doc: fix numbers power of 2 in LPM6 guide

[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 4f997d4..171e009 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
 =============


@@ -53,7 +26,7 @@ vhost library should be able to:
 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)``
 


@@ -78,45 +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_USER_DEQUEUE_ZERO_COPY``
+  - ``RTE_VHOST_USER_IOMMU_SUPPORT``

 
 

-    Dequeue zero copy will be enabled when this flag is set. It is disabled by
+    IOMMU support will be enabled when this flag is set. It is disabled by

     default.
 
     default.
 

-    There are some truths (including limitations) you might want to know while
-    setting this flag:
+    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.

 
 

-    * zero copy is not good for small packets (typically for packet size below
-      512).
+  - ``RTE_VHOST_USER_POSTCOPY_SUPPORT``

 
 

-    * zero copy is really good for VM2VM case. For iperf between two VMs, the
-      boost could be above 70% (when TSO is enableld).
+    Postcopy live-migration support will be enabled when this flag is set.
+    It is disabled by default.

 
 

-    * for VM2NIC case, the ``nb_tx_desc`` has to be small enough: <= 64 if virtio
-      indirect feature is not enabled and <= 128 if it is enabled.
+    Enabling this flag should only be done when the calling application does
+    not pre-fault the guest shared memory, otherwise migration would fail.

 
 

-      The is because when dequeue zero copy is enabled, guest Tx used vring will
-      be updated only when corresponding mbuf is freed. Thus, the nb_tx_desc
-      has to be small enough so that the PMD driver will run out of available
-      Tx descriptors and free mbufs timely. Otherwise, guest Tx vring would be
-      starved.
+  - ``RTE_VHOST_USER_LINEARBUF_SUPPORT``

 
 

-    * Guest memory should be backended with huge pages to achieve better
-      performance. Using 1G page size is the best.
+    Enabling this flag forces vhost dequeue function to only provide linear
+    pktmbuf (no multi-segmented pktmbuf).

 
 

-      When dequeue zero copy is enabled, the guest phys address and host phys
-      address mapping has to be established. Using non-huge pages means far
-      more page segments. To make it simple, DPDK vhost does a linear search
-      of those segments, thus the fewer the segments, the quicker we will get
-      the mapping. NOTE: we may speed it by using tree searching in future.
+    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.

 
 

-* ``rte_vhost_driver_session_start()``
+    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.

 
 

-  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.
+    It is disabled by default.

 
 

-* ``rte_vhost_driver_callback_register(virtio_net_device_ops)``
+  - ``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``
+
+    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.
+
+    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


@@ -124,19 +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.


@@ -145,12 +193,115 @@ 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).
+
+* ``rte_vhost_crypto_set_zero_copy(vid, option)``
+
+  Enable or disable zero copy feature of the vhost crypto backend.
+
+* ``rte_vhost_async_channel_register(vid, queue_id, config, ops)``
+
+  Register an async copy device channel for a vhost queue after vring
+  is enabled. Following device ``config`` must be specified together
+  with the registration:
+
+  * ``features``
+
+    This field is used to specify async copy device features.
+
+    ``RTE_VHOST_ASYNC_INORDER`` represents the async copy device can
+    guarantee the order of copy completion is the same as the order
+    of copy submission.
+
+    Currently, only ``RTE_VHOST_ASYNC_INORDER`` capable device is
+    supported by vhost.
+
+  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_register_thread_unsafe(vid, queue_id, config, ops)``
+
+  Register an async copy device channel for a vhost queue without
+  performing any locking.
+
+  This function is only safe to call in vhost callback functions
+  (i.e., struct vhost_device_ops).
+
+* ``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_async_channel_unregister_thread_unsafe(vid, queue_id)``
+
+  Unregister the async copy device channel for a vhost queue without
+  performing any locking.
+
+  This function is only safe to call in vhost callback functions
+  (i.e., struct vhost_device_ops).
+
+* ``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``.
+
+* ``rte_vhost_async_get_inflight(vid, queue_id)``
+
+  This function returns the amount of in-flight packets for the vhost
+  queue using async acceleration.
+
+* ``rte_vhost_clear_queue_thread_unsafe(vid, queue_id, **pkts, count)``
+
+  Clear inflight packets which are submitted to DMA engine in vhost async data
+  path. Completed packets are returned to applications through ``pkts``.

 
 Vhost-user Implementations
 --------------------------
 
 Vhost-user Implementations
 --------------------------


@@ -206,8 +357,88 @@ the vhost device from the data plane.
 
 When the socket connection is closed, vhost will destroy the device.
 
 
 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.