RDMA/mlx5: Set user priority for DCT

Currently, the driver doesn't set the PCP-based priority for DCT, hence
DCT response packets are transmitted without user priority.

Fix it by setting user provided priority in the eth_prio field in the DCT
context, which in turn sets the value in the transmitted packet.

Fixes: 776a390 ("IB/mlx5: Add support for DC target QP")
Link: https://lore.kernel.org/r/5fd2d94a13f5742d8803c218927322257d53205c.1633512672.git.leonro@nvidia.com
Signed-off-by: Patrisious Haddad <phaddad@nvidia.com>
Reviewed-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/hw/mlx5/qp.c

@@ -4458,6 +4458,8 @@ static int mlx5_ib_modify_dct(struct ib_qp *ibqp, struct ib_qp_attr *attr,
 		MLX5_SET(dctc, dctc, mtu, attr->path_mtu);
 		MLX5_SET(dctc, dctc, my_addr_index, attr->ah_attr.grh.sgid_index);
 		MLX5_SET(dctc, dctc, hop_limit, attr->ah_attr.grh.hop_limit);
+		if (attr->ah_attr.type == RDMA_AH_ATTR_TYPE_ROCE)
+			MLX5_SET(dctc, dctc, eth_prio, attr->ah_attr.sl & 0x7);
 
 		err = mlx5_core_create_dct(dev, &qp->dct.mdct, qp->dct.in,
 					   MLX5_ST_SZ_BYTES(create_dct_in), out,