netdev - [PATCH net-next 9/9] bnxt_en: Support dynamic MSIX

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Message-ID: <20240713234339.70293-10-michael.chan@broadcom.com>
Date: Sat, 13 Jul 2024 16:43:39 -0700
From: Michael Chan <michael.chan@...adcom.com>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	pavan.chebbi@...adcom.com,
	andrew.gospodarek@...adcom.com,
	Hongguang Gao <hongguang.gao@...adcom.com>,
	Somnath Kotur <somnath.kotur@...adcom.com>
Subject: [PATCH net-next 9/9] bnxt_en: Support dynamic MSIX

A range of MSIX vectors are allocated at initializtion for the number
needed for RocE and L2.  During run-time, if the user increases or
decreases the number of L2 rings, all the MSIX vectors have to be
freed and a new range has to be allocated.  This is not optimal and
causes disruptions to RoCE traffic every time there is a change in L2
MSIX.

If the system supports dynamic MSIX allocations, use dynamic
allocation to add new L2 MSIX vectors or free unneeded L2 MSIX
vectors.  RoCE traffic is not affected using this scheme.

Reviewed-by: Hongguang Gao <hongguang.gao@...adcom.com>
Reviewed-by: Somnath Kotur <somnath.kotur@...adcom.com>
Signed-off-by: Michael Chan <michael.chan@...adcom.com>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c | 57 +++++++++++++++++++++--
 1 file changed, 54 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 7483ea246c9d..c987a9dd969c 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -10597,6 +10597,43 @@ static void bnxt_setup_msix(struct bnxt *bp)
 
 static int bnxt_init_int_mode(struct bnxt *bp);
 
+static int bnxt_add_msix(struct bnxt *bp, int total)
+{
+	int i;
+
+	if (bp->total_irqs >= total)
+		return total;
+
+	for (i = bp->total_irqs; i < total; i++) {
+		struct msi_map map;
+
+		map = pci_msix_alloc_irq_at(bp->pdev, i, NULL);
+		if (map.index < 0)
+			break;
+		bp->irq_tbl[i].vector = map.virq;
+		bp->total_irqs++;
+	}
+	return bp->total_irqs;
+}
+
+static int bnxt_trim_msix(struct bnxt *bp, int total)
+{
+	int i;
+
+	if (bp->total_irqs <= total)
+		return total;
+
+	for (i = bp->total_irqs; i > total; i--) {
+		struct msi_map map;
+
+		map.index = i - 1;
+		map.virq = bp->irq_tbl[i - 1].vector;
+		pci_msix_free_irq(bp->pdev, map);
+		bp->total_irqs--;
+	}
+	return bp->total_irqs;
+}
+
 static int bnxt_setup_int_mode(struct bnxt *bp)
 {
 	int rc;
@@ -10763,6 +10800,7 @@ static void bnxt_clear_int_mode(struct bnxt *bp)
 int bnxt_reserve_rings(struct bnxt *bp, bool irq_re_init)
 {
 	bool irq_cleared = false;
+	bool irq_change = false;
 	int tcs = bp->num_tc;
 	int irqs_required;
 	int rc;
@@ -10781,15 +10819,28 @@ int bnxt_reserve_rings(struct bnxt *bp, bool irq_re_init)
 	}
 
 	if (irq_re_init && BNXT_NEW_RM(bp) && irqs_required != bp->total_irqs) {
-		bnxt_ulp_irq_stop(bp);
-		bnxt_clear_int_mode(bp);
-		irq_cleared = true;
+		irq_change = true;
+		if (!pci_msix_can_alloc_dyn(bp->pdev)) {
+			bnxt_ulp_irq_stop(bp);
+			bnxt_clear_int_mode(bp);
+			irq_cleared = true;
+		}
 	}
 	rc = __bnxt_reserve_rings(bp);
 	if (irq_cleared) {
 		if (!rc)
 			rc = bnxt_init_int_mode(bp);
 		bnxt_ulp_irq_restart(bp, rc);
+	} else if (irq_change && !rc) {
+		int total;
+
+		if (irqs_required > bp->total_irqs)
+			total = bnxt_add_msix(bp, irqs_required);
+		else
+			total = bnxt_trim_msix(bp, irqs_required);
+
+		if (total != irqs_required)
+			rc = -ENOSPC;
 	}
 	if (rc) {
 		netdev_err(bp->dev, "ring reservation/IRQ init failure rc: %d\n", rc);
-- 
2.30.1


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