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c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1750924009; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=IErTZzC51n5Uhzt0ReIfXt+k26ISLRH++xMSba06ZjI=; b=iSbvGkXj+booGIY2gImmmDjaA5EhQL0ytOVFKYmlju+kCAoQDvrrSbCh76dpDKWygdJgMm vtSpweCdcmmlmuvRiFFVFjhW6Myv8flTgmpfFwXmIXtbMYN+veqAd6X9PYgqFUX6mD2krn cmVh7W8PJEZCgHtwyGh92FEO8Hs0SJU= X-MC-Unique: 2-fBjaM1PUevB3jQYYgVRA-1 X-Mimecast-MFC-AGG-ID: 2-fBjaM1PUevB3jQYYgVRA_1750924004 From: =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= To: qemu-devel@nongnu.org Cc: Alex Williamson , John Levon , =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= Subject: [PULL 24/25] docs: add vfio-user documentation Date: Thu, 26 Jun 2025 09:45:28 +0200 Message-ID: <20250626074529.1384114-25-clg@redhat.com> In-Reply-To: <20250626074529.1384114-1-clg@redhat.com> References: <20250626074529.1384114-1-clg@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=clg@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1750924220196116600 From: John Levon Add some basic documentation on vfio-user usage. Signed-off-by: John Levon Reviewed-by: C=C3=A9dric Le Goater Link: https://lore.kernel.org/qemu-devel/20250625193012.2316242-19-john.lev= on@nutanix.com Signed-off-by: C=C3=A9dric Le Goater --- docs/system/device-emulation.rst | 1 + docs/system/devices/vfio-user.rst | 26 ++++++++++++++++++++++++++ 2 files changed, 27 insertions(+) create mode 100644 docs/system/devices/vfio-user.rst diff --git a/docs/system/device-emulation.rst b/docs/system/device-emulatio= n.rst index a1b0d7997e04f781484a0d48085858f39ee17e35..911381643f1c617dca1021962bc= 4446dbec73ec1 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-u= ser.rst new file mode 100644 index 0000000000000000000000000000000000000000..b6dcaa5615e5354e80e63925f0a= 37537ca9e9371 --- /dev/null +++ b/docs/system/devices/vfio-user.rst @@ -0,0 +1,26 @@ +.. SPDX-License-Identifier: GPL-2.0-or-later + +=3D=3D=3D=3D=3D=3D=3D=3D=3D +vfio-user +=3D=3D=3D=3D=3D=3D=3D=3D=3D + +QEMU includes a ``vfio-user`` client. The ``vfio-user`` specification allo= ws 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 ar= bitrary +PCI devices, not just ``virtio``. Whereas ``vfio`` is handled by the host +kernel, ``vfio-user``, while similar in implementation, is handled entirel= y 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 sen= d 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.soc= k", "type": "unix"}}' + +See `libvfio-user `_ for further +information. --=20 2.49.0