[Intel-gfx] [PATCH] drm/i915: Explicitly mark Global GTT address spaces

[Chris Wilson]

Quoting Chris Wilson (2018-08-31 16:47:24)
> Quoting Tvrtko Ursulin (2018-08-31 15:36:43)
> > From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> > 
> > So far we have been relying on vm->file pointer being NULL to declare
> > something GGTT.
> > 
> > This has the unfortunate consequence that the default kernel context is
> > also declared GGTT and interferes with the following patch which wants to
> > instantiate VMA's and execute requests against the kernel context.
> > 
> > Change the is_ggtt test to use an explicit flag in struct address_space to
> > solve this issue.
> > 
> > Note that the bit used is free since there is an alignment hole in the
> > struct.
> > 
> > v2:
> >  * Mark mock ggtt.
> > 
> > Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> > Cc: Chris Wilson <chris at chris-wilson.co.uk>
> > ---
> >  drivers/gpu/drm/i915/i915_gem_gtt.c       | 2 ++
> >  drivers/gpu/drm/i915/i915_gem_gtt.h       | 5 ++++-
> >  drivers/gpu/drm/i915/selftests/mock_gtt.c | 2 ++
> >  3 files changed, 8 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> > index d9d44639ba26..eb0e446d6482 100644
> > --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> > +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> > @@ -3604,6 +3604,8 @@ int i915_ggtt_init_hw(struct drm_i915_private *dev_priv)
> >         mutex_lock(&dev_priv->drm.struct_mutex);
> >         i915_address_space_init(&ggtt->vm, dev_priv);
> >  
> > +       ggtt->vm.is_ggtt = true;
> > +
> >         /* Only VLV supports read-only GGTT mappings */
> >         ggtt->vm.has_read_only = IS_VALLEYVIEW(dev_priv);
> >  
> > diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
> > index 01d83a943142..7e2af5f4f39b 100644
> > --- a/drivers/gpu/drm/i915/i915_gem_gtt.h
> > +++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
> > @@ -324,6 +324,9 @@ struct i915_address_space {
> >  
> >         struct pagestash free_pages;
> >  
> > +       /* Global GTT */
> > +       bool is_ggtt:1;
> > +
> >         /* Some systems require uncached updates of the page directories */
> >         bool pt_kmap_wc:1;
> >  
> > @@ -357,7 +360,7 @@ struct i915_address_space {
> >         I915_SELFTEST_DECLARE(bool scrub_64K);
> >  };
> >  
> > -#define i915_is_ggtt(V) (!(V)->file)
> > +#define i915_is_ggtt(vm) ((vm)->is_ggtt)
> 
> But it's so explicit!
> Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>

And pushed, thanks for the patch.
-Chris