2 files changed, 12 insertions, 1 deletions

diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c
index 5acf346e048e..049754f6e638 100644
--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -530,7 +530,7 @@ static int mlx5_ib_query_device(struct ib_device *ibdev,
                      sizeof(struct mlx5_wqe_ctrl_seg)) /
                      sizeof(struct mlx5_wqe_data_seg);
         props->max_sge = min(max_rq_sg, max_sq_sg);
-        props->max_sge_rd = props->max_sge;
+        props->max_sge_rd          = MLX5_MAX_SGE_RD;
         props->max_cq              = 1 << MLX5_CAP_GEN(mdev, log_max_cq);
         props->max_cqe = (1 << MLX5_CAP_GEN(mdev, log_max_cq_sz)) - 1;
         props->max_mr              = 1 << MLX5_CAP_GEN(mdev, log_max_mkey);
diff --git a/include/linux/mlx5/device.h b/include/linux/mlx5/device.h
index 8156e3c9239c..b3575f392492 100644
--- a/include/linux/mlx5/device.h
+++ b/include/linux/mlx5/device.h
@@ -392,6 +392,17 @@ enum {
         MLX5_CAP_OFF_CMDIF_CSUM         = 46,
 };
 
+enum {
+        /*
+         * Max wqe size for rdma read is 512 bytes, so this
+         * limits our max_sge_rd as the wqe needs to fit:
+         * - ctrl segment (16 bytes)
+         * - rdma segment (16 bytes)
+         * - scatter elements (16 bytes each)
+         */
+        MLX5_MAX_SGE_RD = (512 - 16 - 16) / 16
+};
+
 struct mlx5_inbox_hdr {
         __be16          opcode;
         u8              rsvd[4];