IB/mlx4: Use multiple WQ blocks to post smaller send WQEs

ConnectX HCA supports shrinking WQEs, so that a single work request
can be made of multiple units of wqe_shift.  This way, WRs can differ
in size, and do not have to be a power of 2 in size, saving memory and
speeding up send WR posting.  Unfortunately, if we do this then the
wqe_index field in CQEs can't be used to look up the WR ID anymore, so
our implementation does this only if selective signaling is off.

Further, on 32-bit platforms, we can't use vmap() to make the QP
buffer virtually contigious. Thus we have to use constant-sized WRs to
make sure a WR is always fully within a single page-sized chunk.

Finally, we use WRs with the NOP opcode to avoid wrapping around the
queue buffer in the middle of posting a WR, and we set the
NoErrorCompletion bit to avoid getting completions with error for NOP
WRs.  However, NEC is only supported starting with firmware 2.2.232,
so we use constant-sized WRs for older firmware.  And, since MLX QPs
only support SEND, we use constant-sized WRs in this case.

When stamping during NOP posting, do stamping following setting of the
NOP WQE valid bit.

Signed-off-by: Michael S. Tsirkin <mst@dev.mellanox.co.il>
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 10 insertions, 2 deletions

diff --git a/drivers/infiniband/hw/mlx4/cq.c b/drivers/infiniband/hw/mlx4/cq.c
index 8ac7b973f870..7360bbafbe84 100644
--- a/drivers/infiniband/hw/mlx4/cq.c
+++ b/drivers/infiniband/hw/mlx4/cq.c
@@ -326,6 +326,12 @@ static int mlx4_ib_poll_one(struct mlx4_ib_cq *cq,
 	is_error = (cqe->owner_sr_opcode & MLX4_CQE_OPCODE_MASK) ==
 		MLX4_CQE_OPCODE_ERROR;
 
+	if (unlikely((cqe->owner_sr_opcode & MLX4_CQE_OPCODE_MASK) == MLX4_OPCODE_NOP &&
+		     is_send)) {
+		printk(KERN_WARNING "Completion for NOP opcode detected!\n");
+		return -EINVAL;
+	}
+
 	if (!*cur_qp ||
 	    (be32_to_cpu(cqe->my_qpn) & 0xffffff) != (*cur_qp)->mqp.qpn) {
 		/*
@@ -348,8 +354,10 @@ static int mlx4_ib_poll_one(struct mlx4_ib_cq *cq,
 
 	if (is_send) {
 		wq = &(*cur_qp)->sq;
-		wqe_ctr = be16_to_cpu(cqe->wqe_index);
-		wq->tail += (u16) (wqe_ctr - (u16) wq->tail);
+		if (!(*cur_qp)->sq_signal_bits) {
+			wqe_ctr = be16_to_cpu(cqe->wqe_index);
+			wq->tail += (u16) (wqe_ctr - (u16) wq->tail);
+		}
 		wc->wr_id = wq->wrid[wq->tail & (wq->wqe_cnt - 1)];
 		++wq->tail;
 	} else if ((*cur_qp)->ibqp.srq) {