[PATCH v10 5/5] docs: Add generic vhost-vdpa device documentation

["Longpeng(Mike)" via <qemu-devel@nongnu.org>]

From: Longpeng <longpeng2@huawei.com>

Signed-off-by: Longpeng <longpeng2@huawei.com>
---
 .../devices/vhost-vdpa-generic-device.rst     | 66 +++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 docs/system/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..7d13359ea1
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+++ b/docs/system/devices/vhost-vdpa-generic-device.rst
@@ -0,0 +1,66 @@
+
+=========================
+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
+--------
+
+1. Please make sure the modules listed bellow are installed:
+    vhost.ko
+    vhost_iotlb.ko
+    vdpa.ko
+    vhost_vdpa.ko
+
+
+2. Prepare the vhost-vDPA backends, here is an example using vdpa_sim_blk
+   device:
+
+::
+  host# modprobe vdpa_sim_blk
+  host# vdpa dev add mgmtdev vdpasim_blk name blk0
+  (...you can see the vhost-vDPA device under /dev directory now...)
+  host# ls -l /dev/vhost-vdpa-*
+  crw------- 1 root root 236, 0 Nov  2 00:49 /dev/vhost-vdpa-0
+
+Note:
+It needs some vendor-specific steps to provision the vDPA device if you're
+using real HW devices, such as installing the vendor-specific vDPA driver
+and binding the device to the driver.
+
+
+3. Start the virtual machine:
+
+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       \
+      ...
-- 
2.23.0