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

[Longpeng (Mike, Cloud Infrastructure Service Product Dept.)]

在 2022/12/13 22:35, Stefano Garzarella 写道:
> On Mon, Dec 05, 2022 at 04:49:43PM +0800, Longpeng(Mike) wrote:
> > 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
> > --- /dev/null
> > +++ 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.
> > +
>
> Maybe we can also add a minimum requirement section (e.g. we needs at 
> least Linux v5.18 for VHOST_VDPA_GET_VQS_COUNT)
Ok.

> > +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:
> > +
> > +::
>
> Should we add also a `modprobe vhost-vdpa` step?
This is already described in Step 1.

> > +  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
>
> .