On Mon, Jun 22, 2020 at 4:22 PM Pekka Paalanen <ppaalanen@xxxxxxxxx> wrote:
>
> On Mon, 22 Jun 2020 11:35:01 +0200
> Daniel Vetter <daniel@xxxxxxxx> wrote:
>
> > On Sun, Jun 21, 2020 at 02:03:01AM -0400, Andrey Grodzovsky wrote:
> > > Will be used to reroute CPU mapped BO's page faults once
> > > device is removed.
> > >
> > > Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@xxxxxxx>
> > > ---
> > > drivers/gpu/drm/drm_file.c | 8 ++++++++
> > > drivers/gpu/drm/drm_prime.c | 10 ++++++++++
> > > include/drm/drm_file.h | 2 ++
> > > include/drm/drm_gem.h | 2 ++
> > > 4 files changed, 22 insertions(+)
>
> ...
>
> > > diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
> > > index 0b37506..47460d1 100644
> > > --- a/include/drm/drm_gem.h
> > > +++ b/include/drm/drm_gem.h
> > > @@ -310,6 +310,8 @@ struct drm_gem_object {
> > > *
> > > */
> > > const struct drm_gem_object_funcs *funcs;
> > > +
> > > + struct page *dummy_page;
> > > };
> >
> > I think amdgpu doesn't care, but everyone else still might care somewhat
> > about flink. That also shares buffers, so also needs to allocate the
> > per-bo dummy page.
>
> Do you really care about making flink not explode on device
> hot-unplug? Why not just leave flink users die in a fire?
> It's not a regression.
It's not about exploding, they won't. With flink you can pass a buffer
from one address space to the other, so imo we should avoid false
sharing. E.g. if you happen to write something $secret into a private
buffer, but only $non-secret stuff into shared buffers. Then if you
unplug, your well-kept $secret might suddenly be visible by lots of
other processes you never intended to share it with.
Just feels safer to plug that hole completely.
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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