We rely on page_sizes.sg in setup_scratch_page() reporting the correct value if the underlying sgl is not contiguous, however in get_pages_internal() we are only looking at the layout of the created pages when calculating the sg_page_sizes, and not the final sgl, which could in theory be completely different. In such a situation we might incorrectly think we have a 64K scratch page, when it is actually only 4K or similar split over multiple non-contiguous entries, which could lead to broken behaviour when touching the scratch space within the padding of a 64K GTT page-table. Like we already do for other backends, switch over to calling i915_sg_dma_sizes() after mapping the pages.
Signed-off-by: Matthew Auld <[email protected]> Cc: Andrzej Hajda <[email protected]> --- drivers/gpu/drm/i915/gem/i915_gem_internal.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_internal.c b/drivers/gpu/drm/i915/gem/i915_gem_internal.c index c698f95af15f..301cfb127c4c 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_internal.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_internal.c @@ -36,7 +36,6 @@ static int i915_gem_object_get_pages_internal(struct drm_i915_gem_object *obj) struct drm_i915_private *i915 = to_i915(obj->base.dev); struct sg_table *st; struct scatterlist *sg; - unsigned int sg_page_sizes; unsigned int npages; int max_order; gfp_t gfp; @@ -75,7 +74,6 @@ static int i915_gem_object_get_pages_internal(struct drm_i915_gem_object *obj) sg = st->sgl; st->nents = 0; - sg_page_sizes = 0; do { int order = min(fls(npages) - 1, max_order); @@ -94,7 +92,6 @@ static int i915_gem_object_get_pages_internal(struct drm_i915_gem_object *obj) } while (1); sg_set_page(sg, page, PAGE_SIZE << order, 0); - sg_page_sizes |= PAGE_SIZE << order; st->nents++; npages -= 1 << order; @@ -116,7 +113,7 @@ static int i915_gem_object_get_pages_internal(struct drm_i915_gem_object *obj) goto err; } - __i915_gem_object_set_pages(obj, st, sg_page_sizes); + __i915_gem_object_set_pages(obj, st, i915_sg_dma_sizes(st->sgl)); return 0; -- 2.37.3
