> From: Michael S. Tsirkin <[email protected]>
> Sent: Thursday, October 28, 2021 1:46 AM
>
> On Wed, Oct 27, 2021 at 03:21:15PM +0000, Parav Pandit wrote:
> > Hi Stefano,
> >
> > > From: Stefano Garzarella <[email protected]>
> > > Sent: Wednesday, October 27, 2021 8:04 PM
> > >
> > > Hi folks,
> > > I was trying to understand if we have a way to specify which vDPA
> > > bus driver (e.g. vhost-vdpa, virtio-vdpa) a device should use.
> > > IIUC we don't have it, and the first registered driver is used when
> > > a new device is registered.
> > >
> > > I was thinking if it makes sense to extend the management API to
> > > specify which bus driver to use for a device. A use case could be
> > > for example a single host handling VMs and bare-metal containers, so
> > > we would have both virtio-vdpa and vhost-vdpa loaded and we want to
> > > attach some devices to VMs through vhost-vdpa and others to containers
> through virtio-vdpa.
> > >
> > > What do you think?
> > >
> > One option is, user keeps the drivers_autoprobe disabled for the vdpa
> > bus using,
> >
> > $ vdpa/vdpa dev add mgmtdev vdpasim_net name vdpa0 mac
> > 00:11:22:33:44:55 $ echo 0 > /sys/bus/vdpa/drivers_autoprobe
> >
> > And after vdpa device creation, it manually binds to the desired
> > driver such as,
> >
> > $ echo vdpa0 > /sys/bus/vdpa/drivers/virtio_vdpa/bind
> > Or
> > $ echo vdpa0 > /sys/bus/vdpa/drivers/vhost_vdpa/bind
> >
> > In an case of VDUSE, it makes more sense to bind to the one of the above
> driver after user space has connected the use space backend to the kernel
> device.
>
> The only annoying thing is that manual bind is not validated.
> E.g. if one makes a mistake and binds an incorrect device, it just tends to
> crash
> IIRC.
Only a vdpa device can be bind/unbind to a vdpa bus driver.
Such checks are done by the kernel core.
I didn't follow when can it crash. Can you please share an example when can it
crash?
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