Quoting Chris Wilson (2018-08-31 16:47:24)
> Quoting Tvrtko Ursulin (2018-08-31 15:36:43)
> > From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> >
> > 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@xxxxxxxxx>
> > Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> > ---
> > 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@xxxxxxxxxxxxxxxxxx>
And pushed, thanks for the patch.
-Chris
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