net/cnxk: support flow RSS

[dpdk.git] / doc / guides / prog_guide / vhost_lib.rst

diff --git a/doc/guides/prog_guide/vhost_lib.rst b/doc/guides/prog_guide/vhost_lib.rst
index 6b0c6b2..d18fb98 100644 (file)
--- a/doc/guides/prog_guide/vhost_lib.rst
+++ b/doc/guides/prog_guide/vhost_lib.rst
@@ -1,32 +1,5 @@
-..  BSD LICENSE
-    Copyright(c) 2010-2016 Intel Corporation. All rights reserved.
-    All rights reserved.
-
-    Redistribution and use in source and binary forms, with or without
-    modification, are permitted provided that the following conditions
-    are met:
-
-    * Redistributions of source code must retain the above copyright
-    notice, this list of conditions and the following disclaimer.
-    * Redistributions in binary form must reproduce the above copyright
-    notice, this list of conditions and the following disclaimer in
-    the documentation and/or other materials provided with the
-    distribution.
-    * Neither the name of Intel Corporation nor the names of its
-    contributors may be used to endorse or promote products derived
-    from this software without specific prior written permission.
-
-    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-    A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-    OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-    SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-    LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-    DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-    OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+..  SPDX-License-Identifier: BSD-3-Clause
+    Copyright(c) 2010-2016 Intel Corporation.

 
 Vhost Library
 =============
 
 Vhost Library
 =============


@@ -46,40 +19,21 @@ vhost library should be able to:
 * Know all the necessary information about the vring:
 
   Information such as where the available ring is stored. Vhost defines some
 * Know all the necessary information about the vring:
 
   Information such as where the available ring is stored. Vhost defines some

-  messages to tell the backend all the information it needs to know how to
-  manipulate the vring.
-
-Currently, there are two ways to pass these messages and as a result there are
-two Vhost implementations in DPDK: *vhost-cuse* (where the character devices
-are in user space) and *vhost-user*.
-
-Vhost-cuse creates a user space character device and hook to a function ioctl,
-so that all ioctl commands that are sent from the frontend (QEMU) will be
-captured and handled.
-
-Vhost-user creates a Unix domain socket file through which messages are
-passed.
-
-.. Note::
-
-   Since DPDK v2.2, the majority of the development effort has gone into
-   enhancing vhost-user, such as multiple queue, live migration, and
-   reconnect. Thus, it is strongly advised to use vhost-user instead of
-   vhost-cuse.
+  messages (passed through a Unix domain socket file) to tell the backend all
+  the information it needs to know how to manipulate the vring.

 
 
 Vhost API Overview
 ------------------
 
 
 
 Vhost API Overview
 ------------------
 

-The following is an overview of the Vhost API functions:
+The following is an overview of some key Vhost API functions:

 
 * ``rte_vhost_driver_register(path, flags)``
 
 
 * ``rte_vhost_driver_register(path, flags)``
 

-  This function registers a vhost driver into the system. For vhost-cuse, a
-  ``/dev/path`` character device file will be created. For vhost-user server
-  mode, a Unix domain socket file ``path`` will be created.
+  This function registers a vhost driver into the system. ``path`` specifies
+  the Unix domain socket file path.

 
 

-  Currently two flags are supported (these are valid for vhost-user only):
+  Currently supported flags are:

 
   - ``RTE_VHOST_USER_CLIENT``
 
 
   - ``RTE_VHOST_USER_CLIENT``
 


@@ -97,13 +51,92 @@ The following is an overview of the Vhost API functions:
     This reconnect option is enabled by default. However, it can be turned off
     by setting this flag.
 
     This reconnect option is enabled by default. However, it can be turned off
     by setting this flag.
 

-* ``rte_vhost_driver_session_start()``
+  - ``RTE_VHOST_USER_IOMMU_SUPPORT``
+
+    IOMMU support will be enabled when this flag is set. It is disabled by
+    default.
+
+    Enabling this flag makes possible to use guest vIOMMU to protect vhost
+    from accessing memory the virtio device isn't allowed to, when the feature
+    is negotiated and an IOMMU device is declared.
+
+  - ``RTE_VHOST_USER_POSTCOPY_SUPPORT``
+
+    Postcopy live-migration support will be enabled when this flag is set.
+    It is disabled by default.
+
+    Enabling this flag should only be done when the calling application does
+    not pre-fault the guest shared memory, otherwise migration would fail.
+
+  - ``RTE_VHOST_USER_LINEARBUF_SUPPORT``
+
+    Enabling this flag forces vhost dequeue function to only provide linear
+    pktmbuf (no multi-segmented pktmbuf).
+
+    The vhost library by default provides a single pktmbuf for given a
+    packet, but if for some reason the data doesn't fit into a single
+    pktmbuf (e.g., TSO is enabled), the library will allocate additional
+    pktmbufs from the same mempool and chain them together to create a
+    multi-segmented pktmbuf.
+
+    However, the vhost application needs to support multi-segmented format.
+    If the vhost application does not support that format and requires large
+    buffers to be dequeue, this flag should be enabled to force only linear
+    buffers (see RTE_VHOST_USER_EXTBUF_SUPPORT) or drop the packet.
+
+    It is disabled by default.
+
+  - ``RTE_VHOST_USER_EXTBUF_SUPPORT``
+
+    Enabling this flag allows vhost dequeue function to allocate and attach
+    an external buffer to a pktmbuf if the pkmbuf doesn't provide enough
+    space to store all data.
+
+    This is useful when the vhost application wants to support large packets
+    but doesn't want to increase the default mempool object size nor to
+    support multi-segmented mbufs (non-linear). In this case, a fresh buffer
+    is allocated using rte_malloc() which gets attached to a pktmbuf using
+    rte_pktmbuf_attach_extbuf().
+
+    See RTE_VHOST_USER_LINEARBUF_SUPPORT as well to disable multi-segmented
+    mbufs for application that doesn't support chained mbufs.
+
+    It is disabled by default.
+
+  - ``RTE_VHOST_USER_ASYNC_COPY``
+
+    Asynchronous data path will be enabled when this flag is set. Async data
+    path allows applications to register async copy devices (typically
+    hardware DMA channels) to the vhost queues. Vhost leverages the copy
+    device registered to free CPU from memory copy operations. A set of
+    async data path APIs are defined for DPDK applications to make use of
+    the async capability. Only packets enqueued/dequeued by async APIs are
+    processed through the async data path.
+
+    Currently this feature is only implemented on split ring enqueue data
+    path.
+
+    It is disabled by default.
+
+  - ``RTE_VHOST_USER_NET_COMPLIANT_OL_FLAGS``

 
 

-  This function starts the vhost session loop to handle vhost messages. It
-  starts an infinite loop, therefore it should be called in a dedicated
-  thread.
+    Since v16.04, the vhost library forwards checksum and gso requests for
+    packets received from a virtio driver by filling Tx offload metadata in
+    the mbuf. This behavior is inconsistent with other drivers but it is left
+    untouched for existing applications that might rely on it.

 
 

-* ``rte_vhost_driver_callback_register(virtio_net_device_ops)``
+    This flag disables the legacy behavior and instead ask vhost to simply
+    populate Rx offload metadata in the mbuf.
+
+    It is disabled by default.
+
+* ``rte_vhost_driver_set_features(path, features)``
+
+  This function sets the feature bits the vhost-user driver supports. The
+  vhost-user driver could be vhost-user net, yet it could be something else,
+  say, vhost-user SCSI.
+
+* ``rte_vhost_driver_callback_register(path, vhost_device_ops)``

 
   This function registers a set of callbacks, to let DPDK applications take
   the appropriate action when some events happen. The following events are
 
   This function registers a set of callbacks, to let DPDK applications take
   the appropriate action when some events happen. The following events are


@@ -111,19 +144,47 @@ The following is an overview of the Vhost API functions:
 
   * ``new_device(int vid)``
 
 
   * ``new_device(int vid)``
 

-    This callback is invoked when a virtio net device becomes ready. ``vid``
-    is the virtio net device ID.
+    This callback is invoked when a virtio device becomes ready. ``vid``
+    is the vhost device ID.

 
   * ``destroy_device(int vid)``
 
 
   * ``destroy_device(int vid)``
 

-    This callback is invoked when a virtio net device shuts down (or when the
-    vhost connection is broken).
+    This callback is invoked when a virtio device is paused or shut down.

 
   * ``vring_state_changed(int vid, uint16_t queue_id, int enable)``
 
     This callback is invoked when a specific queue's state is changed, for
     example to enabled or disabled.
 
 
   * ``vring_state_changed(int vid, uint16_t queue_id, int enable)``
 
     This callback is invoked when a specific queue's state is changed, for
     example to enabled or disabled.
 

+  * ``features_changed(int vid, uint64_t features)``
+
+    This callback is invoked when the features is changed. For example,
+    ``VHOST_F_LOG_ALL`` will be set/cleared at the start/end of live
+    migration, respectively.
+
+  * ``new_connection(int vid)``
+
+    This callback is invoked on new vhost-user socket connection. If DPDK
+    acts as the server the device should not be deleted before
+    ``destroy_connection`` callback is received.
+
+  * ``destroy_connection(int vid)``
+
+    This callback is invoked when vhost-user socket connection is closed.
+    It indicates that device with id ``vid`` is no longer in use and can be
+    safely deleted.
+
+* ``rte_vhost_driver_disable/enable_features(path, features))``
+
+  This function disables/enables some features. For example, it can be used to
+  disable mergeable buffers and TSO features, which both are enabled by
+  default.
+
+* ``rte_vhost_driver_start(path)``
+
+  This function triggers the vhost-user negotiation. It should be invoked at
+  the end of initializing a vhost-user driver.
+

 * ``rte_vhost_enqueue_burst(vid, queue_id, pkts, count)``
 
   Transmits (enqueues) ``count`` packets from host to guest.
 * ``rte_vhost_enqueue_burst(vid, queue_id, pkts, count)``
 
   Transmits (enqueues) ``count`` packets from host to guest.


@@ -132,42 +193,96 @@ The following is an overview of the Vhost API functions:
 
   Receives (dequeues) ``count`` packets from guest, and stored them at ``pkts``.
 
 
   Receives (dequeues) ``count`` packets from guest, and stored them at ``pkts``.
 

-* ``rte_vhost_feature_disable/rte_vhost_feature_enable(feature_mask)``
+* ``rte_vhost_crypto_create(vid, cryptodev_id, sess_mempool, socket_id)``

 
 

-  This function disables/enables some features. For example, it can be used to
-  disable mergeable buffers and TSO features, which both are enabled by
-  default.
+  As an extension of new_device(), this function adds virtio-crypto workload
+  acceleration capability to the device. All crypto workload is processed by
+  DPDK cryptodev with the device ID of ``cryptodev_id``.
+
+* ``rte_vhost_crypto_free(vid)``
+
+  Frees the memory and vhost-user message handlers created in
+  rte_vhost_crypto_create().
+
+* ``rte_vhost_crypto_fetch_requests(vid, queue_id, ops, nb_ops)``
+
+  Receives (dequeues) ``nb_ops`` virtio-crypto requests from guest, parses
+  them to DPDK Crypto Operations, and fills the ``ops`` with parsing results.
+
+* ``rte_vhost_crypto_finalize_requests(queue_id, ops, nb_ops)``

 
 

+  After the ``ops`` are dequeued from Cryptodev, finalizes the jobs and
+  notifies the guest(s).

 
 

-Vhost Implementations
----------------------
+* ``rte_vhost_crypto_set_zero_copy(vid, option)``

 
 

-Vhost-cuse implementation
-~~~~~~~~~~~~~~~~~~~~~~~~~
+  Enable or disable zero copy feature of the vhost crypto backend.

 
 

-When vSwitch registers the vhost driver, it will register a cuse device driver
-into the system and creates a character device file. This cuse driver will
-receive vhost open/release/IOCTL messages from the QEMU simulator.
+* ``rte_vhost_async_channel_register(vid, queue_id, features, ops)``

 
 

-When the open call is received, the vhost driver will create a vhost device
-for the virtio device in the guest.
+  Register a vhost queue with async copy device channel after vring
+  is enabled. Following device ``features`` must be specified together
+  with the registration:

 
 

-When the ``VHOST_SET_MEM_TABLE`` ioctl is received, vhost searches the memory
-region to find the starting user space virtual address that maps the memory of
-the guest virtual machine. Through this virtual address and the QEMU pid,
-vhost can find the file QEMU uses to map the guest memory. Vhost maps this
-file into its address space, in this way vhost can fully access the guest
-physical memory, which means vhost could access the shared virtio ring and the
-guest physical address specified in the entry of the ring.
+  * ``async_inorder``

 
 

-The guest virtual machine tells the vhost whether the virtio device is ready
-for processing or is de-activated through the ``VHOST_NET_SET_BACKEND``
-message. The registered callback from vSwitch will be called.
+    Async copy device can guarantee the ordering of copy completion
+    sequence. Copies are completed in the same order with that at
+    the submission time.

 
 

-When the release call is made, vhost will destroy the device.
+    Currently, only ``async_inorder`` capable device is supported by vhost.

 
 

-Vhost-user implementation
-~~~~~~~~~~~~~~~~~~~~~~~~~
+  * ``async_threshold``
+
+    The copy length (in bytes) below which CPU copy will be used even if
+    applications call async vhost APIs to enqueue/dequeue data.
+
+    Typical value is 512~1024 depending on the async device capability.
+
+  Applications must provide following ``ops`` callbacks for vhost lib to
+  work with the async copy devices:
+
+  * ``transfer_data(vid, queue_id, descs, opaque_data, count)``
+
+    vhost invokes this function to submit copy data to the async devices.
+    For non-async_inorder capable devices, ``opaque_data`` could be used
+    for identifying the completed packets.
+
+  * ``check_completed_copies(vid, queue_id, opaque_data, max_packets)``
+
+    vhost invokes this function to get the copy data completed by async
+    devices.
+
+* ``rte_vhost_async_channel_unregister(vid, queue_id)``
+
+  Unregister the async copy device channel from a vhost queue.
+  Unregistration will fail, if the vhost queue has in-flight
+  packets that are not completed.
+
+  Unregister async copy devices in vring_state_changed() may
+  fail, as this API tries to acquire the spinlock of vhost
+  queue. The recommended way is to unregister async copy
+  devices for all vhost queues in destroy_device(), when a
+  virtio device is paused or shut down.
+
+* ``rte_vhost_submit_enqueue_burst(vid, queue_id, pkts, count, comp_pkts, comp_count)``
+
+  Submit an enqueue request to transmit ``count`` packets from host to guest
+  by async data path. Successfully enqueued packets can be transfer completed
+  or being occupied by DMA engines; transfer completed packets are returned in
+  ``comp_pkts``, but others are not guaranteed to finish, when this API
+  call returns.
+
+  Applications must not free the packets submitted for enqueue until the
+  packets are completed.
+
+* ``rte_vhost_poll_enqueue_completed(vid, queue_id, pkts, count)``
+
+  Poll enqueue completion status from async data path. Completed packets
+  are returned to applications through ``pkts``.
+
+Vhost-user Implementations
+--------------------------

 
 Vhost-user uses Unix domain sockets for passing messages. This means the DPDK
 vhost-user implementation has two options:
 
 Vhost-user uses Unix domain sockets for passing messages. This means the DPDK
 vhost-user implementation has two options:


@@ -214,16 +329,94 @@ For ``VHOST_SET_MEM_TABLE`` message, QEMU will send information for each
 memory region and its file descriptor in the ancillary data of the message.
 The file descriptor is used to map that region.
 
 memory region and its file descriptor in the ancillary data of the message.
 The file descriptor is used to map that region.
 

-There is no ``VHOST_NET_SET_BACKEND`` message as in vhost-cuse to signal
-whether the virtio device is ready or stopped. Instead,

 ``VHOST_SET_VRING_KICK`` is used as the signal to put the vhost device into
 the data plane, and ``VHOST_GET_VRING_BASE`` is used as the signal to remove
 the vhost device from the data plane.
 
 When the socket connection is closed, vhost will destroy the device.
 
 ``VHOST_SET_VRING_KICK`` is used as the signal to put the vhost device into
 the data plane, and ``VHOST_GET_VRING_BASE`` is used as the signal to remove
 the vhost device from the data plane.
 
 When the socket connection is closed, vhost will destroy the device.
 

+Guest memory requirement
+------------------------
+
+* Memory pre-allocation
+
+  For non-async data path, guest memory pre-allocation is not a
+  must. This can help save of memory. If users really want the guest memory
+  to be pre-allocated (e.g., for performance reason), we can add option
+  ``-mem-prealloc`` when starting QEMU. Or, we can lock all memory at vhost
+  side which will force memory to be allocated when mmap at vhost side;
+  option --mlockall in ovs-dpdk is an example in hand.
+
+  For async data path, we force the VM memory to be pre-allocated at vhost
+  lib when mapping the guest memory; and also we need to lock the memory to
+  prevent pages being swapped out to disk.
+
+* Memory sharing
+
+  Make sure ``share=on`` QEMU option is given. vhost-user will not work with
+  a QEMU version without shared memory mapping.
+

 Vhost supported vSwitch reference
 ---------------------------------
 
 For more vhost details and how to support vhost in vSwitch, please refer to
 the vhost example in the DPDK Sample Applications Guide.
 Vhost supported vSwitch reference
 ---------------------------------
 
 For more vhost details and how to support vhost in vSwitch, please refer to
 the vhost example in the DPDK Sample Applications Guide.

+
+Vhost data path acceleration (vDPA)
+-----------------------------------
+
+vDPA supports selective datapath in vhost-user lib by enabling virtio ring
+compatible devices to serve virtio driver directly for datapath acceleration.
+
+``rte_vhost_driver_attach_vdpa_device`` is used to configure the vhost device
+with accelerated backend.
+
+Also vhost device capabilities are made configurable to adopt various devices.
+Such capabilities include supported features, protocol features, queue number.
+
+Finally, a set of device ops is defined for device specific operations:
+
+* ``get_queue_num``
+
+  Called to get supported queue number of the device.
+
+* ``get_features``
+
+  Called to get supported features of the device.
+
+* ``get_protocol_features``
+
+  Called to get supported protocol features of the device.
+
+* ``dev_conf``
+
+  Called to configure the actual device when the virtio device becomes ready.
+
+* ``dev_close``
+
+  Called to close the actual device when the virtio device is stopped.
+
+* ``set_vring_state``
+
+  Called to change the state of the vring in the actual device when vring state
+  changes.
+
+* ``set_features``
+
+  Called to set the negotiated features to device.
+
+* ``migration_done``
+
+  Called to allow the device to response to RARP sending.
+
+* ``get_vfio_group_fd``
+
+   Called to get the VFIO group fd of the device.
+
+* ``get_vfio_device_fd``
+
+  Called to get the VFIO device fd of the device.
+
+* ``get_notify_area``
+
+  Called to get the notify area info of the queue.