99 lines
3.0 KiB
ReStructuredText
99 lines
3.0 KiB
ReStructuredText
.. SPDX-License-Identifier: BSD-3-Clause
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Copyright(c) 2016 IGEL Co., Ltd.
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Poll Mode Driver that wraps vhost library
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=========================================
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This PMD is a thin wrapper of the DPDK vhost library.
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The user can handle virtqueues as one of normal DPDK port.
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Vhost Implementation in DPDK
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----------------------------
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Please refer to Chapter "Vhost Library" of *DPDK Programmer's Guide* to know detail of vhost.
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Features and Limitations of vhost PMD
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-------------------------------------
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Currently, the vhost PMD provides the basic functionality of packet reception, transmission and event handling.
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* It has multiple queues support.
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* It supports ``RTE_ETH_EVENT_INTR_LSC`` and ``RTE_ETH_EVENT_QUEUE_STATE`` events.
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* It supports Port Hotplug functionality.
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* Don't need to stop RX/TX, when the user wants to stop a guest or a virtio-net driver on guest.
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Vhost PMD arguments
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-------------------
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The user can specify below arguments in `--vdev` option.
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#. ``iface``:
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It is used to specify a path to connect to a QEMU virtio-net device.
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#. ``queues``:
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It is used to specify the number of queues virtio-net device has.
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(Default: 1)
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#. ``iommu-support``:
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It is used to enable iommu support in vhost library.
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(Default: 0 (disabled))
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#. ``postcopy-support``:
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It is used to enable postcopy live-migration support in vhost library.
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(Default: 0 (disabled))
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#. ``tso``:
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It is used to enable tso support in vhost library.
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(Default: 0 (disabled))
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Vhost PMD event handling
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------------------------
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This section describes how to handle vhost PMD events.
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The user can register an event callback handler with ``rte_eth_dev_callback_register()``.
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The registered callback handler will be invoked with one of below event types.
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#. ``RTE_ETH_EVENT_INTR_LSC``:
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It means link status of the port was changed.
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#. ``RTE_ETH_EVENT_QUEUE_STATE``:
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It means some of queue statuses were changed. Call ``rte_eth_vhost_get_queue_event()`` in the callback handler.
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Because changing multiple statuses may occur only one event, call the function repeatedly as long as it doesn't return negative value.
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Vhost PMD with testpmd application
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----------------------------------
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This section demonstrates vhost PMD with testpmd DPDK sample application.
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#. Launch the testpmd with vhost PMD:
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.. code-block:: console
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./testpmd -l 0-3 -n 4 --vdev 'net_vhost0,iface=/tmp/sock0,queues=1' -- -i
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Other basic DPDK preparations like hugepage enabling here.
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Please refer to the *DPDK Getting Started Guide* for detailed instructions.
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#. Launch the QEMU:
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.. code-block:: console
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qemu-system-x86_64 <snip>
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-chardev socket,id=chr0,path=/tmp/sock0 \
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-netdev vhost-user,id=net0,chardev=chr0,vhostforce,queues=1 \
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-device virtio-net-pci,netdev=net0
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This command attaches one virtio-net device to QEMU guest.
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After initialization processes between QEMU and DPDK vhost library are done, status of the port will be linked up.
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