From 28ed79b98f08b5701dcaab7c6ad1015602b28e02 Mon Sep 17 00:00:00 2001
From: libai <libai12@huawei.com>
Date: Sat, 12 Nov 2022 22:40:13 +0800
Subject: [PATCH] docs: Add generic vhost-vdpa device documentation

Add the description of the generic vhost-vdpa device

Signed-off-by: libai <libai12@huawei.com>
---
 docs/system/device-emulation.rst              |  1 +
 .../devices/vhost-vdpa-generic-device.rst     | 46 +++++++++++++++++++
 2 files changed, 47 insertions(+)
 create mode 100644 docs/system/devices/vhost-vdpa-generic-device.rst

diff --git a/docs/system/device-emulation.rst b/docs/system/device-emulation.rst
index d1f3277cb0..e1b2d18fb1 100644
--- a/docs/system/device-emulation.rst
+++ b/docs/system/device-emulation.rst
@@ -98,3 +98,4 @@ Emulated Devices
    devices/canokey.rst
    devices/usb-u2f.rst
    devices/igb.rst
+   devices/vhost-vdpa-generic-device.rst
diff --git a/docs/system/devices/vhost-vdpa-generic-device.rst b/docs/system/devices/vhost-vdpa-generic-device.rst
new file mode 100644
index 0000000000..25fbcac60e
--- /dev/null
+++ b/docs/system/devices/vhost-vdpa-generic-device.rst
@@ -0,0 +1,46 @@
+
+=========================
+vhost-vDPA generic device
+=========================
+
+This document explains the usage of the vhost-vDPA generic device.
+
+Description
+-----------
+
+vDPA(virtio data path acceleration) device is a device that uses a datapath
+which complies with the virtio specifications with vendor specific control
+path.
+
+QEMU provides two types of vhost-vDPA devices to enable the vDPA device, one
+is type sensitive which means QEMU needs to know the actual device type
+(e.g. net, blk, scsi) and another is called "vhost-vDPA generic device" which
+is type insensitive
+
+The vhost-vDPA generic device builds on the vhost-vdpa subsystem and virtio
+subsystem. It is quite small, but it can support any type of virtio device.
+
+Examples
+--------
+
+Prepare the vhost-vDPA backends first:
+
+::
+  host# ls -l /dev/vhost-vdpa-*
+  crw------- 1 root root 236, 0 Nov  2 00:49 /dev/vhost-vdpa-0
+
+Start QEMU with virtio-mmio bus:
+
+::
+  host# qemu-system                                                  \
+      -M microvm -m 512 -smp 2 -kernel ... -initrd ...               \
+      -device vhost-vdpa-device,vhostdev=/dev/vhost-vdpa-0           \
+      ...
+
+Start QEMU with virtio-pci bus:
+
+::
+  host# qemu-system                                                  \
+      -M pc -m 512 -smp 2                                            \
+      -device vhost-vdpa-device-pci,vhostdev=/dev/vhost-vdpa-0       \
+      ...\
-- 
2.27.0