sgi-xpc: XPC fails to discover partitions with all nasids above 128

UV hardware defines 256 memory protection regions versus the baseline 64
with increasing size for the SN2 ia64.  This was overlooked when XPC was
modified to accomodate both UV and SN2.

Without this patch, a user could reconfigure their existing system and
suddenly disable cross-partition communications with no indication of what
has gone wrong.  It also prevents larger configurations from using
cross-partition communication.

Signed-off-by: Robin Holt <holt@sgi.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/misc/sgi-xp/xpc_partition.c b/drivers/misc/sgi-xp/xpc_partition.c
index d551f09ccb792175d49a83c4a929df7394f50a8a..6956f7e7d43921ec80f5e450a471429bc21f55fc 100644 (file)
--- a/drivers/misc/sgi-xp/xpc_partition.c
+++ b/drivers/misc/sgi-xp/xpc_partition.c
@@ -439,18 +439,23 @@ xpc_discovery(void)
         * nodes that can comprise an access protection grouping. The access
         * protection is in regards to memory, IOI and IPI.
         */
-       max_regions = 64;
        region_size = xp_region_size;
 
-       switch (region_size) {
-       case 128:
-               max_regions *= 2;
-       case 64:
-               max_regions *= 2;
-       case 32:
-               max_regions *= 2;
-               region_size = 16;
-               DBUG_ON(!is_shub2());
+       if (is_uv())
+               max_regions = 256;
+       else {
+               max_regions = 64;
+
+               switch (region_size) {
+               case 128:
+                       max_regions *= 2;
+               case 64:
+                       max_regions *= 2;
+               case 32:
+                       max_regions *= 2;
+                       region_size = 16;
+                       DBUG_ON(!is_shub2());
+               }
        }
 
        for (region = 0; region < max_regions; region++) {