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diff --git a/docs/system/sriov.rst b/docs/system/sriov.rst new file mode 100644 index 0000000000..a851a66a4b --- /dev/null +++ b/docs/system/sriov.rst @@ -0,0 +1,36 @@ +.. SPDX-License-Identifier: GPL-2.0-or-later + +Compsable SR-IOV device +======================= + +SR-IOV (Single Root I/O Virtualization) is an optional extended capability of a +PCI Express device. It allows a single physical function (PF) to appear as +multiple virtual functions (VFs) for the main purpose of eliminating software +overhead in I/O from virtual machines. + +There are devices with predefined SR-IOV configurations, but it is also possible +to compose an SR-IOV device yourself. Composing an SR-IOV device is currently +only supported by virtio-net-pci. + +Users can configure an SR-IOV-capable virtio-net device by adding +virtio-net-pci functions to a bus. Below is a command line example: + +.. code-block:: shell + + -netdev user,id=n -netdev user,id=o + -netdev user,id=p -netdev user,id=q + -device pcie-root-port,id=b + -device virtio-net-pci,bus=b,addr=0x0.0x3,netdev=q,sriov-pf=f + -device virtio-net-pci,bus=b,addr=0x0.0x2,netdev=p,sriov-pf=f + -device virtio-net-pci,bus=b,addr=0x0.0x1,netdev=o,sriov-pf=f + -device virtio-net-pci,bus=b,addr=0x0.0x0,netdev=n,id=f + +The VFs specify the paired PF with ``sriov-pf`` property. The PF must be +added after all VFs. It is the user's responsibility to ensure that VFs have +function numbers larger than one of the PF, and that the function numbers +have a consistent stride. + +You may also need to perform additional steps to activate the SR-IOV feature on +your guest. For Linux, refer to [1]_. + +.. [1] https://docs.kernel.org/PCI/pci-iov-howto.html |