[PATCH v3 05/17] IB/mlx5: Add function to read WQE from user-space

Haggai Eran
2014-12-11T15:04:14Z

Add a helper function mlx5_ib_read_user_wqe to read information from
user-space owned work queues. The function will be used in a later patch by
the page-fault handling code in mlx5_ib.

Signed-off-by: Haggai Eran <haggaie-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
---
drivers/infiniband/hw/mlx5/mlx5_ib.h | 2 +
drivers/infiniband/hw/mlx5/qp.c | 71 ++++++++++++++++++++++++++++++++++++
include/linux/mlx5/qp.h | 3 ++
3 files changed, 76 insertions(+)

diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h
index 53d19e6e69a4..14a0311eaa1c 100644
--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -503,6 +503,8 @@ int mlx5_ib_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
int mlx5_ib_post_recv(struct ib_qp *ibqp, struct ib_recv_wr *wr,
struct ib_recv_wr **bad_wr);
void *mlx5_get_send_wqe(struct mlx5_ib_qp *qp, int n);
+int mlx5_ib_read_user_wqe(struct mlx5_ib_qp *qp, int send, int wqe_index,
+ void *buffer, u32 length);
struct ib_cq *mlx5_ib_create_cq(struct ib_device *ibdev, int entries,
int vector, struct ib_ucontext *context,
struct ib_udata *udata);
diff --git a/drivers/infiniband/hw/mlx5/qp.c b/drivers/infiniband/hw/mlx5/qp.c
index 9bdcaf65f5e6..7ac9405aa44b 100644
--- a/drivers/infiniband/hw/mlx5/qp.c
+++ b/drivers/infiniband/hw/mlx5/qp.c
@@ -101,6 +101,77 @@ void *mlx5_get_send_wqe(struct mlx5_ib_qp *qp, int n)
return get_wqe(qp, qp->sq.offset + (n << MLX5_IB_SQ_STRIDE));
}

+/**
+ * mlx5_ib_read_user_wqe() - Copy a user-space WQE to kernel space.
+ *
+ * @qp: QP to copy from.
+ * @send: copy from the send queue when non-zero, use the receive queue
+ * otherwise.
+ * @wqe_index: index to start copying from. For send work queues, the
+ * wqe_index is in units of MLX5_SEND_WQE_BB.
+ * For receive work queue, it is the number of work queue
+ * element in the queue.
+ * @buffer: destination buffer.
+ * @length: maximum number of bytes to copy.
+ *
+ * Copies at least a single WQE, but may copy more data.
+ *
+ * Return: the number of bytes copied, or an error code.
+ */
+int mlx5_ib_read_user_wqe(struct mlx5_ib_qp *qp, int send, int wqe_index,
+ void *buffer, u32 length)
+{
+ struct ib_device *ibdev = qp->ibqp.device;
+ struct mlx5_ib_dev *dev = to_mdev(ibdev);
+ struct mlx5_ib_wq *wq = send ? &qp->sq : &qp->rq;
+ size_t offset;
+ size_t wq_end;
+ struct ib_umem *umem = qp->umem;
+ u32 first_copy_length;
+ int wqe_length;
+ int ret;
+
+ if (wq->wqe_cnt == 0) {
+ mlx5_ib_dbg(dev, "mlx5_ib_read_user_wqe for a QP with wqe_cnt == 0. qp_type: 0x%x\n",
+ qp->ibqp.qp_type);
+ return -EINVAL;
+ }
+
+ offset = wq->offset + ((wqe_index % wq->wqe_cnt) << wq->wqe_shift);
+ wq_end = wq->offset + (wq->wqe_cnt << wq->wqe_shift);
+
+ if (send && length < sizeof(struct mlx5_wqe_ctrl_seg))
+ return -EINVAL;
+
+ if (offset > umem->length ||
+ (send && offset + sizeof(struct mlx5_wqe_ctrl_seg) > umem->length))
+ return -EINVAL;
+
+ first_copy_length = min_t(u32, offset + length, wq_end) - offset;
+ ret = ib_umem_copy_from(buffer, umem, offset, first_copy_length);
+ if (ret)
+ return ret;
+
+ if (send) {
+ struct mlx5_wqe_ctrl_seg *ctrl = buffer;
+ int ds = be32_to_cpu(ctrl->qpn_ds) & MLX5_WQE_CTRL_DS_MASK;
+
+ wqe_length = ds * MLX5_WQE_DS_UNITS;
+ } else {
+ wqe_length = 1 << wq->wqe_shift;
+ }
+
+ if (wqe_length <= first_copy_length)
+ return first_copy_length;
+
+ ret = ib_umem_copy_from(buffer + first_copy_length, umem, wq->offset,
+ wqe_length - first_copy_length);
+ if (ret)
+ return ret;
+
+ return wqe_length;
+}
+
static void mlx5_ib_qp_event(struct mlx5_core_qp *qp, int type)
{
struct ib_qp *ibqp = &to_mibqp(qp)->ibqp;
diff --git a/include/linux/mlx5/qp.h b/include/linux/mlx5/qp.h
index 3fa075daeb1d..67f4b9660b06 100644
--- a/include/linux/mlx5/qp.h
+++ b/include/linux/mlx5/qp.h
@@ -189,6 +189,9 @@ struct mlx5_wqe_ctrl_seg {
__be32 imm;
};

+#define MLX5_WQE_CTRL_DS_MASK 0x3f
+#define MLX5_WQE_DS_UNITS 16
+
struct mlx5_wqe_xrc_seg {
__be32 xrc_srqn;
u8 rsvd[12];