Subject: [net 03/12] net/mlx5: Fix driver load with single msix vector

From: Saeed Mahameed <[email-masked]>
Date: Fri, 16 Jun 2023 13:01:10 -0700

From: Eli Cohen <[email-masked]>

When a PCI device has just one msix vector available, we want to share
this vector between async and completion events. Current code fails to
do that assuming it will always have at least one dedicated vector for
completion events. Fix this by detecting when the pool contains just a
single vector.

Fixes: 3354822cde5a ("net/mlx5: Use dynamic msix vectors allocation")
Signed-off-by: Eli Cohen <[email-masked]>
Reviewed-by: Shay Drory <[email-masked]>
Signed-off-by: Saeed Mahameed <[email-masked]>
---
 drivers/net/ethernet/mellanox/mlx5/core/pci_irq.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/pci_irq.c b/drivers/net/ethernet/mellanox/mlx5/core/pci_irq.c
index 843da89a9035..33b9359de53d 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/pci_irq.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/pci_irq.c
@@ -565,15 +565,21 @@ void mlx5_irqs_release_vectors(struct mlx5_irq **irqs, int nirqs)
 int mlx5_irqs_request_vectors(struct mlx5_core_dev *dev, u16 *cpus, int nirqs,
 			      struct mlx5_irq **irqs, struct cpu_rmap **rmap)
 {
+	struct mlx5_irq_table *table = mlx5_irq_table_get(dev);
+	struct mlx5_irq_pool *pool = table->pcif_pool;
 	struct irq_affinity_desc af_desc;
 	struct mlx5_irq *irq;
+	int offset = 1;
 	int i;
 
+	if (!pool->xa_num_irqs.max)
+		offset = 0;
+
 	af_desc.is_managed = false;
 	for (i = 0; i < nirqs; i++) {
 		cpumask_clear(&af_desc.mask);
 		cpumask_set_cpu(cpus[i], &af_desc.mask);
-		irq = mlx5_irq_request(dev, i + 1, &af_desc, rmap);
+		irq = mlx5_irq_request(dev, i + offset, &af_desc, rmap);
 		if (IS_ERR(irq))
 			break;
 		irqs[i] = irq;
-- 
2.40.1