diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h
index d2b9737baa36..8dc6cd818baf 100644
--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -165,6 +165,18 @@ struct mlx5_ib_flow_db {
 #define MLX5_IB_QPT_REG_UMR	IB_QPT_RESERVED1
 #define MLX5_IB_WR_UMR		IB_WR_RESERVED1
 
+/* Private QP creation flags to be passed in ib_qp_init_attr.create_flags.
+ *
+ * These flags are intended for internal use by the mlx5_ib driver, and they
+ * rely on the range reserved for that use in the ib_qp_create_flags enum.
+ */
+
+/* Create a UD QP whose source QP number is 1 */
+static inline enum ib_qp_create_flags mlx5_ib_create_qp_sqpn_qp1(void)
+{
+	return IB_QP_CREATE_RESERVED_START;
+}
+
 struct wr_list {
 	u16	opcode;
 	u16	next;
@@ -330,6 +342,8 @@ enum mlx5_ib_qp_flags {
 	MLX5_IB_QP_CROSS_CHANNEL		= 1 << 2,
 	MLX5_IB_QP_MANAGED_SEND			= 1 << 3,
 	MLX5_IB_QP_MANAGED_RECV			= 1 << 4,
+	/* QP uses 1 as its source QP number */
+	MLX5_IB_QP_SQPN_QP1			= 1 << 5,
 };
 
 struct mlx5_umr_wr {
diff --git a/drivers/infiniband/hw/mlx5/qp.c b/drivers/infiniband/hw/mlx5/qp.c
index 34cb8e87c7b8..7cf789d1aa29 100644
--- a/drivers/infiniband/hw/mlx5/qp.c
+++ b/drivers/infiniband/hw/mlx5/qp.c
@@ -783,7 +783,9 @@ static int create_kernel_qp(struct mlx5_ib_dev *dev,
 	int err;
 
 	uuari = &dev->mdev->priv.uuari;
-	if (init_attr->create_flags & ~(IB_QP_CREATE_SIGNATURE_EN | IB_QP_CREATE_BLOCK_MULTICAST_LOOPBACK))
+	if (init_attr->create_flags & ~(IB_QP_CREATE_SIGNATURE_EN |
+					IB_QP_CREATE_BLOCK_MULTICAST_LOOPBACK |
+					mlx5_ib_create_qp_sqpn_qp1()))
 		return -EINVAL;
 
 	if (init_attr->qp_type == MLX5_IB_QPT_REG_UMR)
@@ -828,6 +830,11 @@ static int create_kernel_qp(struct mlx5_ib_dev *dev,
 	(*in)->ctx.params1 |= cpu_to_be32(1 << 11);
 	(*in)->ctx.sq_crq_size |= cpu_to_be16(1 << 4);
 
+	if (init_attr->create_flags & mlx5_ib_create_qp_sqpn_qp1()) {
+		(*in)->ctx.deth_sqpn = cpu_to_be32(1);
+		qp->flags |= MLX5_IB_QP_SQPN_QP1;
+	}
+
 	mlx5_fill_page_array(&qp->buf, (*in)->pas);
 
 	err = mlx5_db_alloc(dev->mdev, &qp->db);
@@ -1271,6 +1278,11 @@ static int create_qp_common(struct mlx5_ib_dev *dev, struct ib_pd *pd,
 					    ucmd.sq_wqe_count, max_wqes);
 				return -EINVAL;
 			}
+			if (init_attr->create_flags &
+			    mlx5_ib_create_qp_sqpn_qp1()) {
+				mlx5_ib_dbg(dev, "user-space is not allowed to create UD QPs spoofing as QP1\n");
+				return -EINVAL;
+			}
 			err = create_user_qp(dev, pd, qp, udata, init_attr, &in,
 					     &resp, &inlen, base);
 			if (err)
@@ -2284,6 +2296,8 @@ static int __mlx5_ib_modify_qp(struct ib_qp *ibqp,
 	if (!ibqp->uobject && cur_state == IB_QPS_RESET && new_state == IB_QPS_INIT)
 		context->sq_crq_size |= cpu_to_be16(1 << 4);
 
+	if (qp->flags & MLX5_IB_QP_SQPN_QP1)
+		context->deth_sqpn = cpu_to_be32(1);
 
 	mlx5_cur = to_mlx5_state(cur_state);
 	mlx5_new = to_mlx5_state(new_state);
@@ -3874,6 +3888,8 @@ int mlx5_ib_query_qp(struct ib_qp *ibqp, struct ib_qp_attr *qp_attr,
 		qp_init_attr->create_flags |= IB_QP_CREATE_MANAGED_SEND;
 	if (qp->flags & MLX5_IB_QP_MANAGED_RECV)
 		qp_init_attr->create_flags |= IB_QP_CREATE_MANAGED_RECV;
+	if (qp->flags & MLX5_IB_QP_SQPN_QP1)
+		qp_init_attr->create_flags |= mlx5_ib_create_qp_sqpn_qp1();
 
 	qp_init_attr->sq_sig_type = qp->sq_signal_bits & MLX5_WQE_CTRL_CQ_UPDATE ?
 		IB_SIGNAL_ALL_WR : IB_SIGNAL_REQ_WR;
diff --git a/include/linux/mlx5/mlx5_ifc.h b/include/linux/mlx5/mlx5_ifc.h
index 51f1e540fc2b..2b35ee445cc3 100644
--- a/include/linux/mlx5/mlx5_ifc.h
+++ b/include/linux/mlx5/mlx5_ifc.h
@@ -770,7 +770,8 @@ struct mlx5_ifc_cmd_hca_cap_bits {
 	u8         reserved_at_22e[0x7];
 	u8         qkv[0x1];
 	u8         pkv[0x1];
-	u8         reserved_at_237[0x4];
+	u8         set_deth_sqpn[0x1];
+	u8         reserved_at_239[0x3];
 	u8         xrc[0x1];
 	u8         ud[0x1];
 	u8         uc[0x1];
diff --git a/include/linux/mlx5/qp.h b/include/linux/mlx5/qp.h
index 5b8c89ffaa58..e5bbcf06de95 100644
--- a/include/linux/mlx5/qp.h
+++ b/include/linux/mlx5/qp.h
@@ -499,7 +499,8 @@ struct mlx5_qp_context {
 	u8			reserved2[4];
 	__be32			next_send_psn;
 	__be32			cqn_send;
-	u8			reserved3[8];
+	__be32			deth_sqpn;
+	u8			reserved3[4];
 	__be32			last_acked_psn;
 	__be32			ssn;
 	__be32			params2;
