip, unsigned pin)
 {
+	struct kvm_irq_routing_table *irq_rt;
 	struct kvm_irq_ack_notifier *kian;
 	int gsi, idx;
 
 	idx = srcu_read_lock(&kvm->irq_srcu);
-	gsi = srcu_dereference(kvm->irq_routing, &kvm->irq_srcu)->chip[irqchip][pin];
+	irq_rt = srcu_dereference(kvm->irq_routing, &kvm->irq_srcu);
+	gsi = kvm_irq_map_chip_pin(irq_rt, irqchip, pin);
 	if (gsi != -1)
 		hlist_for_each_entry_rcu(kian, &kvm->irq_ack_notifier_list,
 					 link)
@@ -54,13 +78,15 @@ EXPORT_SYMBOL_GPL(kvm_irq_has_notifier);
 
 void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
 {
+	struct kvm_irq_routing_table *irq_rt;
 	struct kvm_irq_ack_notifier *kian;
 	int gsi, idx;
 
 	trace_kvm_ack_irq(irqchip, pin);
 
 	idx = srcu_read_lock(&kvm->irq_srcu);
-	gsi = srcu_dereference(kvm->irq_routing, &kvm->irq_srcu)->chip[irqchip][pin];
+	irq_rt = srcu_dereference(kvm->irq_routing, &kvm->irq_srcu);
+	gsi = kvm_irq_map_chip_pin(irq_rt, irqchip, pin);
 	if (gsi != -1)
 		hlist_for_each_entry_rcu(kian, &kvm->irq_ack_notifier_list,
 					 link)
@@ -115,8 +141,8 @@ int kvm_send_userspace_msi(struct kvm *kvm, struct kvm_msi *msi)
 int kvm_set_irq(struct kvm *kvm, int irq_source_id, u32 irq, int level,
 		bool line_status)
 {
-	struct kvm_kernel_irq_routing_entry *e, irq_set[KVM_NR_IRQCHIPS];
-	int ret = -1, i = 0, idx;
+	struct kvm_kernel_irq_routing_entry irq_set[KVM_NR_IRQCHIPS];
+	int ret = -1, i, idx;
 	struct kvm_irq_routing_table *irq_rt;
 
 	trace_kvm_set_irq(irq, level, irq_source_id);
@@ -127,9 +153,7 @@ int kvm_set_irq(struct kvm *kvm, int irq_source_id, u32 irq, int level,
 	 */
 	idx = srcu_read_lock(&kvm->irq_srcu);
 	irq_rt = srcu_dereference(kvm->irq_routing, &kvm->irq_srcu);
-	if (irq < irq_rt->nr_rt_entries)
-		hlist_for_each_entry(e, &irq_rt->map[irq], link)
-			irq_set[i++] = *e;
+	i = kvm_irq_map_gsi(irq_set, irq_rt, irq);
 	srcu_read_unlock(&kvm->irq_srcu, idx);
 
 	while(i--) {
@@ -171,9 +195,11 @@ static int setup_routing_entry(struct kvm_irq_routing_table *rt,
 
 	e->gsi = ue->gsi;
 	e->type = ue->type;
-	r = kvm_set_routing_entry(rt, e, ue);
+	r = kvm_set_routing_entry(e, ue);
 	if (r)
 		goto out;
+	if (e->type == KVM_IRQ_ROUTING_IRQCHIP)
+		rt->chip[e->irqchip.irqchip][e->irqchip.pin] = e->gsi;
 
 	hlist_add_head(&e->link, &rt->map[e->gsi]);
 	r = 0;