..  SPDX-License-Identifier: BSD-3-Clause
    Copyright 2019 Mellanox Technologies, Ltd

.. include:: <isonum.txt>

NVIDIA MLX5 vDPA Driver
=======================

.. note::

   NVIDIA acquired Mellanox Technologies in 2020.
   The DPDK documentation and code might still include instances
   of or references to Mellanox trademarks (like BlueField and ConnectX)
   that are now NVIDIA trademarks.

The mlx5 vDPA (vhost data path acceleration) driver library
(**librte_vdpa_mlx5**) provides support for **NVIDIA ConnectX-6**,
**NVIDIA ConnectX-6 Dx**, **NVIDIA ConnectX-6 Lx**, **NVIDIA ConnectX7**,
**NVIDIA BlueField** and **NVIDIA BlueField-2** families of
10/25/40/50/100/200 Gb/s adapters as well as their virtual functions (VF) in
SR-IOV context.

.. note::

   This driver is enabled automatically when using "meson" build system which
   will detect dependencies.

See :doc:`../../platform/mlx5` guide for design details,
and which PMDs can be combined with vDPA PMD.

Supported NICs
--------------

* NVIDIA\ |reg| ConnectX\ |reg|-6 200G MCX654106A-HCAT (2x200G)
* NVIDIA\ |reg| ConnectX\ |reg|-6 Dx EN 25G MCX621102AN-ADAT (2x25G)
* NVIDIA\ |reg| ConnectX\ |reg|-6 Dx EN 100G MCX623106AN-CDAT (2x100G)
* NVIDIA\ |reg| ConnectX\ |reg|-6 Dx EN 200G MCX623105AN-VDAT (1x200G)
* NVIDIA\ |reg| ConnectX\ |reg|-6 Lx EN 25G MCX631102AN-ADAT (2x25G)
* NVIDIA\ |reg| ConnectX\ |reg|-7 200G CX713106AE-HEA_QP1_Ax (2x200G)
* NVIDIA\ |reg| BlueField SmartNIC 25G MBF1M332A-ASCAT (2x25G)
* NVIDIA\ |reg| BlueField |reg|-2 SmartNIC MT41686 - MBF2H332A-AEEOT_A1 (2x25G)

Prerequisites
-------------

- NVIDIA MLNX_OFED version: **5.0**
  See :ref:`mlx5 common prerequisites <mlx5_linux_prerequisites>` for more details.

Run-time configuration
~~~~~~~~~~~~~~~~~~~~~~

Driver options
^^^^^^^^^^^^^^

Please refer to :ref:`mlx5 common options <mlx5_common_driver_options>`
for an additional list of options shared with other mlx5 drivers.

- ``event_mode`` parameter [int]

  - 0, Completion queue scheduling will be managed by a timer thread which
    automatically adjusts its delays to the coming traffic rate.

  - 1, Completion queue scheduling will be managed by a timer thread with fixed
    delay time.

  - 2, Completion queue scheduling will be managed by interrupts. Each CQ burst
    arms the CQ in order to get an interrupt event in the next traffic burst.

  - Default mode is 1.

- ``event_us`` parameter [int]

  Per mode micro-seconds parameter - relevant only for event mode 0 and 1:

  - 0, A nonzero value to set timer step in micro-seconds. The timer thread
    dynamic delay change steps according to this value. Default value is 1us.

  - 1, A value to set fixed timer delay in micro-seconds. Default value is 0us.

- ``no_traffic_time`` parameter [int]

  A nonzero value defines the traffic off time, in polling cycle time units,
  that moves the driver to no-traffic mode. In this mode the polling is stopped
  and interrupts are configured to the device in order to notify traffic for the
  driver. Default value is 16.

- ``event_core`` parameter [int]

  The CPU core number of the timer thread, default: EAL main lcore.

.. note::

   This core can be shared among different mlx5 vDPA devices as `event_core`
   but using it also for other tasks may affect the performance and the latency
   of the mlx5 vDPA devices.

- ``max_conf_threads`` parameter [int]

  Allow the driver to use internal threads to obtain fast configuration.
  All the threads will be open on the same core of the event completion queue scheduling thread.

  - 0, default, don't use internal threads for configuration.

  - 1 - 256, number of internal threads in addition to the caller thread (8 is suggested).
    This value, if not 0, should be the same for all the devices;
    the first probing will take it with the ``event_core``
    for all the multi-thread configurations in the driver.

- ``hw_latency_mode`` parameter [int]

  The completion queue moderation mode:

  - 0, HW default.

  - 1, Latency is counted from the first packet completion report.

  - 2, Latency is counted from the last packet completion.

- ``hw_max_latency_us`` parameter [int]

  - 1 - 4095, The maximum time in microseconds that packet completion report
    can be delayed.

  - 0, HW default.

- ``hw_max_pending_comp`` parameter [int]

  - 1 - 65535, The maximum number of pending packets completions in an HW queue.

  - 0, HW default.

- ``queue_size`` parameter [int]

  - 1 - 1024, Virtio queue depth for pre-creating queue resource to speed up
    first time queue creation. Set it together with ``queues`` parameter.

  - 0, default value, no pre-create virtq resource.

- ``queues`` parameter [int]

  - 1 - 128, Maximum number of virtio queue pair (including 1 Rx queue and 1 Tx queue)
    for pre-creating queue resource to speed up first time queue creation.
    Set it together with ``queue_size`` parameter.

  - 0, default value, no pre-create virtq resource.

Error handling
^^^^^^^^^^^^^^

Upon potential hardware errors, mlx5 PMD try to recover, give up if failed 3
times in 3 seconds, virtq will be put in disable state. User should check log
to get error information, or query vdpa statistics counter to know error type
and count report.

Statistics
^^^^^^^^^^

The device statistics counter persists in reconfiguration until the device gets
removed. User can reset counters by calling function rte_vdpa_reset_stats().
