Index: root/xen-unstable.hg/linux-2.6-xen-sparse/drivers/xen/tpmback/xenbus.c
===================================================================
--- root.orig/xen-unstable.hg/linux-2.6-xen-sparse/drivers/xen/tpmback/xenbus.c
+++ root/xen-unstable.hg/linux-2.6-xen-sparse/drivers/xen/tpmback/xenbus.c
@@ -45,6 +45,14 @@ static void backend_changed(struct xenbu
 static void frontend_changed(struct xenbus_device *dev,
 			     enum xenbus_state frontend_state);
 
+long int tpmback_get_instance(struct backend_info *bi)
+{
+	long int res = -1;
+	if (bi && bi->is_instance_set)
+		res = bi->instance;
+	return res;
+}
+
 static int tpmback_remove(struct xenbus_device *dev)
 {
 	struct backend_info *be = dev->dev.driver_data;
@@ -57,6 +65,7 @@ static int tpmback_remove(struct xenbus_
 		be->backend_watch.node = NULL;
 	}
 	if (be->tpmif) {
+		be->tpmif->bi = NULL;
 		vtpm_release_packets(be->tpmif, 0);
 		tpmif_put(be->tpmif);
 		be->tpmif = NULL;
@@ -150,7 +159,7 @@ static void frontend_changed(struct xenb
 		break;
 
 	case XenbusStateClosing:
-		be->tpmif->tpm_instance = -1;
+		be->instance = -1;
 		break;
 
 	case XenbusStateClosed:
@@ -256,8 +265,7 @@ static int connect_ring(struct backend_i
 	}
 
 	if (!be->tpmif) {
-		be->tpmif = tpmif_find(dev->otherend_id,
-				       be->instance);
+		be->tpmif = tpmif_find(dev->otherend_id, be);
 		if (IS_ERR(be->tpmif)) {
 			err = PTR_ERR(be->tpmif);
 			be->tpmif = NULL;
Index: root/xen-unstable.hg/linux-2.6-xen-sparse/drivers/xen/tpmback/common.h
===================================================================
--- root.orig/xen-unstable.hg/linux-2.6-xen-sparse/drivers/xen/tpmback/common.h
+++ root/xen-unstable.hg/linux-2.6-xen-sparse/drivers/xen/tpmback/common.h
@@ -21,6 +21,8 @@
 	pr_debug("(file=%s, line=%d) " _f,	\
 		 __FILE__ , __LINE__ , ## _a )
 
+struct backend_info;
+
 typedef struct tpmif_st {
 	struct list_head tpmif_list;
 	/* Unique identifier for this interface. */
@@ -43,7 +45,7 @@ typedef struct tpmif_st {
 	struct list_head list;	/* scheduling list */
 	atomic_t refcnt;
 
-	long int tpm_instance;
+	struct backend_info *bi;
 	unsigned long mmap_vstart;
 
 	grant_handle_t shmem_handle;
@@ -54,7 +56,7 @@ typedef struct tpmif_st {
 } tpmif_t;
 
 void tpmif_disconnect_complete(tpmif_t * tpmif);
-tpmif_t *tpmif_find(domid_t domid, long int instance);
+tpmif_t *tpmif_find(domid_t domid, struct backend_info *bi);
 void tpmif_interface_init(void);
 void tpmif_interface_exit(void);
 void tpmif_schedule_work(tpmif_t * tpmif);
@@ -66,8 +68,11 @@ irqreturn_t tpmif_be_int(int irq, void *
 int tpmif_vtpm_open(tpmif_t *tpmif, domid_t domain, u32 instance);
 int tpmif_vtpm_close(u32 instance);
 
+long int tpmback_get_instance(struct backend_info *bi);
+
 int vtpm_release_packets(tpmif_t * tpmif, int send_msgs);
 
+
 #define tpmif_get(_b) (atomic_inc(&(_b)->refcnt))
 #define tpmif_put(_b)					\
 	do {						\
Index: root/xen-unstable.hg/linux-2.6-xen-sparse/drivers/xen/tpmback/interface.c
===================================================================
--- root.orig/xen-unstable.hg/linux-2.6-xen-sparse/drivers/xen/tpmback/interface.c
+++ root/xen-unstable.hg/linux-2.6-xen-sparse/drivers/xen/tpmback/interface.c
@@ -20,7 +20,7 @@ int num_frontends = 0;
 
 LIST_HEAD(tpmif_list);
 
-static tpmif_t *alloc_tpmif(domid_t domid, long int instance)
+static tpmif_t *alloc_tpmif(domid_t domid, struct backend_info *bi)
 {
 	tpmif_t *tpmif;
 
@@ -31,7 +31,7 @@ static tpmif_t *alloc_tpmif(domid_t domi
 	memset(tpmif, 0, sizeof (*tpmif));
 	tpmif->domid = domid;
 	tpmif->status = DISCONNECTED;
-	tpmif->tpm_instance = instance;
+	tpmif->bi = bi;
 	snprintf(tpmif->devname, sizeof(tpmif->devname), "tpmif%d", domid);
 	atomic_set(&tpmif->refcnt, 1);
 
@@ -54,12 +54,12 @@ static void free_tpmif(tpmif_t * tpmif)
 	kmem_cache_free(tpmif_cachep, tpmif);
 }
 
-tpmif_t *tpmif_find(domid_t domid, long int instance)
+tpmif_t *tpmif_find(domid_t domid, struct backend_info *bi)
 {
 	tpmif_t *tpmif;
 
 	list_for_each_entry(tpmif, &tpmif_list, tpmif_list) {
-		if (tpmif->tpm_instance == instance) {
+		if (tpmif->bi == bi) {
 			if (tpmif->domid == domid) {
 				tpmif_get(tpmif);
 				return tpmif;
@@ -69,7 +69,7 @@ tpmif_t *tpmif_find(domid_t domid, long 
 		}
 	}
 
-	return alloc_tpmif(domid, instance);
+	return alloc_tpmif(domid, bi);
 }
 
 static int map_frontend_page(tpmif_t *tpmif, unsigned long shared_page)
Index: root/xen-unstable.hg/linux-2.6-xen-sparse/drivers/xen/tpmback/tpmback.c
===================================================================
--- root.orig/xen-unstable.hg/linux-2.6-xen-sparse/drivers/xen/tpmback/tpmback.c
+++ root/xen-unstable.hg/linux-2.6-xen-sparse/drivers/xen/tpmback/tpmback.c
@@ -161,7 +161,7 @@ static struct packet *packet_alloc(tpmif
 	if (NULL != pak) {
 		if (tpmif) {
 			pak->tpmif = tpmif;
-			pak->tpm_instance = tpmif->tpm_instance;
+			pak->tpm_instance = tpmback_get_instance(tpmif->bi);
 			tpmif_get(tpmif);
 		}
 		pak->data_len = size;