[PATCH rdma-next] RDMA/mlx5: Fix vport loopback forcing for MPV device

[PATCH rdma-next] RDMA/mlx5: Fix vport loopback forcing for MPV device

[Leon Romanovsky]

From: Patrisious Haddad <phaddad@nvidia.com>

Previously loopback for MPV was supposed to be permanently enabled,
however other driver flows were able to over-ride that configuration
and disable it.

Add force_lb parameter that indicates that loopback should always be
enabled which prevents all other driver flows from disabling it.

Fixes: a9a9e68954f2 ("RDMA/mlx5: Fix vport loopback for MPV device")
Signed-off-by: Patrisious Haddad <phaddad@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 drivers/infiniband/hw/mlx5/main.c    | 19 +++++++++++++++----
 drivers/infiniband/hw/mlx5/mlx5_ib.h |  1 +
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c
index de5339170876..1fbc0351063d 100644
--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -1839,7 +1839,8 @@ static void deallocate_uars(struct mlx5_ib_dev *dev,
 }
 
 static int mlx5_ib_enable_lb_mp(struct mlx5_core_dev *master,
-				struct mlx5_core_dev *slave)
+				struct mlx5_core_dev *slave,
+				struct mlx5_ib_lb_state *lb_state)
 {
 	int err;
 
@@ -1851,6 +1852,7 @@ static int mlx5_ib_enable_lb_mp(struct mlx5_core_dev *master,
 	if (err)
 		goto out;
 
+	lb_state->force_enable = true;
 	return 0;
 
 out:
@@ -1859,16 +1861,22 @@ static int mlx5_ib_enable_lb_mp(struct mlx5_core_dev *master,
 }
 
 static void mlx5_ib_disable_lb_mp(struct mlx5_core_dev *master,
-				  struct mlx5_core_dev *slave)
+				  struct mlx5_core_dev *slave,
+				  struct mlx5_ib_lb_state *lb_state)
 {
 	mlx5_nic_vport_update_local_lb(slave, false);
 	mlx5_nic_vport_update_local_lb(master, false);
+
+	lb_state->force_enable = false;
 }
 
 int mlx5_ib_enable_lb(struct mlx5_ib_dev *dev, bool td, bool qp)
 {
 	int err = 0;
 
+	if (dev->lb.force_enable)
+		return 0;
+
 	mutex_lock(&dev->lb.mutex);
 	if (td)
 		dev->lb.user_td++;
@@ -1890,6 +1898,9 @@ int mlx5_ib_enable_lb(struct mlx5_ib_dev *dev, bool td, bool qp)
 
 void mlx5_ib_disable_lb(struct mlx5_ib_dev *dev, bool td, bool qp)
 {
+	if (dev->lb.force_enable)
+		return;
+
 	mutex_lock(&dev->lb.mutex);
 	if (td)
 		dev->lb.user_td--;
@@ -3597,7 +3608,7 @@ static void mlx5_ib_unbind_slave_port(struct mlx5_ib_dev *ibdev,
 
 	lockdep_assert_held(&mlx5_ib_multiport_mutex);
 
-	mlx5_ib_disable_lb_mp(ibdev->mdev, mpi->mdev);
+	mlx5_ib_disable_lb_mp(ibdev->mdev, mpi->mdev, &ibdev->lb);
 
 	mlx5_core_mp_event_replay(ibdev->mdev,
 				  MLX5_DRIVER_EVENT_AFFILIATION_REMOVED,
@@ -3694,7 +3705,7 @@ static bool mlx5_ib_bind_slave_port(struct mlx5_ib_dev *ibdev,
 				  MLX5_DRIVER_EVENT_AFFILIATION_DONE,
 				  &key);
 
-	err = mlx5_ib_enable_lb_mp(ibdev->mdev, mpi->mdev);
+	err = mlx5_ib_enable_lb_mp(ibdev->mdev, mpi->mdev, &ibdev->lb);
 	if (err)
 		goto unbind;
 
diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h
index a6c83ce2f0ee..4fc2c0ca2af3 100644
--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -1111,6 +1111,7 @@ struct mlx5_ib_lb_state {
 	u32			user_td;
 	int			qps;
 	bool			enabled;
+	bool			force_enable;
 };
 
 struct mlx5_ib_pf_eq {
-- 
2.50.1

Re: [PATCH rdma-next] RDMA/mlx5: Fix vport loopback forcing for MPV device

[Jason Gunthorpe]

On Wed, Aug 13, 2025 at 03:41:19PM +0300, Leon Romanovsky wrote:
> From: Patrisious Haddad <phaddad@nvidia.com>
> 
> Previously loopback for MPV was supposed to be permanently enabled,
> however other driver flows were able to over-ride that configuration
> and disable it.
> 
> Add force_lb parameter that indicates that loopback should always be
> enabled which prevents all other driver flows from disabling it.
> 
> Fixes: a9a9e68954f2 ("RDMA/mlx5: Fix vport loopback for MPV device")
> Signed-off-by: Patrisious Haddad <phaddad@nvidia.com>
> Reviewed-by: Mark Bloch <mbloch@nvidia.com>
> Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
> ---
>  drivers/infiniband/hw/mlx5/main.c    | 19 +++++++++++++++----
>  drivers/infiniband/hw/mlx5/mlx5_ib.h |  1 +
>  2 files changed, 16 insertions(+), 4 deletions(-)

Applied to for-next, thanks

Jason