[Intel-gfx] [PATCH v2 12/15] drm/i915/create: apply ALLOC_GPU_ONLY by default

[Matthew Auld]

On Fri, 11 Feb 2022 at 09:49, Thomas Hellström
<thomas.hellstrom at linux.intel.com> wrote:
>
>
> On 2/10/22 13:13, Matthew Auld wrote:
> > Starting from DG2+, when dealing with LMEM, we assume that by default
> > all userspace allocations should be placed in the non-mappable portion
> > of LMEM.  Note that dumb buffers are not included here, since these are
> > not "GPU accelerated" and likely need CPU access.
> >
> > In a later patch userspace will be able to provide a hint if CPU access
> > to the buffer is needed.
> >
> > Signed-off-by: Matthew Auld <matthew.auld at intel.com>
> > Cc: Thomas Hellström <thomas.hellstrom at linux.intel.com>
> > ---
> >   drivers/gpu/drm/i915/gem/i915_gem_create.c | 9 +++++++++
> >   1 file changed, 9 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_create.c b/drivers/gpu/drm/i915/gem/i915_gem_create.c
> > index 9402d4bf4ffc..cc9ddb943f96 100644
> > --- a/drivers/gpu/drm/i915/gem/i915_gem_create.c
> > +++ b/drivers/gpu/drm/i915/gem/i915_gem_create.c
> > @@ -424,6 +424,15 @@ i915_gem_create_ext_ioctl(struct drm_device *dev, void *data,
> >               ext_data.n_placements = 1;
> >       }
> >
> > +     /*
> > +      * TODO: add a userspace hint to force CPU_ACCESS for the object, which
> > +      * can override this.
> > +      */
> > +     if (!IS_DG1(i915) && (ext_data.n_placements > 1 ||
> > +                           ext_data.placements[0]->type !=
> > +                           INTEL_MEMORY_SYSTEM))
> > +             ext_data.flags |= I915_BO_ALLOC_GPU_ONLY;
> > +
>
> WRT previous review comment here, it would be easier to follow if the bo
> was marked as a GPU only buffer regardless. Then for example capture and
> other functions where it actually matters can choose to take action
> based on, for example, whether the BAR is restricted or not?

Yeah, I completely forgot about this, sorry. Will fix now.

>
> /Thomas
>
>
>
> >       obj = __i915_gem_object_create_user_ext(i915, args->size,
> >                                               ext_data.placements,
> >                                               ext_data.n_placements,