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Diffstat (limited to 'docs/system/devices/vfio-user.rst')
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diff --git a/docs/system/devices/vfio-user.rst b/docs/system/devices/vfio-user.rst new file mode 100644 index 0000000..b6dcaa5 --- /dev/null +++ b/docs/system/devices/vfio-user.rst @@ -0,0 +1,26 @@ +.. SPDX-License-Identifier: GPL-2.0-or-later + +========= +vfio-user +========= + +QEMU includes a ``vfio-user`` client. The ``vfio-user`` specification allows for +implementing (PCI) devices in userspace outside of QEMU; it is similar to +``vhost-user`` in this respect (see :doc:`vhost-user`), but can emulate arbitrary +PCI devices, not just ``virtio``. Whereas ``vfio`` is handled by the host +kernel, ``vfio-user``, while similar in implementation, is handled entirely in +userspace. + +For example, SPDK includes a virtual PCI NVMe controller implementation; by +setting up a ``vfio-user`` UNIX socket between QEMU and SPDK, a VM can send NVMe +I/O to the SPDK process. + +Presuming a suitable ``vfio-user`` server has opened a socket at +``/tmp/vfio-user.sock``, a device can be configured with for example: + +.. code-block:: console + +-device '{"driver": "vfio-user-pci","socket": {"path": "/tmp/vfio-user.sock", "type": "unix"}}' + +See `libvfio-user <https://github.com/nutanix/libvfio-user/>`_ for further +information. |