[PATCH 5/8] KVM: Add kvm_get_irq_routing_entry() func

[Sheng Yang <sheng@linux.intel.com>]

We need to query the entry later.

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
---
 include/linux/kvm_host.h |    2 ++
 virt/kvm/irq_comm.c      |   20 ++++++++++++++++++++
 2 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 7f9e4b7..30f83cd 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -614,6 +614,8 @@ int kvm_set_irq_routing(struct kvm *kvm,
 			const struct kvm_irq_routing_entry *entries,
 			unsigned nr,
 			unsigned flags);
+struct kvm_kernel_irq_routing_entry *kvm_get_irq_routing_entry(struct kvm *kvm,
+							int gsi);
 void kvm_free_irq_routing(struct kvm *kvm);
 
 #else
diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index 8edca91..80ced8c 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -421,6 +421,26 @@ out:
 	return r;
 }
 
+struct kvm_kernel_irq_routing_entry *kvm_get_irq_routing_entry(struct kvm *kvm,
+							       int gsi)
+{
+	int count = 0;
+	struct kvm_kernel_irq_routing_entry *ei = NULL;
+	struct kvm_irq_routing_table *irq_rt;
+	struct hlist_node *n;
+
+	rcu_read_lock();
+	irq_rt = rcu_dereference(kvm->irq_routing);
+	if (gsi < irq_rt->nr_rt_entries)
+		hlist_for_each_entry(ei, n, &irq_rt->map[gsi], link)
+			count++;
+	rcu_read_unlock();
+	if (count == 1)
+		return ei;
+
+	return NULL;
+}
+
 #define IOAPIC_ROUTING_ENTRY(irq) \
 	{ .gsi = irq, .type = KVM_IRQ_ROUTING_IRQCHIP,	\
 	  .u.irqchip.irqchip = KVM_IRQCHIP_IOAPIC, .u.irqchip.pin = (irq) }
-- 
1.7.0.1