* [PATCH rdma-next] RDMA/mlx5: Deprecate latency-sensitive QPs feature
@ 2026-07-23 15:01 Edward Srouji
2026-07-26 7:37 ` Leon Romanovsky
0 siblings, 1 reply; 2+ messages in thread
From: Edward Srouji @ 2026-07-23 15:01 UTC (permalink / raw)
To: Leon Romanovsky, Jason Gunthorpe, Saeed Mahameed, Tariq Toukan,
Mark Bloch
Cc: linux-rdma, linux-kernel, netdev, Michael Guralnik,
Patrisious Haddad, Edward Srouji
From: Michael Guralnik <michaelgur@nvidia.com>
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 <michaelgur@nvidia.com>
Reviewed-by: Patrisious Haddad <phaddad@nvidia.com>
Signed-off-by: Edward Srouji <edwards@nvidia.com>
---
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 <edwards@nvidia.com>
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH rdma-next] RDMA/mlx5: Deprecate latency-sensitive QPs feature
2026-07-23 15:01 [PATCH rdma-next] RDMA/mlx5: Deprecate latency-sensitive QPs feature Edward Srouji
@ 2026-07-26 7:37 ` Leon Romanovsky
0 siblings, 0 replies; 2+ messages in thread
From: Leon Romanovsky @ 2026-07-26 7:37 UTC (permalink / raw)
To: Edward Srouji
Cc: Jason Gunthorpe, Saeed Mahameed, Tariq Toukan, Mark Bloch,
linux-rdma, linux-kernel, netdev, Michael Guralnik,
Patrisious Haddad
On Thu, Jul 23, 2026 at 06:01:23PM +0300, Edward Srouji wrote:
> From: Michael Guralnik <michaelgur@nvidia.com>
>
> 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 <michaelgur@nvidia.com>
> Reviewed-by: Patrisious Haddad <phaddad@nvidia.com>
> Signed-off-by: Edward Srouji <edwards@nvidia.com>
> ---
> 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];
This change should be split into a separate commit.
Thanks
> 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 <edwards@nvidia.com>
>
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