[Intel-gfx] [PATCH 1/3] drm/i915: Assert we do not try to expand VMA for hugepage inside GGTT

[Matthew Auld]

On 8 October 2017 at 14:43, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> We only apply the hugepage PD redirection inside the ppGTT, so during
> i915_vma_insert() we want to exclude the GGTT from the additional
> alignment constraints (thereby avoiding the extra GTT pressure from
> fragmentation). Add an assert to document that intention alongside the
> comment.
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Matthew Auld <matthew.william.auld at gmail.com>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_vma.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
> index 72e86b32ab41..2d27027eaf85 100644
> --- a/drivers/gpu/drm/i915/i915_vma.c
> +++ b/drivers/gpu/drm/i915/i915_vma.c
> @@ -513,6 +513,8 @@ i915_vma_insert(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
>                                 rounddown_pow_of_two(vma->page_sizes.sg |
>                                                      I915_GTT_PAGE_SIZE_2M);
>
> +                       GEM_BUG_ON((flags & PIN_USER) == 0); /* No GGTT! */
> +
Maybe GEM_BUG_ON(i915_is_ggtt(vm)); should also catch misuse with the appgtt?

Either way:
Reviewed-by: Matthew Auld <matthew.william.auld at gmail.com>