2be90f7915
Fixes: 56252de779 ("net/vdev_netvsc: add automatic probing")
Cc: stable@dpdk.org
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
105 lines
3.5 KiB
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105 lines
3.5 KiB
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.. SPDX-License-Identifier: BSD-3-Clause
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Copyright 2017 6WIND S.A.
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Copyright 2017 Mellanox Technologies, Ltd
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VDEV_NETVSC driver
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==================
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The VDEV_NETVSC driver (librte_pmd_vdev_netvsc) provides support for NetVSC
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interfaces and associated SR-IOV virtual function (VF) devices found in
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Linux virtual machines running on Microsoft Hyper-V_ (including Azure)
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platforms.
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.. _Hyper-V: https://docs.microsoft.com/en-us/windows-hardware/drivers/network/overview-of-hyper-v
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Implementation details
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----------------------
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Each instance of this driver effectively needs to drive two devices: the
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NetVSC interface proper and its SR-IOV VF (referred to as "physical" from
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this point on) counterpart sharing the same MAC address.
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Physical devices are part of the host system and cannot be maintained during
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VM migration. From a VM standpoint they appear as hot-plug devices that come
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and go without prior notice.
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When the physical device is present, egress and most of the ingress traffic
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flows through it; only multicasts and other hypervisor control still flow
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through NetVSC. Otherwise, NetVSC acts as a fallback for all traffic.
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To avoid unnecessary code duplication and ensure maximum performance,
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handling of physical devices is left to their original PMDs; this virtual
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device driver (also known as *vdev*) manages other PMDs as summarized by the
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following block diagram::
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.------------------.
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| DPDK application |
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`--------+---------'
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.------+------.
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| DPDK ethdev |
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`------+------' Control
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| |
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.------------+------------. v .--------------------.
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| failsafe PMD +---------+ vdev_netvsc driver |
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`--+-------------------+--' `--------------------'
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| |
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| .........|.........
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| : | :
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.----+----. : .----+----. :
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| tap PMD | : | any PMD | :
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`----+----' : `----+----' : <-- Hot-pluggable
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| : | :
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.------+-------. : .-----+-----. :
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| NetVSC-based | : | SR-IOV VF | :
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| netdevice | : | device | :
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`--------------' : `-----------' :
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:.................:
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This driver implementation may be temporary and should be improved or removed
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either when hot-plug will be fully supported in EAL and bus drivers or when
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a new NetVSC driver will be integrated.
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Build options
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-------------
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- ``CONFIG_RTE_LIBRTE_VDEV_NETVSC_PMD`` (default ``y``)
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Toggle compilation of this driver.
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Run-time parameters
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-------------------
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This driver is invoked automatically in Hyper-V VM systems unless the user
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invoked it by command line using ``--vdev=net_vdev_netvsc`` EAL option.
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The following device parameters are supported:
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- ``iface`` [string]
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Provide a specific NetVSC interface (netdevice) name to attach this driver
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to. Can be provided multiple times for additional instances.
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- ``mac`` [string]
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Same as ``iface`` except a suitable NetVSC interface is located using its
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MAC address.
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- ``force`` [int]
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If nonzero, forces the use of specified interfaces even if not detected as
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NetVSC.
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- ``ignore`` [int]
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If nonzero, ignores the driver running (actually used to disable the
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auto-detection in Hyper-V VM).
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.. note::
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Not specifying either ``iface`` or ``mac`` makes this driver attach itself to
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all unrouted NetVSC interfaces found on the system.
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Specifying the device makes this driver attach itself to the device
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regardless the device routes.
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