5c060bf178
A new vDPA class was recently introduced. IFC driver implements the vDPA operations, hence it should be moved to the vDPA class. Move it. Signed-off-by: Matan Azrad <matan@mellanox.com> Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
107 lines
3.7 KiB
ReStructuredText
107 lines
3.7 KiB
ReStructuredText
.. SPDX-License-Identifier: BSD-3-Clause
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Copyright(c) 2018 Intel Corporation.
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IFCVF vDPA driver
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=================
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The IFCVF vDPA (vhost data path acceleration) driver provides support for the
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Intel FPGA 100G VF (IFCVF). IFCVF's datapath is virtio ring compatible, it
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works as a HW vhost backend which can send/receive packets to/from virtio
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directly by DMA. Besides, it supports dirty page logging and device state
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report/restore, this driver enables its vDPA functionality.
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Pre-Installation Configuration
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------------------------------
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Config File Options
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~~~~~~~~~~~~~~~~~~~
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The following option can be modified in the ``config`` file.
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- ``CONFIG_RTE_LIBRTE_IFC_PMD`` (default ``y`` for linux)
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Toggle compilation of the ``librte_pmd_ifc`` driver.
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IFCVF vDPA Implementation
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-------------------------
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IFCVF's vendor ID and device ID are same as that of virtio net pci device,
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with its specific subsystem vendor ID and device ID. To let the device be
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probed by IFCVF driver, adding "vdpa=1" parameter helps to specify that this
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device is to be used in vDPA mode, rather than polling mode, virtio pmd will
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skip when it detects this message. If no this parameter specified, device
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will not be used as a vDPA device, and it will be driven by virtio pmd.
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Different VF devices serve different virtio frontends which are in different
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VMs, so each VF needs to have its own DMA address translation service. During
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the driver probe a new container is created for this device, with this
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container vDPA driver can program DMA remapping table with the VM's memory
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region information.
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The device argument "sw-live-migration=1" will configure the driver into SW
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assisted live migration mode. In this mode, the driver will set up a SW relay
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thread when LM happens, this thread will help device to log dirty pages. Thus
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this mode does not require HW to implement a dirty page logging function block,
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but will consume some percentage of CPU resource depending on the network
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throughput. If no this parameter specified, driver will rely on device's logging
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capability.
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Key IFCVF vDPA driver ops
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~~~~~~~~~~~~~~~~~~~~~~~~~
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- ifcvf_dev_config:
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Enable VF data path with virtio information provided by vhost lib, including
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IOMMU programming to enable VF DMA to VM's memory, VFIO interrupt setup to
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route HW interrupt to virtio driver, create notify relay thread to translate
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virtio driver's kick to a MMIO write onto HW, HW queues configuration.
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This function gets called to set up HW data path backend when virtio driver
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in VM gets ready.
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- ifcvf_dev_close:
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Revoke all the setup in ifcvf_dev_config.
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This function gets called when virtio driver stops device in VM.
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To create a vhost port with IFC VF
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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- Create a vhost socket and assign a VF's device ID to this socket via
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vhost API. When QEMU vhost connection gets ready, the assigned VF will
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get configured automatically.
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Features
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--------
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Features of the IFCVF driver are:
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- Compatibility with virtio 0.95 and 1.0.
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- SW assisted vDPA live migration.
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Prerequisites
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-------------
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- Platform with IOMMU feature. IFC VF needs address translation service to
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Rx/Tx directly with virtio driver in VM.
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Limitations
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-----------
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Dependency on vfio-pci
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~~~~~~~~~~~~~~~~~~~~~~
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vDPA driver needs to setup VF MSIX interrupts, each queue's interrupt vector
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is mapped to a callfd associated with a virtio ring. Currently only vfio-pci
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allows multiple interrupts, so the IFCVF driver is dependent on vfio-pci.
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Live Migration with VIRTIO_NET_F_GUEST_ANNOUNCE
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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IFC VF doesn't support RARP packet generation, virtio frontend supporting
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VIRTIO_NET_F_GUEST_ANNOUNCE feature can help to do that.
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