diff --git a/drivers/xen/evtchn.c b/drivers/xen/evtchn.c
index 00f40f0..38272ad 100644
--- a/drivers/xen/evtchn.c
+++ b/drivers/xen/evtchn.c
@@ -49,6 +49,8 @@
 #include <linux/init.h>
 #include <linux/mutex.h>
 #include <linux/cpu.h>
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
 
 #include <xen/xen.h>
 #include <xen/events.h>
@@ -58,10 +60,10 @@
 struct per_user_data {
 	struct mutex bind_mutex; /* serialize bind/unbind operations */
 	struct rb_root evtchns;
+	unsigned int nr_evtchns;
 
 	/* Notification ring, accessed via /dev/xen/evtchn. */
-#define EVTCHN_RING_SIZE     (PAGE_SIZE / sizeof(evtchn_port_t))
-#define EVTCHN_RING_MASK(_i) ((_i)&(EVTCHN_RING_SIZE-1))
+	unsigned int ring_size;
 	evtchn_port_t *ring;
 	unsigned int ring_cons, ring_prod, ring_overflow;
 	struct mutex ring_cons_mutex; /* protect against concurrent readers */
@@ -80,10 +82,41 @@
 	bool enabled;
 };
 
+static evtchn_port_t *evtchn_alloc_ring(unsigned int size)
+{
+	evtchn_port_t *ring;
+	size_t s = size * sizeof(*ring);
+
+	ring = kmalloc(s, GFP_KERNEL);
+	if (!ring)
+		ring = vmalloc(s);
+
+	return ring;
+}
+
+static void evtchn_free_ring(evtchn_port_t *ring)
+{
+	kvfree(ring);
+}
+
+static unsigned int evtchn_ring_offset(struct per_user_data *u,
+				       unsigned int idx)
+{
+	return idx & (u->ring_size - 1);
+}
+
+static evtchn_port_t *evtchn_ring_entry(struct per_user_data *u,
+					unsigned int idx)
+{
+	return u->ring + evtchn_ring_offset(u, idx);
+}
+
 static int add_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
 {
 	struct rb_node **new = &(u->evtchns.rb_node), *parent = NULL;
 
+	u->nr_evtchns++;
+
 	while (*new) {
 		struct user_evtchn *this;
 
@@ -107,6 +140,7 @@
 
 static void del_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
 {
+	u->nr_evtchns--;
 	rb_erase(&evtchn->node, &u->evtchns);
 	kfree(evtchn);
 }
@@ -144,8 +178,8 @@
 
 	spin_lock(&u->ring_prod_lock);
 
-	if ((u->ring_prod - u->ring_cons) < EVTCHN_RING_SIZE) {
-		u->ring[EVTCHN_RING_MASK(u->ring_prod)] = evtchn->port;
+	if ((u->ring_prod - u->ring_cons) < u->ring_size) {
+		*evtchn_ring_entry(u, u->ring_prod) = evtchn->port;
 		wmb(); /* Ensure ring contents visible */
 		if (u->ring_cons == u->ring_prod++) {
 			wake_up_interruptible(&u->evtchn_wait);
@@ -200,10 +234,10 @@
 	}
 
 	/* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */
-	if (((c ^ p) & EVTCHN_RING_SIZE) != 0) {
-		bytes1 = (EVTCHN_RING_SIZE - EVTCHN_RING_MASK(c)) *
+	if (((c ^ p) & u->ring_size) != 0) {
+		bytes1 = (u->ring_size - evtchn_ring_offset(u, c)) *
 			sizeof(evtchn_port_t);
-		bytes2 = EVTCHN_RING_MASK(p) * sizeof(evtchn_port_t);
+		bytes2 = evtchn_ring_offset(u, p) * sizeof(evtchn_port_t);
 	} else {
 		bytes1 = (p - c) * sizeof(evtchn_port_t);
 		bytes2 = 0;
@@ -219,7 +253,7 @@
 
 	rc = -EFAULT;
 	rmb(); /* Ensure that we see the port before we copy it. */
-	if (copy_to_user(buf, &u->ring[EVTCHN_RING_MASK(c)], bytes1) ||
+	if (copy_to_user(buf, evtchn_ring_entry(u, c), bytes1) ||
 	    ((bytes2 != 0) &&
 	     copy_to_user(&buf[bytes1], &u->ring[0], bytes2)))
 		goto unlock_out;
@@ -278,6 +312,66 @@
 	return rc;
 }
 
+static int evtchn_resize_ring(struct per_user_data *u)
+{
+	unsigned int new_size;
+	evtchn_port_t *new_ring, *old_ring;
+	unsigned int p, c;
+
+	/*
+	 * Ensure the ring is large enough to capture all possible
+	 * events. i.e., one free slot for each bound event.
+	 */
+	if (u->nr_evtchns <= u->ring_size)
+		return 0;
+
+	if (u->ring_size == 0)
+		new_size = 64;
+	else
+		new_size = 2 * u->ring_size;
+
+	new_ring = evtchn_alloc_ring(new_size);
+	if (!new_ring)
+		return -ENOMEM;
+
+	old_ring = u->ring;
+
+	/*
+	 * Access to the ring contents is serialized by either the
+	 * prod /or/ cons lock so take both when resizing.
+	 */
+	mutex_lock(&u->ring_cons_mutex);
+	spin_lock_irq(&u->ring_prod_lock);
+
+	/*
+	 * Copy the old ring contents to the new ring.
+	 *
+	 * If the ring contents crosses the end of the current ring,
+	 * it needs to be copied in two chunks.
+	 *
+	 * +---------+    +------------------+
+	 * |34567  12| -> |       1234567    |
+	 * +-----p-c-+    +------------------+
+	 */
+	p = evtchn_ring_offset(u, u->ring_prod);
+	c = evtchn_ring_offset(u, u->ring_cons);
+	if (p < c) {
+		memcpy(new_ring + c, u->ring + c, (u->ring_size - c) * sizeof(*u->ring));
+		memcpy(new_ring + u->ring_size, u->ring, p * sizeof(*u->ring));
+	} else
+		memcpy(new_ring + c, u->ring + c, (p - c) * sizeof(*u->ring));
+
+	u->ring = new_ring;
+	u->ring_size = new_size;
+
+	spin_unlock_irq(&u->ring_prod_lock);
+	mutex_unlock(&u->ring_cons_mutex);
+
+	evtchn_free_ring(old_ring);
+
+	return 0;
+}
+
 static int evtchn_bind_to_user(struct per_user_data *u, int port)
 {
 	struct user_evtchn *evtchn;
@@ -305,6 +399,10 @@
 	if (rc < 0)
 		goto err;
 
+	rc = evtchn_resize_ring(u);
+	if (rc < 0)
+		goto err;
+
 	rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, 0,
 				       u->name, evtchn);
 	if (rc < 0)
@@ -503,13 +601,6 @@
 
 	init_waitqueue_head(&u->evtchn_wait);
 
-	u->ring = (evtchn_port_t *)__get_free_page(GFP_KERNEL);
-	if (u->ring == NULL) {
-		kfree(u->name);
-		kfree(u);
-		return -ENOMEM;
-	}
-
 	mutex_init(&u->bind_mutex);
 	mutex_init(&u->ring_cons_mutex);
 	spin_lock_init(&u->ring_prod_lock);
@@ -532,7 +623,7 @@
 		evtchn_unbind_from_user(u, evtchn);
 	}
 
-	free_page((unsigned long)u->ring);
+	evtchn_free_ring(u->ring);
 	kfree(u->name);
 	kfree(u);