IB/mlx5: Add support for DC target QP

A DC Target (DCT) QP is represented in the hardware as a unique object.
This object is created by CREATE_DCT command and destroyed by DESTROY_DCT
command. However, in the driver we describe it as a QP.

The hardware command that creates a DCT needs parameters that the verb
create_qp() does not provide. Those remaining parameters are provided
with the call to the verb modify_qp(). Therefore we delay the actual
creation of a DCT in the hardware until the stage of modify_qp() to RTR.

A support for query_qp() was added as well. It uses QUERY_DCT command to
retrieve the applicable fields.

Signed-off-by: Moni Shoua <monis@mellanox.com>
Reviewed-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
diff --git a/include/uapi/rdma/mlx5-abi.h b/include/uapi/rdma/mlx5-abi.h
index 83bde975..f6d319d 100644
--- a/include/uapi/rdma/mlx5-abi.h
+++ b/include/uapi/rdma/mlx5-abi.h
@@ -362,6 +362,11 @@ struct mlx5_ib_create_ah_resp {
 	__u8	reserved[6];
 };
 
+struct mlx5_ib_modify_qp_resp {
+	__u32	response_length;
+	__u32	dctn;
+};
+
 struct mlx5_ib_create_wq_resp {
 	__u32	response_length;
 	__u32	reserved;