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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Wesley Sheng <wesley.sheng@microchip.com>,
        Kelvin Cao <kelvin.cao@microchip.com>,
        Jon Mason <jdmason@kudzu.us>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.16 0820/1039] ntb_hw_switchtec: Fix bug with more than 32 partitions
Date:   Mon, 24 Jan 2022 19:43:29 +0100
Message-Id: <20220124184152.866189101@linuxfoundation.org>
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From: Wesley Sheng <wesley.sheng@microchip.com>

[ 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@microchip.com>
Signed-off-by: Kelvin Cao <kelvin.cao@microchip.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/ntb/hw/mscc/ntb_hw_switchtec.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

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");
-- 
2.34.1