mlx4_core: Add QP range reservation support

To allow allocating an aligned range of consecutive QP numbers, add an
interface to reserve an aligned range of QP numbers and have the QP
allocation function always take a QP number.

This will be used for RSS support in the mlx4_en Ethernet driver and
also potentially by IPoIB RSS support.

Signed-off-by: Yevgeny Petrilin <yevgenyp@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/mlx4/qp.c

@@ -451,6 +451,7 @@ static int create_qp_common(struct mlx4_ib_dev *dev, struct ib_pd *pd,
 			    struct ib_qp_init_attr *init_attr,
 			    struct ib_udata *udata, int sqpn, struct mlx4_ib_qp *qp)
 {
+	int qpn;
 	int err;
 
 	mutex_init(&qp->mutex);
@@ -545,9 +546,17 @@ static int create_qp_common(struct mlx4_ib_dev *dev, struct ib_pd *pd,
 		}
 	}
 
-	err = mlx4_qp_alloc(dev->dev, sqpn, &qp->mqp);
+	if (sqpn) {
+		qpn = sqpn;
+	} else {
+		err = mlx4_qp_reserve_range(dev->dev, 1, 1, &qpn);
+		if (err)
+			goto err_wrid;
+	}
+
+	err = mlx4_qp_alloc(dev->dev, qpn, &qp->mqp);
 	if (err)
-		goto err_wrid;
+		goto err_qpn;
 
 	/*
 	 * Hardware wants QPN written in big-endian order (after
@@ -560,6 +569,10 @@ static int create_qp_common(struct mlx4_ib_dev *dev, struct ib_pd *pd,
 
 	return 0;
 
+err_qpn:
+	if (!sqpn)
+		mlx4_qp_release_range(dev->dev, qpn, 1);
+
 err_wrid:
 	if (pd->uobject) {
 		if (!init_attr->srq)
@@ -655,6 +668,10 @@ static void destroy_qp_common(struct mlx4_ib_dev *dev, struct mlx4_ib_qp *qp,
 	mlx4_ib_unlock_cqs(send_cq, recv_cq);
 
 	mlx4_qp_free(dev->dev, &qp->mqp);
+
+	if (!is_sqp(dev, qp))
+		mlx4_qp_release_range(dev->dev, qp->mqp.qpn, 1);
+
 	mlx4_mtt_cleanup(dev->dev, &qp->mtt);
 
 	if (is_user) {