bnxt_en: Fix memory corruption when FW resources change during ifdown

[ Upstream commit 2747328 ]

bnxt_set_dflt_rings() assumes that it is always called before any TC has
been created.  So it doesn't take bp->num_tc into account and assumes
that it is always 0 or 1.

In the FW resource or capability change scenario, the FW will return
flags in bnxt_hwrm_if_change() that will cause the driver to
reinitialize and call bnxt_cancel_reservations().  This will lead to
bnxt_init_dflt_ring_mode() calling bnxt_set_dflt_rings() and bp->num_tc
may be greater than 1.  This will cause bp->tx_ring[] to be sized too
small and cause memory corruption in bnxt_alloc_cp_rings().

Fix it by properly scaling the TX rings by bp->num_tc in the code
paths mentioned above.  Add 2 helper functions to determine
bp->tx_nr_rings and bp->tx_nr_rings_per_tc.

Fixes: ec5d31e ("bnxt_en: Handle firmware reset status during IF_UP.")
Reviewed-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Reviewed-by: Andy Gospodarek <andrew.gospodarek@broadcom.com>
Signed-off-by: Sreekanth Reddy <sreekanth.reddy@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Link: https://patch.msgid.link/20250825175927.459987-2-michael.chan@broadcom.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: sreekanthbrcm

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -12844,6 +12844,17 @@ static int bnxt_set_xps_mapping(struct bnxt *bp)
 	return rc;
 }
 
+static int bnxt_tx_nr_rings(struct bnxt *bp)
+{
+	return bp->num_tc ? bp->tx_nr_rings_per_tc * bp->num_tc :
+			    bp->tx_nr_rings_per_tc;
+}
+
+static int bnxt_tx_nr_rings_per_tc(struct bnxt *bp)
+{
+	return bp->num_tc ? bp->tx_nr_rings / bp->num_tc : bp->tx_nr_rings;
+}
+
 static int __bnxt_open_nic(struct bnxt *bp, bool irq_re_init, bool link_re_init)
 {
 	int rc = 0;
@@ -16338,7 +16349,7 @@ static void bnxt_trim_dflt_sh_rings(struct bnxt *bp)
 	bp->cp_nr_rings = min_t(int, bp->tx_nr_rings_per_tc, bp->rx_nr_rings);
 	bp->rx_nr_rings = bp->cp_nr_rings;
 	bp->tx_nr_rings_per_tc = bp->cp_nr_rings;
-	bp->tx_nr_rings = bp->tx_nr_rings_per_tc;
+	bp->tx_nr_rings = bnxt_tx_nr_rings(bp);
 }
 
 static int bnxt_set_dflt_rings(struct bnxt *bp, bool sh)
@@ -16370,7 +16381,7 @@ static int bnxt_set_dflt_rings(struct bnxt *bp, bool sh)
 		bnxt_trim_dflt_sh_rings(bp);
 	else
 		bp->cp_nr_rings = bp->tx_nr_rings_per_tc + bp->rx_nr_rings;
-	bp->tx_nr_rings = bp->tx_nr_rings_per_tc;
+	bp->tx_nr_rings = bnxt_tx_nr_rings(bp);
 
 	avail_msix = bnxt_get_max_func_irqs(bp) - bp->cp_nr_rings;
 	if (avail_msix >= BNXT_MIN_ROCE_CP_RINGS) {
@@ -16383,7 +16394,7 @@ static int bnxt_set_dflt_rings(struct bnxt *bp, bool sh)
 	rc = __bnxt_reserve_rings(bp);
 	if (rc && rc != -ENODEV)
 		netdev_warn(bp->dev, "Unable to reserve tx rings\n");
-	bp->tx_nr_rings_per_tc = bp->tx_nr_rings;
+	bp->tx_nr_rings_per_tc = bnxt_tx_nr_rings_per_tc(bp);
 	if (sh)
 		bnxt_trim_dflt_sh_rings(bp);
 
@@ -16392,7 +16403,7 @@ static int bnxt_set_dflt_rings(struct bnxt *bp, bool sh)
 		rc = __bnxt_reserve_rings(bp);
 		if (rc && rc != -ENODEV)
 			netdev_warn(bp->dev, "2nd rings reservation failed.\n");
-		bp->tx_nr_rings_per_tc = bp->tx_nr_rings;
+		bp->tx_nr_rings_per_tc = bnxt_tx_nr_rings_per_tc(bp);
 	}
 	if (BNXT_CHIP_TYPE_NITRO_A0(bp)) {
 		bp->rx_nr_rings++;
@@ -16426,7 +16437,7 @@ static int bnxt_init_dflt_ring_mode(struct bnxt *bp)
 	if (rc)
 		goto init_dflt_ring_err;
 
-	bp->tx_nr_rings_per_tc = bp->tx_nr_rings;
+	bp->tx_nr_rings_per_tc = bnxt_tx_nr_rings_per_tc(bp);
 
 	bnxt_set_dflt_rfs(bp);