[PATCH rdma-next] RDMA/mlx5: Deprecate latency-sensitive QPs feature

From: Michael Guralnik <[email protected]>

New HW no longer implements a separate class for latency-sensitive QPs and
advertises this by a new cap bit.
REG_UMR is the only QP that used this feature, so gate its usage of the
feature on this cap.

Signed-off-by: Michael Guralnik <[email protected]>
Reviewed-by: Patrisious Haddad <[email protected]>
Signed-off-by: Edward Srouji <[email protected]>
---
 drivers/infiniband/hw/mlx5/main.c |  6 +++++-
 drivers/infiniband/hw/mlx5/qp.c   | 12 +++++++-----
 include/linux/mlx5/mlx5_ifc.h     |  3 ++-
 3 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c
index d65ebdef28234fe91ad4c24a5ded2d3af8bc646e..a0f5341f40ff1c0414939dba50301f0255825065 100644
--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -4950,6 +4950,9 @@ static int mlx5_ib_stage_bfrag_init(struct mlx5_ib_dev *dev)
 	if (err)
 		return err;
 
+	if (MLX5_CAP_GEN(dev->mdev, qp_latency_sensitive_disable))
+		return 0;
+
 	err = mlx5_alloc_bfreg(dev->mdev, &dev->fp_bfreg, false, true);
 	if (err)
 		mlx5_free_bfreg(dev->mdev, &dev->bfreg);
@@ -4959,7 +4962,8 @@ static int mlx5_ib_stage_bfrag_init(struct mlx5_ib_dev *dev)
 
 static void mlx5_ib_stage_bfrag_cleanup(struct mlx5_ib_dev *dev)
 {
-	mlx5_free_bfreg(dev->mdev, &dev->fp_bfreg);
+	if (!MLX5_CAP_GEN(dev->mdev, qp_latency_sensitive_disable))
+		mlx5_free_bfreg(dev->mdev, &dev->fp_bfreg);
 	mlx5_free_bfreg(dev->mdev, &dev->bfreg);
 }
 
diff --git a/drivers/infiniband/hw/mlx5/qp.c b/drivers/infiniband/hw/mlx5/qp.c
index 7ff02d89c31d5b4db4c94453efafc0fce212acea..9253402ed645c9985eed098d3b21bea638028218 100644
--- a/drivers/infiniband/hw/mlx5/qp.c
+++ b/drivers/infiniband/hw/mlx5/qp.c
@@ -1123,7 +1123,8 @@ static int _create_kernel_qp(struct mlx5_ib_dev *dev,
 	void *qpc;
 	int err;
 
-	if (init_attr->qp_type == MLX5_IB_QPT_REG_UMR)
+	if (init_attr->qp_type == MLX5_IB_QPT_REG_UMR &&
+	    !MLX5_CAP_GEN(dev->mdev, qp_latency_sensitive_disable))
 		qp->bf.bfreg = &dev->fp_bfreg;
 	else
 		qp->bf.bfreg = &dev->bfreg;
@@ -2509,11 +2510,12 @@ static int create_kernel_qp(struct mlx5_ib_dev *dev, struct ib_pd *pd,
 	MLX5_SET(qpc, qpc, st, mlx5_st);
 	MLX5_SET(qpc, qpc, pm_state, MLX5_QP_PM_MIGRATED);
 
-	if (attr->qp_type != MLX5_IB_QPT_REG_UMR)
+	if (attr->qp_type == MLX5_IB_QPT_REG_UMR) {
+		if (!MLX5_CAP_GEN(dev->mdev, qp_latency_sensitive_disable))
+			MLX5_SET(qpc, qpc, latency_sensitive, 1);
+	} else {
 		MLX5_SET(qpc, qpc, pd, to_mpd(pd ? pd : devr->p0)->pdn);
-	else
-		MLX5_SET(qpc, qpc, latency_sensitive, 1);
-
+	}
 
 	if (qp->flags & IB_QP_CREATE_BLOCK_MULTICAST_LOOPBACK)
 		MLX5_SET(qpc, qpc, block_lb_mc, 1);
diff --git a/include/linux/mlx5/mlx5_ifc.h b/include/linux/mlx5/mlx5_ifc.h
index 695c86ee6d7a3f15945fe7af092f63d9121da47a..28582c4d94d4335283009595f6a278c4d17c7eaa 100644
--- a/include/linux/mlx5/mlx5_ifc.h
+++ b/include/linux/mlx5/mlx5_ifc.h
@@ -2005,7 +2005,8 @@ struct mlx5_ifc_cmd_hca_cap_bits {
 	u8         log_max_stride_sz_rq[0x5];
 	u8         reserved_at_3a8[0x3];
 	u8         log_min_stride_sz_rq[0x5];
-	u8         reserved_at_3b0[0x3];
+	u8         reserved_at_3b0[0x2];
+	u8         qp_latency_sensitive_disable[0x1];
 	u8         log_max_stride_sz_sq[0x5];
 	u8         reserved_at_3b8[0x3];
 	u8         log_min_stride_sz_sq[0x5];

---
base-commit: 9b66c9af7172ffcf727214fa0ebe9a5e1ed6eb16
change-id: 20260723-deprecate-lat-qps-ca1942227499

Best regards,
-- 
Edward Srouji <[email protected]>