docs/system: Add vhost-user-input documentation
This adds basic documentation for vhost-user-input.
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Message-Id: <20231120043721.50555-3-leo.yan@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240104210945.1223134-10-alex.bennee@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index aff5342..66c9e81 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2289,6 +2289,7 @@
virtio-input
M: Gerd Hoffmann <kraxel@redhat.com>
S: Odd Fixes
+F: docs/system/devices/vhost-user-input.rst
F: hw/input/vhost-user-input.c
F: hw/input/virtio-input*.c
F: include/hw/virtio/virtio-input.h
diff --git a/docs/system/device-emulation.rst b/docs/system/device-emulation.rst
index d1f3277..f197774 100644
--- a/docs/system/device-emulation.rst
+++ b/docs/system/device-emulation.rst
@@ -94,6 +94,7 @@
devices/virtio-gpu.rst
devices/virtio-pmem.rst
devices/virtio-snd.rst
+ devices/vhost-user-input.rst
devices/vhost-user-rng.rst
devices/canokey.rst
devices/usb-u2f.rst
diff --git a/docs/system/devices/vhost-user-input.rst b/docs/system/devices/vhost-user-input.rst
new file mode 100644
index 0000000..118eb78
--- /dev/null
+++ b/docs/system/devices/vhost-user-input.rst
@@ -0,0 +1,45 @@
+.. _vhost_user_input:
+
+QEMU vhost-user-input - Input emulation
+=======================================
+
+This document describes the setup and usage of the Virtio input device.
+The Virtio input device is a paravirtualized device for input events.
+
+Description
+-----------
+
+The vhost-user-input device implementation was designed to work with a daemon
+polling on input devices and passes input events to the guest.
+
+QEMU provides a backend implementation in contrib/vhost-user-input.
+
+Linux kernel support
+--------------------
+
+Virtio input requires a guest Linux kernel built with the
+``CONFIG_VIRTIO_INPUT`` option.
+
+Examples
+--------
+
+The backend daemon should be started first:
+
+::
+
+ host# vhost-user-input --socket-path=input.sock \
+ --evdev-path=/dev/input/event17
+
+The QEMU invocation needs to create a chardev socket to communicate with the
+backend daemon and access the VirtIO queues with the guest over the
+:ref:`shared memory <shared_memory_object>`.
+
+::
+
+ host# qemu-system \
+ -chardev socket,path=/tmp/input.sock,id=mouse0 \
+ -device vhost-user-input-pci,chardev=mouse0 \
+ -m 4096 \
+ -object memory-backend-file,id=mem,size=4G,mem-path=/dev/shm,share=on \
+ -numa node,memdev=mem \
+ ...
diff --git a/docs/system/devices/vhost-user.rst b/docs/system/devices/vhost-user.rst
index c6afc48..9b2da10 100644
--- a/docs/system/devices/vhost-user.rst
+++ b/docs/system/devices/vhost-user.rst
@@ -42,7 +42,7 @@
- See https://github.com/rust-vmm/vhost-device
* - vhost-user-input
- Generic input driver
- - See contrib/vhost-user-input
+ - :ref:`vhost_user_input`
* - vhost-user-rng
- Entropy driver
- :ref:`vhost_user_rng`
@@ -91,6 +91,8 @@
that can be built when enabled by the project although any daemon that
meets the specification for a given device can be used.
+.. _shared_memory_object:
+
Shared memory object
====================
