IB/core: Enable QP creation with a given source QP number

Enable QP creation with a given source QP number.
The created QP will use the source QPN as its wire QP number.

This comes as a pre-patch for downstream patches in this series to
allow user space applications to accelerate traffic which is typically
handled by IPoIB ULP.
Signed-off-by: Yishai Hadas <yishaih@mellanox.com>
Reviewed-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>

include/rdma/ib_verbs.h

@@ -1059,6 +1059,7 @@ enum ib_qp_create_flags {
 	/* FREE					= 1 << 7, */
 	IB_QP_CREATE_SCATTER_FCS		= 1 << 8,
 	IB_QP_CREATE_CVLAN_STRIPPING		= 1 << 9,
+	IB_QP_CREATE_SOURCE_QPN			= 1 << 10,
 	/* reserve bits 26-31 for low level drivers' internal use */
 	IB_QP_CREATE_RESERVED_START		= 1 << 26,
 	IB_QP_CREATE_RESERVED_END		= 1 << 31,
@@ -1086,6 +1087,7 @@ struct ib_qp_init_attr {
 	 */
 	u8			port_num;
 	struct ib_rwq_ind_table *rwq_ind_tbl;
+	u32			source_qpn;
 };
 
 struct ib_qp_open_attr {