Re: [PATCH] vdpa: add driver_override support

[Stefano Garzarella]

On Fri, Nov 05, 2021 at 04:26:44PM +0800, Jason Wang wrote:
> On Fri, Nov 5, 2021 at 4:05 PM Stefano Garzarella <sgarzare@xxxxxxxxxx> wrote:
> > On Fri, Nov 05, 2021 at 11:01:30AM +0800, Jason Wang wrote:
> > >On Fri, Nov 5, 2021 at 12:17 AM Stefano Garzarella <sgarzare@xxxxxxxxxx> wrote:
> > >>
> > >> `driver_override` allows to control which of the vDPA bus drivers
> > >> binds to a vDPA device.
> > >>
> > >> If `driver_override` is not set, the previous behaviour is followed:
> > >> devices use the first vDPA bus driver loaded (unless auto binding
> > >> is disabled).
> > >>
> > >> Tested on Fedora 34 with driverctl(8):
> > >>   $ modprobe virtio-vdpa
> > >>   $ modprobe vhost-vdpa
> > >>   $ modprobe vdpa-sim-net
> > >>
> > >>   $ vdpa dev add mgmtdev vdpasim_net name dev1
> > >>
> > >>   # dev1 is attached to the first vDPA bus driver loaded
> > >>   $ driverctl -b vdpa list-devices
> > >>     dev1 virtio_vdpa
> > >>
> > >>   $ driverctl -b vdpa set-override dev1 vhost_vdpa
> > >>
> > >>   $ driverctl -b vdpa list-devices
> > >>     dev1 vhost_vdpa [*]
> > >>
> > >>   Note: driverctl(8) integrates with udev so the binding is
> > >>   preserved.
> > >>
> > >> Suggested-by: Jason Wang <jasowang@xxxxxxxxxx>
> > >> Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
> > >> ---
> > >>  include/linux/vdpa.h |  2 ++
> > >>  drivers/vdpa/vdpa.c  | 74 ++++++++++++++++++++++++++++++++++++++++++++
> > >>  2 files changed, 76 insertions(+)
> > >>
> > >> diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
> > >> index c3011ccda430..ae34015b37b7 100644
> > >> --- a/include/linux/vdpa.h
> > >> +++ b/include/linux/vdpa.h
> > >> @@ -64,6 +64,7 @@ struct vdpa_mgmt_dev;
> > >>   * struct vdpa_device - representation of a vDPA device
> > >>   * @dev: underlying device
> > >>   * @dma_dev: the actual device that is performing DMA
> > >> + * @driver_override: driver name to force a match
> > >
> > >This seems useless?
> >
> > I'm a bit lost, do you mean we should remove the documentation of
> > `driver_override`?
>
> I misread the code which was misled by vdpa_mgmt_dev above:(

Yeah, the same thing happened to me now while double checking ;-)

> The code should be fine.
>
> So:
>
> Acked-by: Jason Wang <jasowang@xxxxxxxxxx>

Thanks,
Stefano