Patch "powerpc/pseries: Fix numa FORM2 parsing fallback code" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    powerpc/pseries: Fix numa FORM2 parsing fallback code

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     powerpc-pseries-fix-numa-form2-parsing-fallback-code.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 420021eccdcb9e222774e22f715f5b2b1bc11809
Author: Nicholas Piggin <npiggin@xxxxxxxxx>
Date:   Tue Nov 9 16:49:00 2021 +1000

    powerpc/pseries: Fix numa FORM2 parsing fallback code
    
    [ Upstream commit 302039466f6a3b9421ecb9a6a2c528801dc24a86 ]
    
    In case the FORM2 distance table from firmware is not the expected size,
    there is fallback code that just populates the lookup table as local vs
    remote.
    
    However it then continues on to use the distance table. Fix.
    
    Fixes: 1c6b5a7e7405 ("powerpc/pseries: Add support for FORM2 associativity")
    Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx>
    Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
    Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20211109064900.2041386-2-npiggin@xxxxxxxxx
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 53e9901409163..59d3cfcd78879 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -407,30 +407,26 @@ static void initialize_form2_numa_distance_lookup_table(void)
 
 	if (form2_distances_length != max_numa_index * max_numa_index) {
 		WARN(1, "Wrong NUMA distance information\n");
-		/* consider everybody else just remote. */
-		for (i = 0;  i < max_numa_index; i++) {
-			for (j = 0; j < max_numa_index; j++) {
-				int nodeA = numa_id_index_table[i];
-				int nodeB = numa_id_index_table[j];
-
-				if (nodeA == nodeB)
-					numa_distance_table[nodeA][nodeB] = LOCAL_DISTANCE;
-				else
-					numa_distance_table[nodeA][nodeB] = REMOTE_DISTANCE;
-			}
-		}
+		form2_distances = NULL; // don't use it
 	}
-
 	distance_index = 0;
 	for (i = 0;  i < max_numa_index; i++) {
 		for (j = 0; j < max_numa_index; j++) {
 			int nodeA = numa_id_index_table[i];
 			int nodeB = numa_id_index_table[j];
-
-			numa_distance_table[nodeA][nodeB] = form2_distances[distance_index++];
-			pr_debug("dist[%d][%d]=%d ", nodeA, nodeB, numa_distance_table[nodeA][nodeB]);
+			int dist;
+
+			if (form2_distances)
+				dist = form2_distances[distance_index++];
+			else if (nodeA == nodeB)
+				dist = LOCAL_DISTANCE;
+			else
+				dist = REMOTE_DISTANCE;
+			numa_distance_table[nodeA][nodeB] = dist;
+			pr_debug("dist[%d][%d]=%d ", nodeA, nodeB, dist);
 		}
 	}
+
 	of_node_put(root);
 }