Re: [Intel-gfx] [PATCH 1/3] drm/i915: Wrap all access to i915_vma.node.start|size

[Matthew Auld <matthew.william.auld@gmail.com>]

On Fri, 12 Feb 2021 at 10:22, Chris Wilson <chris@chris-wilson.co.uk> wrote:
>
> We already wrap i915_vma.node.start for use with the GGTT, as there we
> can perform additional sanity checks that the node belongs to the GGTT
> and fits within the 32b registers. In the next couple of patches, we
> will introduce guard pages around the objects _inside_ the drm_mm_node
> allocation. That is we will offset the vma->pages so that the first page
> is at drm_mm_node.start + vma->guard (not 0 as is currently the case).
> All users must then not use i915_vma.node.start directly, but compute
> the guard offset, thus all users are converted to use a
> i915_vma_offset() wrapper.
>
> The notable exceptions are the selftests that are testing exact
> behaviour of i915_vma_pin/i915_vma_insert.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---

<snip>

> @@ -562,10 +562,11 @@ void __i915_vma_set_map_and_fenceable(struct i915_vma *vma)
>         GEM_BUG_ON(!i915_vma_is_ggtt(vma));
>         GEM_BUG_ON(!vma->fence_size);
>
> -       fenceable = (vma->node.size >= vma->fence_size &&
> -                    IS_ALIGNED(vma->node.start, vma->fence_alignment));
> +       fenceable = (i915_vma_size(vma) >= vma->fence_size &&
> +                    IS_ALIGNED(i915_vma_offset(vma), vma->fence_alignment));
>
> -       mappable = vma->node.start + vma->fence_size <= i915_vm_to_ggtt(vma->vm)->mappable_end;
> +       mappable = (i915_vma_offset(vma) + vma->fence_size <=
> +                   i915_vm_to_ggtt(vma->vm)->mappable_end);

i915_ggtt_offset(vma) could be used here.

Reviewed-by: Matthew Auld <matthew.auld@intel.com>
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