[PATCH rdma-next] RDMA/mlx5: Enable Data-Direct with Relaxed Ordering

[PATCH rdma-next] RDMA/mlx5: Enable Data-Direct with Relaxed Ordering

[Leon Romanovsky]

From: Yishai Hadas <yishaih@nvidia.com>

Relaxed Ordering can improve performance in certain scenarios.

Enable it in the Data-Direct use case as well.

Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Reviewed-by: Gal Shalom <galshalom@Nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 drivers/infiniband/hw/mlx5/main.c    | 32 ++++++++++++++++++++++++++--
 drivers/infiniband/hw/mlx5/mlx5_ib.h |  2 ++
 drivers/infiniband/hw/mlx5/mr.c      |  8 +++----
 drivers/infiniband/hw/mlx5/umr.c     |  6 +++++-
 4 files changed, 41 insertions(+), 7 deletions(-)

diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c
index d456e4fde3e1..505349c68e79 100644
--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -3118,6 +3118,7 @@ mlx5_ib_create_data_direct_resources(struct mlx5_ib_dev *dev)
 {
 	int inlen = MLX5_ST_SZ_BYTES(create_mkey_in);
 	struct mlx5_core_dev *mdev = dev->mdev;
+	bool ro_supp = false;
 	void *mkc;
 	u32 mkey;
 	u32 pdn;
@@ -3146,14 +3147,37 @@ mlx5_ib_create_data_direct_resources(struct mlx5_ib_dev *dev)
 	MLX5_SET(mkc, mkc, length64, 1);
 	MLX5_SET(mkc, mkc, qpn, 0xffffff);
 	err = mlx5_core_create_mkey(mdev, &mkey, in, inlen);
-	kvfree(in);
 	if (err)
-		goto err;
+		goto err_mkey;
 
 	dev->ddr.mkey = mkey;
 	dev->ddr.pdn = pdn;
+
+	/* create another mkey with RO support */
+	if (MLX5_CAP_GEN(dev->mdev, relaxed_ordering_write)) {
+		MLX5_SET(mkc, mkc, relaxed_ordering_write, 1);
+		ro_supp = true;
+	}
+
+	if (MLX5_CAP_GEN(dev->mdev, relaxed_ordering_read)) {
+		MLX5_SET(mkc, mkc, relaxed_ordering_read, 1);
+		ro_supp = true;
+	}
+
+	if (ro_supp) {
+		err = mlx5_core_create_mkey(mdev, &mkey, in, inlen);
+		/* RO is defined as best effort */
+		if (!err) {
+			dev->ddr.mkey_ro = mkey;
+			dev->ddr.mkey_ro_valid = true;
+		}
+	}
+
+	kvfree(in);
 	return 0;
 
+err_mkey:
+	kvfree(in);
 err:
 	mlx5_core_dealloc_pd(mdev, pdn);
 	return err;
@@ -3162,6 +3186,10 @@ mlx5_ib_create_data_direct_resources(struct mlx5_ib_dev *dev)
 static void
 mlx5_ib_free_data_direct_resources(struct mlx5_ib_dev *dev)
 {
+
+	if (dev->ddr.mkey_ro_valid)
+		mlx5_core_destroy_mkey(dev->mdev, dev->ddr.mkey_ro);
+
 	mlx5_core_destroy_mkey(dev->mdev, dev->ddr.mkey);
 	mlx5_core_dealloc_pd(dev->mdev, dev->ddr.pdn);
 }
diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h
index 185d6e67e8ae..a6c83ce2f0ee 100644
--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -854,6 +854,8 @@ struct mlx5_ib_port_resources {
 struct mlx5_data_direct_resources {
 	u32 pdn;
 	u32 mkey;
+	u32 mkey_ro;
+	u8 mkey_ro_valid :1;
 };
 
 struct mlx5_ib_resources {
diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c
index 03729e137385..aded210dc0a8 100644
--- a/drivers/infiniband/hw/mlx5/mr.c
+++ b/drivers/infiniband/hw/mlx5/mr.c
@@ -1772,11 +1772,11 @@ reg_user_mr_dmabuf_by_data_direct(struct ib_pd *pd, u64 offset,
 		goto end;
 	}
 
-	/* The device's 'data direct mkey' was created without RO flags to
-	 * simplify things and allow for a single mkey per device.
-	 * Since RO is not a must, mask it out accordingly.
+	/* If no device's 'data direct mkey' with RO flags exists
+	 * mask it out accordingly.
 	 */
-	access_flags &= ~IB_ACCESS_RELAXED_ORDERING;
+	if (!dev->ddr.mkey_ro_valid)
+		access_flags &= ~IB_ACCESS_RELAXED_ORDERING;
 	crossed_mr = reg_user_mr_dmabuf(pd, &data_direct_dev->pdev->dev,
 					offset, length, virt_addr, fd,
 					access_flags, MLX5_MKC_ACCESS_MODE_KSM,
diff --git a/drivers/infiniband/hw/mlx5/umr.c b/drivers/infiniband/hw/mlx5/umr.c
index 7ef35cddce81..4e562e0dd9e1 100644
--- a/drivers/infiniband/hw/mlx5/umr.c
+++ b/drivers/infiniband/hw/mlx5/umr.c
@@ -761,7 +761,11 @@ _mlx5r_umr_update_mr_pas(struct mlx5_ib_mr *mr, unsigned int flags, bool dd,
 
 		if (dd) {
 			cur_ksm->va = cpu_to_be64(rdma_block_iter_dma_address(&biter));
-			cur_ksm->key = cpu_to_be32(dev->ddr.mkey);
+			if (mr->access_flags & IB_ACCESS_RELAXED_ORDERING &&
+			    dev->ddr.mkey_ro_valid)
+				cur_ksm->key = cpu_to_be32(dev->ddr.mkey_ro);
+			else
+				cur_ksm->key = cpu_to_be32(dev->ddr.mkey);
 			if (mr->umem->is_dmabuf &&
 			    (flags & MLX5_IB_UPD_XLT_ZAP)) {
 				cur_ksm->va = 0;
-- 
2.50.1

Re: [PATCH rdma-next] RDMA/mlx5: Enable Data-Direct with Relaxed Ordering

[Jason Gunthorpe]

On Wed, Aug 13, 2025 at 03:36:01PM +0300, Leon Romanovsky wrote:
> From: Yishai Hadas <yishaih@nvidia.com>
> 
> Relaxed Ordering can improve performance in certain scenarios.
> 
> Enable it in the Data-Direct use case as well.
> 
> Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
> Reviewed-by: Gal Shalom <galshalom@Nvidia.com>
> Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
> ---
>  drivers/infiniband/hw/mlx5/main.c    | 32 ++++++++++++++++++++++++++--
>  drivers/infiniband/hw/mlx5/mlx5_ib.h |  2 ++
>  drivers/infiniband/hw/mlx5/mr.c      |  8 +++----
>  drivers/infiniband/hw/mlx5/umr.c     |  6 +++++-
>  4 files changed, 41 insertions(+), 7 deletions(-)

Applied to for-next, thanks

Jason