1 .. SPDX-License-Identifier: BSD-3-Clause
2 Copyright(c) 2018 Intel Corporation.
7 The IFCVF vDPA (vhost data path acceleration) driver provides support for the
8 Intel FPGA 100G VF (IFCVF). IFCVF's datapath is virtio ring compatible, it
9 works as a HW vhost backend which can send/receive packets to/from virtio
10 directly by DMA. Besides, it supports dirty page logging and device state
11 report/restore, this driver enables its vDPA functionality.
14 Pre-Installation Configuration
15 ------------------------------
20 The following option can be modified in the ``config`` file.
22 - ``CONFIG_RTE_LIBRTE_IFC_PMD`` (default ``y`` for linux)
24 Toggle compilation of the ``librte_pmd_ifc`` driver.
27 IFCVF vDPA Implementation
28 -------------------------
30 IFCVF's vendor ID and device ID are same as that of virtio net pci device,
31 with its specific subsystem vendor ID and device ID. To let the device be
32 probed by IFCVF driver, adding "vdpa=1" parameter helps to specify that this
33 device is to be used in vDPA mode, rather than polling mode, virtio pmd will
34 skip when it detects this message. If no this parameter specified, device
35 will not be used as a vDPA device, and it will be driven by virtio pmd.
37 Different VF devices serve different virtio frontends which are in different
38 VMs, so each VF needs to have its own DMA address translation service. During
39 the driver probe a new container is created for this device, with this
40 container vDPA driver can program DMA remapping table with the VM's memory
43 The device argument "sw-live-migration=1" will configure the driver into SW
44 assisted live migration mode. In this mode, the driver will set up a SW relay
45 thread when LM happens, this thread will help device to log dirty pages. Thus
46 this mode does not require HW to implement a dirty page logging function block,
47 but will consume some percentage of CPU resource depending on the network
48 throughput. If no this parameter specified, driver will rely on device's logging
51 Key IFCVF vDPA driver ops
52 ~~~~~~~~~~~~~~~~~~~~~~~~~
55 Enable VF data path with virtio information provided by vhost lib, including
56 IOMMU programming to enable VF DMA to VM's memory, VFIO interrupt setup to
57 route HW interrupt to virtio driver, create notify relay thread to translate
58 virtio driver's kick to a MMIO write onto HW, HW queues configuration.
60 This function gets called to set up HW data path backend when virtio driver
64 Revoke all the setup in ifcvf_dev_config.
66 This function gets called when virtio driver stops device in VM.
68 To create a vhost port with IFC VF
69 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
71 - Create a vhost socket and assign a VF's device ID to this socket via
72 vhost API. When QEMU vhost connection gets ready, the assigned VF will
73 get configured automatically.
79 Features of the IFCVF driver are:
81 - Compatibility with virtio 0.95 and 1.0.
82 - SW assisted vDPA live migration.
88 - Platform with IOMMU feature. IFC VF needs address translation service to
89 Rx/Tx directly with virtio driver in VM.
95 Dependency on vfio-pci
96 ~~~~~~~~~~~~~~~~~~~~~~
98 vDPA driver needs to setup VF MSIX interrupts, each queue's interrupt vector
99 is mapped to a callfd associated with a virtio ring. Currently only vfio-pci
100 allows multiple interrupts, so the IFCVF driver is dependent on vfio-pci.
102 Live Migration with VIRTIO_NET_F_GUEST_ANNOUNCE
103 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
105 IFC VF doesn't support RARP packet generation, virtio frontend supporting
106 VIRTIO_NET_F_GUEST_ANNOUNCE feature can help to do that.