Patch "ntb_hw_switchtec: Fix bug with more than 32 partitions" 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

    ntb_hw_switchtec: Fix bug with more than 32 partitions

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:
     ntb_hw_switchtec-fix-bug-with-more-than-32-partition.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 a6e7adb217b0624700bca3962e0b45743c8e17dc
Author: Wesley Sheng <wesley.sheng@xxxxxxxxxxxxx>
Date:   Thu Dec 23 17:23:30 2021 -0800

    ntb_hw_switchtec: Fix bug with more than 32 partitions
    
    [ Upstream commit 7ff351c86b6b258f387502ab2c9b9d04f82c1c3d ]
    
    Switchtec could support as mush as 48 partitions, but ffs & fls are
    for 32 bit argument, in case of partition index larger than 31, the
    current code could not parse the peer partition index correctly.
    Change to the 64 bit version __ffs64 & fls64 accordingly to fix this
    bug.
    
    Fixes: 3df54c870f52 ("ntb_hw_switchtec: Allow using Switchtec NTB in multi-partition setups")
    Signed-off-by: Wesley Sheng <wesley.sheng@xxxxxxxxxxxxx>
    Signed-off-by: Kelvin Cao <kelvin.cao@xxxxxxxxxxxxx>
    Signed-off-by: Jon Mason <jdmason@xxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/ntb/hw/mscc/ntb_hw_switchtec.c b/drivers/ntb/hw/mscc/ntb_hw_switchtec.c
index 6603c77c0a848..ec9cb6c81edae 100644
--- a/drivers/ntb/hw/mscc/ntb_hw_switchtec.c
+++ b/drivers/ntb/hw/mscc/ntb_hw_switchtec.c
@@ -840,7 +840,6 @@ static int switchtec_ntb_init_sndev(struct switchtec_ntb *sndev)
 	u64 tpart_vec;
 	int self;
 	u64 part_map;
-	int bit;
 
 	sndev->ntb.pdev = sndev->stdev->pdev;
 	sndev->ntb.topo = NTB_TOPO_SWITCH;
@@ -861,29 +860,28 @@ static int switchtec_ntb_init_sndev(struct switchtec_ntb *sndev)
 	part_map = ioread64(&sndev->mmio_ntb->ep_map);
 	part_map &= ~(1 << sndev->self_partition);
 
-	if (!ffs(tpart_vec)) {
+	if (!tpart_vec) {
 		if (sndev->stdev->partition_count != 2) {
 			dev_err(&sndev->stdev->dev,
 				"ntb target partition not defined\n");
 			return -ENODEV;
 		}
 
-		bit = ffs(part_map);
-		if (!bit) {
+		if (!part_map) {
 			dev_err(&sndev->stdev->dev,
 				"peer partition is not NT partition\n");
 			return -ENODEV;
 		}
 
-		sndev->peer_partition = bit - 1;
+		sndev->peer_partition = __ffs64(part_map);
 	} else {
-		if (ffs(tpart_vec) != fls(tpart_vec)) {
+		if (__ffs64(tpart_vec) != (fls64(tpart_vec) - 1)) {
 			dev_err(&sndev->stdev->dev,
 				"ntb driver only supports 1 pair of 1-1 ntb mapping\n");
 			return -ENODEV;
 		}
 
-		sndev->peer_partition = ffs(tpart_vec) - 1;
+		sndev->peer_partition = __ffs64(tpart_vec);
 		if (!(part_map & (1ULL << sndev->peer_partition))) {
 			dev_err(&sndev->stdev->dev,
 				"ntb target partition is not NT partition\n");