[IA64-SGI] get XPC to cleanly disengage from remote memory references

When XPC is being shutdown (i.e., rmmod, reboot) it doesn't ensure that
other partitions with whom it was connected have completely disengaged
from any attempt at cross-partition memory references. This can lead to
MCAs in any of these other partitions when the partition is reset.
Signed-off-by: Dean Nelson <dcn@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

include/asm-ia64/sn/xp.h

@@ -217,7 +217,15 @@ enum xpc_retval {
 	xpcInvalidPartid,	/* 42: invalid partition ID */
 	xpcLocalPartid,		/* 43: local partition ID */
 
-	xpcUnknownReason	/* 44: unknown reason -- must be last in list */
+	xpcOtherGoingDown,	/* 44: other side going down, reason unknown */
+	xpcSystemGoingDown,	/* 45: system is going down, reason unknown */
+	xpcSystemHalt,		/* 46: system is being halted */
+	xpcSystemReboot,	/* 47: system is being rebooted */
+	xpcSystemPoweroff,	/* 48: system is being powered off */
+
+	xpcDisconnecting,	/* 49: channel disconnecting (closing) */
+
+	xpcUnknownReason	/* 50: unknown reason -- must be last in list */
 };