KVM: Maintain back mapping from irqchip/pin to gsi

Maintain back mapping from irqchip/pin to gsi to speedup
interrupt acknowledgment notifications.

[avi: build fix on non-x86/ia64]

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index f403e66..cc2d749 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -131,7 +131,10 @@
 	struct hlist_node link;
 };
 
+#ifdef __KVM_HAVE_IOAPIC
+
 struct kvm_irq_routing_table {
+	int chip[KVM_NR_IRQCHIPS][KVM_IOAPIC_NUM_PINS];
 	struct kvm_kernel_irq_routing_entry *rt_entries;
 	u32 nr_rt_entries;
 	/*
@@ -141,6 +144,12 @@
 	struct hlist_head map[0];
 };
 
+#else
+
+struct kvm_irq_routing_table {};
+
+#endif
+
 struct kvm {
 	spinlock_t mmu_lock;
 	spinlock_t requests_lock;