IB/mlx4: Remove limitation on LSO header size

Current code has a limitation: an LSO header is not allowed to cross a
64 byte boundary.  This patch removes this limitation by setting the
WQE RR for large headers thus allowing LSO headers of any size.  The
extra buffer reserved for MLX4_IB_QP_LSO QPs has been doubled, from 64
to 128 bytes, assuming this is reasonable upper limit for header
length.  Also, this patch will cause IB_DEVICE_UD_TSO to be set only
for HCA FW versions that set MLX4_DEV_CAP_FLAG_BLH; e.g. FW version
2.6.000 and higher.
Signed-off-by: Eli Cohen <eli@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/mlx4/main.c

@@ -103,7 +103,7 @@ static int mlx4_ib_query_device(struct ib_device *ibdev,
 		props->device_cap_flags |= IB_DEVICE_UD_AV_PORT_ENFORCE;
 	if (dev->dev->caps.flags & MLX4_DEV_CAP_FLAG_IPOIB_CSUM)
 		props->device_cap_flags |= IB_DEVICE_UD_IP_CSUM;
-	if (dev->dev->caps.max_gso_sz)
+	if (dev->dev->caps.max_gso_sz && dev->dev->caps.flags & MLX4_DEV_CAP_FLAG_BLH)
 		props->device_cap_flags |= IB_DEVICE_UD_TSO;
 	if (dev->dev->caps.bmme_flags & MLX4_BMME_FLAG_RESERVED_LKEY)
 		props->device_cap_flags |= IB_DEVICE_LOCAL_DMA_LKEY;

drivers/infiniband/hw/mlx4/qp.c

@@ -54,7 +54,8 @@ enum {
 	/*
 	 * Largest possible UD header: send with GRH and immediate data.
 	 */
-	MLX4_IB_UD_HEADER_SIZE		= 72
+	MLX4_IB_UD_HEADER_SIZE		= 72,
+	MLX4_IB_LSO_HEADER_SPARE	= 128,
 };
 
 struct mlx4_ib_sqp {
@@ -67,7 +68,8 @@ struct mlx4_ib_sqp {
 };
 
 enum {
-	MLX4_IB_MIN_SQ_STRIDE = 6
+	MLX4_IB_MIN_SQ_STRIDE	= 6,
+	MLX4_IB_CACHE_LINE_SIZE	= 64,
 };
 
 static const __be32 mlx4_ib_opcode[] = {
@@ -261,7 +263,7 @@ static int send_wqe_overhead(enum ib_qp_type type, u32 flags)
 	case IB_QPT_UD:
 		return sizeof (struct mlx4_wqe_ctrl_seg) +
 			sizeof (struct mlx4_wqe_datagram_seg) +
-			((flags & MLX4_IB_QP_LSO) ? 64 : 0);
+			((flags & MLX4_IB_QP_LSO) ? MLX4_IB_LSO_HEADER_SPARE : 0);
 	case IB_QPT_UC:
 		return sizeof (struct mlx4_wqe_ctrl_seg) +
 			sizeof (struct mlx4_wqe_raddr_seg);
@@ -1466,16 +1468,12 @@ static void __set_data_seg(struct mlx4_wqe_data_seg *dseg, struct ib_sge *sg)
 
 static int build_lso_seg(struct mlx4_wqe_lso_seg *wqe, struct ib_send_wr *wr,
 			 struct mlx4_ib_qp *qp, unsigned *lso_seg_len,
-			 __be32 *lso_hdr_sz)
+			 __be32 *lso_hdr_sz, __be32 *blh)
 {
 	unsigned halign = ALIGN(sizeof *wqe + wr->wr.ud.hlen, 16);
 
-	/*
-	 * This is a temporary limitation and will be removed in
-	 * a forthcoming FW release:
-	 */
-	if (unlikely(halign > 64))
-		return -EINVAL;
+	if (unlikely(halign > MLX4_IB_CACHE_LINE_SIZE))
+		*blh = cpu_to_be32(1 << 6);
 
 	if (unlikely(!(qp->flags & MLX4_IB_QP_LSO) &&
 		     wr->num_sge > qp->sq.max_gs - (halign >> 4)))
@@ -1521,6 +1519,7 @@ int mlx4_ib_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
 	__be32 dummy;
 	__be32 *lso_wqe;
 	__be32 uninitialized_var(lso_hdr_sz);
+	__be32 blh;
 	int i;
 
 	spin_lock_irqsave(&qp->sq.lock, flags);
@@ -1529,6 +1528,7 @@ int mlx4_ib_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
 
 	for (nreq = 0; wr; ++nreq, wr = wr->next) {
 		lso_wqe = &dummy;
+		blh = 0;
 
 		if (mlx4_wq_overflow(&qp->sq, nreq, qp->ibqp.send_cq)) {
 			err = -ENOMEM;
@@ -1615,7 +1615,7 @@ int mlx4_ib_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
 			size += sizeof (struct mlx4_wqe_datagram_seg) / 16;
 
 			if (wr->opcode == IB_WR_LSO) {
-				err = build_lso_seg(wqe, wr, qp, &seglen, &lso_hdr_sz);
+				err = build_lso_seg(wqe, wr, qp, &seglen, &lso_hdr_sz, &blh);
 				if (unlikely(err)) {
 					*bad_wr = wr;
 					goto out;
@@ -1686,7 +1686,7 @@ int mlx4_ib_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
 		}
 
 		ctrl->owner_opcode = mlx4_ib_opcode[wr->opcode] |
-			(ind & qp->sq.wqe_cnt ? cpu_to_be32(1 << 31) : 0);
+			(ind & qp->sq.wqe_cnt ? cpu_to_be32(1 << 31) : 0) | blh;
 
 		stamp = ind + qp->sq_spare_wqes;
 		ind += DIV_ROUND_UP(size * 16, 1U << qp->sq.wqe_shift);

drivers/net/mlx4/fw.c

@@ -90,6 +90,7 @@ static void dump_dev_cap_flags(struct mlx4_dev *dev, u32 flags)
 		[ 9] = "Q_Key violation counter",
 		[10] = "VMM",
 		[12] = "DPDP",
+		[15] = "Big LSO headers",
 		[16] = "MW support",
 		[17] = "APM support",
 		[18] = "Atomic ops support",

include/linux/mlx4/device.h

@@ -61,6 +61,7 @@ enum {
 	MLX4_DEV_CAP_FLAG_BAD_PKEY_CNTR	= 1 <<  8,
 	MLX4_DEV_CAP_FLAG_BAD_QKEY_CNTR	= 1 <<  9,
 	MLX4_DEV_CAP_FLAG_DPDP		= 1 << 12,
+	MLX4_DEV_CAP_FLAG_BLH		= 1 << 15,
 	MLX4_DEV_CAP_FLAG_MEM_WINDOW	= 1 << 16,
 	MLX4_DEV_CAP_FLAG_APM		= 1 << 17,
 	MLX4_DEV_CAP_FLAG_ATOMIC	= 1 << 18,