[Intel-gfx] [PATCH xf86-video-intel] SNA: fix PRIME output support since xserver 1.20

[Peter Wu]

In meantime this patch has been picked up by the Arch Linux packages:
https://bugs.archlinux.org/task/58895

Is there any chance that this patch can be reviewed/applied? The diff is
quite small and should be easy to review.

On Wed, Aug 29, 2018 at 12:22:21PM +0200, Peter Wu wrote:
> Ping.
> 
> This patch was independently verified working (see the linked bug
> report) and is essential for Xorg 1.20 using this driver.
> 
> On Tue, Aug 14, 2018 at 02:16:07AM +0200, Peter Wu wrote:
> > Since xorg-server 1.20, an external monitor would remain blank when used
> > in a PRIME output slave setup. Only a cursor was visible. The cause is
> > "Make PixmapDirtyUpdateRec::src a DrawablePtr" in xserver, the "src"
> > pointer might point to the root window (created by the server) instead
> > of a pixmap (as created by xf86-video-intel). Use get_drawable_pixmap to
> > handle both cases.
> > 
> > When built with -fsanitize=address, the following test will trigger a
> > heap-buffer-overflow error due to to_sna_from_pixmap receiving a window
> > instead of a pixmap.
> > 
> > Test on a hybrid graphics laptop (Intel + modesetting/nouveau):
> > 
> >     xrandr --setprovideroutputsource modesetting Intel
> >     xrandr --output DP-1-1 --mode 2560x1440  # should not crash
> >     glxgears  # should display gears on both screens
> > 
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100086
> > Signed-off-by: Peter Wu <peter at lekensteyn.nl>
> > ---
> > Tested with xserver 1.20.1 with ASAN enabled. Survives multiple
> > resolution changes, works with a Plasma desktop session, it seems
> > stable. Something like this patch is required to make multi-monitor
> > setups usable in a hybrid graphics setting with Xorg 1.20.
> > ---
> >  src/sna/sna_accel.c | 18 ++++++++++++++++++
> >  1 file changed, 18 insertions(+)
> > 
> > diff --git a/src/sna/sna_accel.c b/src/sna/sna_accel.c
> > index 2f669bcf..80b116a3 100644
> > --- a/src/sna/sna_accel.c
> > +++ b/src/sna/sna_accel.c
> > @@ -17510,7 +17510,11 @@ static bool has_offload_slaves(struct sna *sna)
> >  	PixmapDirtyUpdatePtr dirty;
> >  
> >  	xorg_list_for_each_entry(dirty, &screen->pixmap_dirty_list, ent) {
> > +#ifdef HAS_DIRTYTRACKING_DRAWABLE_SRC
> > +		assert(dirty->src == &sna->front->drawable);
> > +#else
> >  		assert(dirty->src == sna->front);
> > +#endif
> >  		if (RegionNotEmpty(DamageRegion(dirty->damage)))
> >  			return true;
> >  	}
> > @@ -17671,7 +17675,11 @@ static void sna_accel_post_damage(struct sna *sna)
> >  		if (RegionNil(damage))
> >  			continue;
> >  
> > +#ifdef HAS_DIRTYTRACKING_DRAWABLE_SRC
> > +		src = get_drawable_pixmap(dirty->src);
> > +#else
> >  		src = dirty->src;
> > +#endif
> >  		dst = dirty->slave_dst->master_pixmap;
> >  
> >  		region.extents.x1 = dirty->x;
> > @@ -17922,9 +17930,15 @@ migrate_dirty_tracking(PixmapPtr old_front, PixmapPtr new_front)
> >  	PixmapDirtyUpdatePtr dirty, safe;
> >  
> >  	xorg_list_for_each_entry_safe(dirty, safe, &screen->pixmap_dirty_list, ent) {
> > +#ifdef HAS_DIRTYTRACKING_DRAWABLE_SRC
> > +		assert(dirty->src == &old_front->drawable);
> > +		if (dirty->src != &old_front->drawable)
> > +			continue;
> > +#else
> >  		assert(dirty->src == old_front);
> >  		if (dirty->src != old_front)
> >  			continue;
> > +#endif
> >  
> >  		DamageUnregister(&dirty->src->drawable, dirty->damage);
> >  		DamageDestroy(dirty->damage);
> > @@ -17939,7 +17953,11 @@ migrate_dirty_tracking(PixmapPtr old_front, PixmapPtr new_front)
> >  		}
> >  
> >  		DamageRegister(&new_front->drawable, dirty->damage);
> > +#ifdef HAS_DIRTYTRACKING_DRAWABLE_SRC
> > +		dirty->src = &new_front->drawable;
> > +#else
> >  		dirty->src = new_front;
> > +#endif
> >  	}
> >  #endif
> >  }
> > -- 
> > 2.18.0