2 files changed, 28 insertions, 0 deletions

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 4f0f22b020ea..f64e9798129c 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -557,6 +557,33 @@ out:
         put_cpu();
 }
 
+/* Rebind a new event channel to an existing irq. */
+void rebind_evtchn_irq(int evtchn, int irq)
+{
+        /* Make sure the irq is masked, since the new event channel
+           will also be masked. */
+        disable_irq(irq);
+
+        spin_lock(&irq_mapping_update_lock);
+
+        /* After resume the irq<->evtchn mappings are all cleared out */
+        BUG_ON(evtchn_to_irq[evtchn] != -1);
+        /* Expect irq to have been bound before,
+           so the bindcount should be non-0 */
+        BUG_ON(irq_bindcount[irq] == 0);
+
+        evtchn_to_irq[evtchn] = irq;
+        irq_info[irq] = mk_irq_info(IRQT_EVTCHN, 0, evtchn);
+
+        spin_unlock(&irq_mapping_update_lock);
+
+        /* new event channels are always bound to cpu 0 */
+        irq_set_affinity(irq, cpumask_of_cpu(0));
+
+        /* Unmask the event channel. */
+        enable_irq(irq);
+}
+
 /* Rebind an evtchn so that it gets delivered to a specific cpu */
 static void rebind_irq_to_cpu(unsigned irq, unsigned tcpu)
 {
diff --git a/include/xen/events.h b/include/xen/events.h
index acd8e062c85f..a82ec0c45c38 100644
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -32,6 +32,7 @@ void unbind_from_irqhandler(unsigned int irq, void *dev_id);
 
 void xen_send_IPI_one(unsigned int cpu, enum ipi_vector vector);
 int resend_irq_on_evtchn(unsigned int irq);
+void rebind_evtchn_irq(int evtchn, int irq);
 
 static inline void notify_remote_via_evtchn(int port)
 {