diff -r 61c96456a3e1 drivers/char/tpm/tpm_vtpm.c
--- a/drivers/char/tpm/tpm_vtpm.c	Thu Dec 20 16:58:14 2007 +0000
+++ b/drivers/char/tpm/tpm_vtpm.c	Wed Jan 02 14:19:04 2008 -0500
@@ -307,6 +307,7 @@ static int vtpm_send(struct tpm_chip *ch
 			rc = vtpm_vd_send(vtpms->tpm_private,
 			                  buf,
 			                  count,
+			                  0,
 			                  t);
 			/*
 			 * The generic TPM driver will call
@@ -368,6 +369,7 @@ static int _vtpm_send_queued(struct tpm_
 		rc = vtpm_vd_send(vtpms->tpm_private,
 		                  qt->request,
 		                  qt->request_len,
+		                  0,
 		                  qt);
 
 		if (rc < 0) {
diff -r 61c96456a3e1 drivers/char/tpm/tpm_vtpm.h
--- a/drivers/char/tpm/tpm_vtpm.h	Thu Dec 20 16:58:14 2007 +0000
+++ b/drivers/char/tpm/tpm_vtpm.h	Wed Jan 02 14:19:04 2008 -0500
@@ -35,7 +35,7 @@ enum vdev_status {
 
 /* this function is called from tpm_vtpm.c */
 int vtpm_vd_send(struct tpm_private * tp,
-                 const u8 * buf, size_t count, void *ptr);
+                 const u8 * buf, size_t count, u8 locality, void *ptr);
 
 /* these functions are offered by tpm_vtpm.c */
 struct tpm_chip *init_vtpm(struct device *,
diff -r 61c96456a3e1 drivers/char/tpm/tpm_xen.c
--- a/drivers/char/tpm/tpm_xen.c	Thu Dec 20 16:58:14 2007 +0000
+++ b/drivers/char/tpm/tpm_xen.c	Wed Jan 02 14:19:04 2008 -0500
@@ -98,7 +98,7 @@ static void tpmif_set_connected_state(st
                                       u8 newstate);
 static int tpm_xmit(struct tpm_private *tp,
                     const u8 * buf, size_t count, int userbuffer,
-                    void *remember);
+                    u8 locality, void *remember);
 static void destroy_tpmring(struct tpm_private *tp);
 void __exit tpmif_exit(void);
 
@@ -211,12 +211,12 @@ static DEFINE_MUTEX(suspend_lock);
  * Send data via this module by calling this function
  */
 int vtpm_vd_send(struct tpm_private *tp,
-                 const u8 * buf, size_t count, void *ptr)
+                 const u8 * buf, size_t count, u8 locality, void *ptr)
 {
 	int sent;
 
 	mutex_lock(&suspend_lock);
-	sent = tpm_xmit(tp, buf, count, 0, ptr);
+	sent = tpm_xmit(tp, buf, count, 0, locality, ptr);
 	mutex_unlock(&suspend_lock);
 
 	return sent;
@@ -239,6 +239,7 @@ static int setup_tpmring(struct xenbus_d
 		xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
 		return -ENOMEM;
 	}
+	memset(sring, 0, PAGE_SIZE);
 	tp->tx = sring;
 
 	err = xenbus_grant_ring(dev, virt_to_mfn(tp->tx));
@@ -573,7 +574,7 @@ static irqreturn_t tpmif_int(int irq, vo
 
 static int tpm_xmit(struct tpm_private *tp,
                     const u8 * buf, size_t count, int isuserbuffer,
-                    void *remember)
+                    u8 locality, void *remember)
 {
 	tpmif_tx_request_t *tx;
 	TPMIF_RING_IDX i;
@@ -617,6 +618,8 @@ static int tpm_xmit(struct tpm_private *
 		tx = &tp->tx->ring[i].req;
 		tx->addr = virt_to_machine(txb->data);
 		tx->size = txb->len;
+		tx->version = 1;
+		tx->locality = locality;
 
 		DPRINTK("First 4 characters sent by TPM-FE are "
 			"0x%02x 0x%02x 0x%02x 0x%02x\n",
diff -r 61c96456a3e1 drivers/xen/tpmback/tpmback.c
--- a/drivers/xen/tpmback/tpmback.c	Thu Dec 20 16:58:14 2007 +0000
+++ b/drivers/xen/tpmback/tpmback.c	Wed Jan 02 14:19:04 2008 -0500
@@ -298,6 +298,18 @@ int _packet_write(struct packet *pak,
 	return rc;
 }
 
+
+static u8 get_locty_ring(tpmif_t *tpmif)
+{
+	tpmif_tx_request_t *tx = &tpmif->tx->ring[0].req;
+
+	if (tx->version == 1)
+		return tx->locality;
+
+	return 0;
+}
+
+
 /*
  * Read data from the shared memory and copy it directly into the
  * provided buffer. Advance the read_last indicator which tells
@@ -319,9 +331,11 @@ static int packet_read(struct packet *pa
 
 	if (pak->last_read < 4) {
 		/*
-		 * copy the instance number into the buffer
+		 * copy the instance number into the buffer along
+		 * with locality information.
 		 */
-		u32 instance_no = htonl(pak->tpm_instance);
+		u32 instance_no = htonl(pak->tpm_instance |
+		                        get_locty_ring(pak->tpmif) << 29);
 		u32 last_read = pak->last_read;
 
 		to_copy = min_t(size_t, 4 - last_read, numbytes);
diff -r 61c96456a3e1 include/xen/interface/io/tpmif.h
--- a/include/xen/interface/io/tpmif.h	Thu Dec 20 16:58:14 2007 +0000
+++ b/include/xen/interface/io/tpmif.h	Wed Jan 02 14:19:04 2008 -0500
@@ -39,7 +39,8 @@ struct tpmif_tx_request {
 struct tpmif_tx_request {
     unsigned long addr;   /* Machine address of packet.   */
     grant_ref_t ref;      /* grant table access reference */
-    uint16_t unused;
+    uint8_t version;      /* version of block */
+    uint8_t locality;     /* locality for command */
     uint16_t size;        /* Packet size in bytes.        */
 };
 typedef struct tpmif_tx_request tpmif_tx_request_t;