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  4. mlx5dv_create_qp(3)

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mlx5dv_create_qp(3) mlx5 Programmer's Manual mlx5dv_create_qp(3)

NAME

mlx5dv_create_qp - creates a queue pair (QP)

SYNOPSIS

#include <infiniband/mlx5dv.h>
struct ibv_qp *mlx5dv_create_qp(struct ibv_context         *context,
                                struct ibv_qp_init_attr_ex *qp_attr,
                                struct mlx5dv_qp_init_attr *mlx5_qp_attr)

DESCRIPTION

mlx5dv_create_qp() creates a queue pair (QP) with specific driver properties.

ARGUMENTS

Please see ibv_create_qp_ex(3) man page for context and qp_attr.

mlx5_qp_attr

struct mlx5dv_qp_init_attr {
    uint64_t comp_mask;
    uint32_t create_flags;
    struct mlx5dv_dc_init_attr  dc_init_attr;
    uint64_t send_ops_flags;
};
Bitmask specifying what fields in the structure are valid: MLX5DV_QP_INIT_ATTR_MASK_QP_CREATE_FLAGS: valid values in create_flags MLX5DV_QP_INIT_ATTR_MASK_DC: valid values in dc_init_attr MLX5DV_QP_INIT_ATTR_MASK_SEND_OPS_FLAGS: valid values in send_ops_flags
A bitwise OR of the various values described below.

MLX5DV_QP_CREATE_TUNNEL_OFFLOADS: Enable offloading such as checksum and LRO for incoming tunneling traffic.

MLX5DV_QP_CREATE_TIR_ALLOW_SELF_LOOPBACK_UC: Allow receiving loopback unicast traffic.

MLX5DV_QP_CREATE_TIR_ALLOW_SELF_LOOPBACK_MC: Allow receiving loopback multicast traffic.

MLX5DV_QP_CREATE_DISABLE_SCATTER_TO_CQE: Disable scatter to CQE feature which is enabled by default.

MLX5DV_QP_CREATE_ALLOW_SCATTER_TO_CQE: Allow scatter to CQE for requester even if the qp was not configured to signal all WRs.

MLX5DV_QP_CREATE_PACKET_BASED_CREDIT_MODE: Set QP to work in end-to-end packet-based credit, instead of the default message-based credits (IB spec. section 9.7.7.2).

It is the applications responsibility to make sure that the peer QP is configured with same mode.

MLX5DV_QP_CREATE_SIG_PIPELINING: If the flag is set, the QP is moved to SQD state upon encountering a signature error, and IBV_EVENT_SQ_DRAINED is generated to inform about the new state. The signature pipelining feature is a performance optimization, which reduces latency for read operations in the storage protocols. The feature is optional. Creating the QP fails if the kernel or device does not support the feature. In this case, an application should fallback to backward compatibility mode and handle read operations without the pipelining. See details about the signature pipelining in mlx5dv_qp_cancel_posted_send_wrs(3).

DC init attributes.

dc_init_attr

struct mlx5dv_dci_streams {
    uint8_t log_num_concurent;
    uint8_t log_num_errored;
};
struct mlx5dv_dc_init_attr {
    enum mlx5dv_dc_type dc_type;
    union {
        uint64_t dct_access_key;
        struct mlx5dv_dci_streams dci_streams;
    };
};
MLX5DV_DCTYPE_DCT QP type: Target DC. MLX5DV_DCTYPE_DCI QP type: Initiator DC.
used to create a DCT QP.
dci_streams used to define DCI QP with multiple concurrent streams. Valid when comp_mask includes MLX5DV_QP_INIT_ATTR_MASK_DCI_STREAMS.

log_num_concurent Defines the number of parallel different streams that could be handled by HW. All work request of a specific stream_id are handled in order.

log_num_errored Defines the number of dci error stream channels before moving DCI to an error state.

A bitwise OR of the various values described below.

MLX5DV_QP_EX_WITH_MR_INTERLEAVED: Enables the mlx5dv_wr_mr_interleaved() work requset on this QP.

MLX5DV_QP_EX_WITH_MR_LIST: Enables the mlx5dv_wr_mr_list() work requset on this QP.

MLX5DV_QP_EX_WITH_MKEY_CONFIGURE: Enables the mlx5dv_wr_mkey_configure() work request and the related setters on this QP.

NOTES

mlx5dv_qp_ex_from_ibv_qp_ex() is used to get struct mlx5dv_qp_ex for accessing the send ops interfaces when IBV_QP_INIT_ATTR_SEND_OPS_FLAGS is used.

The MLX5DV_QP_CREATE_DISABLE_SCATTER_TO_CQE flag should be set in cases that IOVA doesn't match the process' VA and the message payload size is small enough to trigger the scatter to CQE feature.

When device memory is used IBV_SEND_INLINE and scatter to CQE should not be used, as the memcpy is not possible.

RETURN VALUE

mlx5dv_create_qp() returns a pointer to the created QP, on error NULL will be returned and errno will be set.

SEE ALSO

ibv_query_device_ex(3), ibv_create_qp_ex(3),

AUTHOR

Yonatan Cohen <yonatanc@mellanox.com>

2018-9-1 mlx5