From: John Levon Date: Wed, 25 Jun 2025 19:30:10 +0000 (+0100) Subject: docs: add vfio-user documentation X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=c688cc165b32c924a01a69d90ac9aac6fac8c64c;p=thirdparty%2Fqemu.git docs: add vfio-user documentation Add some basic documentation on vfio-user usage. Signed-off-by: John Levon Reviewed-by: Cédric Le Goater Link: https://lore.kernel.org/qemu-devel/20250625193012.2316242-19-john.levon@nutanix.com Signed-off-by: Cédric Le Goater --- diff --git a/docs/system/device-emulation.rst b/docs/system/device-emulation.rst index a1b0d7997e..911381643f 100644 --- a/docs/system/device-emulation.rst +++ b/docs/system/device-emulation.rst @@ -85,6 +85,7 @@ Emulated Devices devices/can.rst devices/ccid.rst devices/cxl.rst + devices/vfio-user.rst devices/ivshmem.rst devices/ivshmem-flat.rst devices/keyboard.rst diff --git a/docs/system/devices/vfio-user.rst b/docs/system/devices/vfio-user.rst new file mode 100644 index 0000000000..b6dcaa5615 --- /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 `_ for further +information.