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Add some basic documentation on vfio-user usage. Signed-off-by: John Levon <john.levon@nutanix.com> Reviewed-by: Cédric Le Goater <clg@redhat.com> Link: https://lore.kernel.org/qemu-devel/20250625193012.2316242-19-john.levon@nutanix.com Signed-off-by: Cédric Le Goater <clg@redhat.com>
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1,008 B
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26 lines
1,008 B
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.. SPDX-License-Identifier: GPL-2.0-or-later
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=========
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vfio-user
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=========
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QEMU includes a ``vfio-user`` client. The ``vfio-user`` specification allows for
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implementing (PCI) devices in userspace outside of QEMU; it is similar to
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``vhost-user`` in this respect (see :doc:`vhost-user`), but can emulate arbitrary
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PCI devices, not just ``virtio``. Whereas ``vfio`` is handled by the host
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kernel, ``vfio-user``, while similar in implementation, is handled entirely in
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userspace.
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For example, SPDK includes a virtual PCI NVMe controller implementation; by
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setting up a ``vfio-user`` UNIX socket between QEMU and SPDK, a VM can send NVMe
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I/O to the SPDK process.
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Presuming a suitable ``vfio-user`` server has opened a socket at
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``/tmp/vfio-user.sock``, a device can be configured with for example:
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.. code-block:: console
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-device '{"driver": "vfio-user-pci","socket": {"path": "/tmp/vfio-user.sock", "type": "unix"}}'
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See `libvfio-user <https://github.com/nutanix/libvfio-user/>`_ for further
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information.
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