Re: [RFC PATCH 1/6] vdpa: add bind_mm callback

[Stefano Garzarella]

On Fri, Dec 16, 2022 at 02:37:45PM +0800, Jason Wang wrote:
> On Thu, Dec 15, 2022 at 12:30 AM Stefano Garzarella <sgarzare@xxxxxxxxxx> wrote:
> > This new optional callback is used to bind the device to a specific
> > address space so the vDPA framework can use VA when this callback
> > is implemented.
> >
> > Suggested-by: Jason Wang <jasowang@xxxxxxxxxx>
> > Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
> > ---
> >  include/linux/vdpa.h | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> >
> > diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
> > index 6d0f5e4e82c2..34388e21ef3f 100644
> > --- a/include/linux/vdpa.h
> > +++ b/include/linux/vdpa.h
> > @@ -282,6 +282,12 @@ struct vdpa_map_file {
> >   *                             @iova: iova to be unmapped
> >   *                             @size: size of the area
> >   *                             Returns integer: success (0) or error (< 0)
> > + * @bind_mm:                   Bind the device to a specific address space
> > + *                             so the vDPA framework can use VA when this
> > + *                             callback is implemented. (optional)
> > + *                             @vdev: vdpa device
> > + *                             @mm: address space to bind
>
> Do we need an unbind or did a NULL mm mean unbind?

Yep, your comment in patch 6 makes it necessary. I will add it!

> > + *                             @owner: process that owns the address space
>
> Any reason we need the task_struct here?

Mainly to attach to kthread to the process cgroups, but that part is 
still in TODO since I need to understand it better.

Maybe we can remove the task_struct here and use `current` directly in 
the callback.

Thanks,
Stefano