x86: Fix UV BAU destination subnode id

The SGI UV Broadcast Assist Unit is used to send TLB shootdown
messages to remote nodes of the system.  The header of the
message must contain the subnode id of the block in the
receiving hub that handles such messages.  It should always be
0x10, the id of the "LB" block.

It had previously been documented as a "must be zero" field.
Signed-off-by: Cliff Wickman <cpw@sgi.com>
Acked-by: Jack Steiner <steiner@sgi.com>
LKML-Reference: <E1Mc1x7-0005Ce-6t@eag09.americas.sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/include/asm/uv/uv_bau.h

@@ -133,7 +133,7 @@ struct bau_msg_payload {
  * see table 4.2.3.0.1 in broacast_assist spec.
  */
 struct bau_msg_header {
-	unsigned int dest_subnodeid:6;	/* must be zero */
+	unsigned int dest_subnodeid:6;	/* must be 0x10, for the LB */
 	/* bits 5:0 */
 	unsigned int base_dest_nodeid:15; /* nasid>>1 (pnode) of */
 	/* bits 20:6 */			  /* first bit in node_map */

arch/x86/kernel/tlb_uv.c

@@ -744,6 +744,7 @@ uv_activation_descriptor_init(int node, int pnode)
 		 * note that base_dest_nodeid is actually a nasid.
 		 */
 		ad2->header.base_dest_nodeid = uv_partition_base_pnode << 1;
+		ad2->header.dest_subnodeid = 0x10; /* the LB */
 		ad2->header.command = UV_NET_ENDPOINT_INTD;
 		ad2->header.int_both = 1;
 		/*