drm/i915: use i915_sg_dma_sizes() for all backends

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. For most of the other backends we
already just call i915_sg_dma_sizes() on the final mapping, so rather
just move that into __i915_gem_object_set_pages() to avoid such issues
coming back to bite us later.

v2: Update missing conversion in gvt
Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Stuart Summers <stuart.summers@intel.com>
Cc: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221108103238.165447-1-matthew.auld@intel.com

drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c

@@ -238,7 +238,6 @@ static int i915_gem_object_get_pages_dmabuf(struct drm_i915_gem_object *obj)
 {
 	struct drm_i915_private *i915 = to_i915(obj->base.dev);
 	struct sg_table *sgt;
-	unsigned int sg_page_sizes;
 
 	assert_object_held(obj);
 
@@ -262,8 +261,7 @@ static int i915_gem_object_get_pages_dmabuf(struct drm_i915_gem_object *obj)
 	    (!HAS_LLC(i915) && !IS_DG1(i915)))
 		wbinvd_on_all_cpus();
 
-	sg_page_sizes = i915_sg_dma_sizes(sgt->sgl);
-	__i915_gem_object_set_pages(obj, sgt, sg_page_sizes);
+	__i915_gem_object_set_pages(obj, sgt);
 
 	return 0;
 }

drivers/gpu/drm/i915/gem/i915_gem_internal.c

@@ -35,7 +35,6 @@ 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 = MAX_ORDER;
 	unsigned int max_segment;
@@ -64,7 +63,6 @@ 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);
@@ -83,7 +81,6 @@ 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;
@@ -105,7 +102,7 @@ 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);
 
 	return 0;
 

drivers/gpu/drm/i915/gem/i915_gem_object.h

@@ -403,8 +403,7 @@ i915_gem_object_get_dma_address(struct drm_i915_gem_object *obj,
 				unsigned long n);
 
 void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj,
-				 struct sg_table *pages,
-				 unsigned int sg_page_sizes);
+				 struct sg_table *pages);
 
 int ____i915_gem_object_get_pages(struct drm_i915_gem_object *obj);
 int __i915_gem_object_get_pages(struct drm_i915_gem_object *obj);

drivers/gpu/drm/i915/gem/i915_gem_pages.c

@@ -16,8 +16,7 @@
 #include "i915_gem_mman.h"
 
 void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj,
-				 struct sg_table *pages,
-				 unsigned int sg_page_sizes)
+				 struct sg_table *pages)
 {
 	struct drm_i915_private *i915 = to_i915(obj->base.dev);
 	unsigned long supported = RUNTIME_INFO(i915)->page_sizes;
@@ -45,8 +44,8 @@ void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj,
 
 	obj->mm.pages = pages;
 
-	GEM_BUG_ON(!sg_page_sizes);
-	obj->mm.page_sizes.phys = sg_page_sizes;
+	obj->mm.page_sizes.phys = i915_sg_dma_sizes(pages->sgl);
+	GEM_BUG_ON(!obj->mm.page_sizes.phys);
 
 	/*
 	 * Calculate the supported page-sizes which fit into the given

drivers/gpu/drm/i915/gem/i915_gem_phys.c

@@ -79,7 +79,7 @@ static int i915_gem_object_get_pages_phys(struct drm_i915_gem_object *obj)
 
 	/* We're no longer struct page backed */
 	obj->mem_flags &= ~I915_BO_FLAG_STRUCT_PAGE;
-	__i915_gem_object_set_pages(obj, st, sg->length);
+	__i915_gem_object_set_pages(obj, st);
 
 	return 0;
 
@@ -209,11 +209,8 @@ static int i915_gem_object_shmem_to_phys(struct drm_i915_gem_object *obj)
 	return 0;
 
 err_xfer:
-	if (!IS_ERR_OR_NULL(pages)) {
-		unsigned int sg_page_sizes = i915_sg_dma_sizes(pages->sgl);
-
-		__i915_gem_object_set_pages(obj, pages, sg_page_sizes);
-	}
+	if (!IS_ERR_OR_NULL(pages))
+		__i915_gem_object_set_pages(obj, pages);
 	return err;
 }
 

drivers/gpu/drm/i915/gem/i915_gem_shmem.c

@@ -247,7 +247,7 @@ static int shmem_get_pages(struct drm_i915_gem_object *obj)
 	if (i915_gem_object_can_bypass_llc(obj))
 		obj->cache_dirty = true;
 
-	__i915_gem_object_set_pages(obj, st, i915_sg_dma_sizes(st->sgl));
+	__i915_gem_object_set_pages(obj, st);
 
 	return 0;
 

drivers/gpu/drm/i915/gem/i915_gem_stolen.c

@@ -628,7 +628,7 @@ static int i915_gem_object_get_pages_stolen(struct drm_i915_gem_object *obj)
 		   sg_dma_len(pages->sgl),
 		   POISON_INUSE);
 
-	__i915_gem_object_set_pages(obj, pages, obj->stolen->size);
+	__i915_gem_object_set_pages(obj, pages);
 
 	return 0;
 }

drivers/gpu/drm/i915/gem/i915_gem_ttm.c

@@ -815,8 +815,7 @@ static int __i915_ttm_get_pages(struct drm_i915_gem_object *obj,
 
 		GEM_BUG_ON(obj->mm.rsgt);
 		obj->mm.rsgt = rsgt;
-		__i915_gem_object_set_pages(obj, &rsgt->table,
-					    i915_sg_dma_sizes(rsgt->table.sgl));
+		__i915_gem_object_set_pages(obj, &rsgt->table);
 	}
 
 	GEM_BUG_ON(bo->ttm && ((obj->base.size >> PAGE_SHIFT) < bo->ttm->num_pages));

drivers/gpu/drm/i915/gem/i915_gem_userptr.c

@@ -131,7 +131,6 @@ static int i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj)
 	const unsigned long num_pages = obj->base.size >> PAGE_SHIFT;
 	unsigned int max_segment = i915_sg_segment_size(obj->base.dev->dev);
 	struct sg_table *st;
-	unsigned int sg_page_sizes;
 	struct page **pvec;
 	int ret;
 
@@ -170,8 +169,7 @@ static int i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj)
 	if (i915_gem_object_can_bypass_llc(obj))
 		obj->cache_dirty = true;
 
-	sg_page_sizes = i915_sg_dma_sizes(st->sgl);
-	__i915_gem_object_set_pages(obj, st, sg_page_sizes);
+	__i915_gem_object_set_pages(obj, st);
 
 	return 0;
 

drivers/gpu/drm/i915/gem/selftests/huge_gem_object.c

@@ -68,7 +68,7 @@ static int huge_get_pages(struct drm_i915_gem_object *obj)
 	if (i915_gem_gtt_prepare_pages(obj, pages))
 		goto err;
 
-	__i915_gem_object_set_pages(obj, pages, PAGE_SIZE);
+	__i915_gem_object_set_pages(obj, pages);
 
 	return 0;
 

drivers/gpu/drm/i915/gem/selftests/huge_pages.c

@@ -136,7 +136,7 @@ static int get_huge_pages(struct drm_i915_gem_object *obj)
 		goto err;
 
 	GEM_BUG_ON(sg_page_sizes != obj->mm.page_mask);
-	__i915_gem_object_set_pages(obj, st, sg_page_sizes);
+	__i915_gem_object_set_pages(obj, st);
 
 	return 0;
 
@@ -210,7 +210,6 @@ static int fake_get_huge_pages(struct drm_i915_gem_object *obj)
 	const u64 max_len = rounddown_pow_of_two(UINT_MAX);
 	struct sg_table *st;
 	struct scatterlist *sg;
-	unsigned int sg_page_sizes;
 	u64 rem;
 
 	st = kmalloc(sizeof(*st), GFP);
@@ -226,7 +225,6 @@ static int fake_get_huge_pages(struct drm_i915_gem_object *obj)
 	rem = obj->base.size;
 	sg = st->sgl;
 	st->nents = 0;
-	sg_page_sizes = 0;
 	do {
 		unsigned int page_size = get_largest_page_size(i915, rem);
 		unsigned int len = min(page_size * div_u64(rem, page_size),
@@ -239,8 +237,6 @@ static int fake_get_huge_pages(struct drm_i915_gem_object *obj)
 		sg_dma_len(sg) = len;
 		sg_dma_address(sg) = page_size;
 
-		sg_page_sizes |= len;
-
 		st->nents++;
 
 		rem -= len;
@@ -254,7 +250,7 @@ static int fake_get_huge_pages(struct drm_i915_gem_object *obj)
 
 	i915_sg_trim(st);
 
-	__i915_gem_object_set_pages(obj, st, sg_page_sizes);
+	__i915_gem_object_set_pages(obj, st);
 
 	return 0;
 }
@@ -286,7 +282,7 @@ static int fake_get_huge_pages_single(struct drm_i915_gem_object *obj)
 	sg_dma_len(sg) = obj->base.size;
 	sg_dma_address(sg) = page_size;
 
-	__i915_gem_object_set_pages(obj, st, sg->length);
+	__i915_gem_object_set_pages(obj, st);
 
 	return 0;
 #undef GFP

drivers/gpu/drm/i915/gvt/dmabuf.c

@@ -88,7 +88,7 @@ static int vgpu_gem_get_pages(
 		sg_dma_address(sg) = dma_addr;
 	}
 
-	__i915_gem_object_set_pages(obj, st, PAGE_SIZE);
+	__i915_gem_object_set_pages(obj, st);
 out:
 	if (ret) {
 		dma_addr_t dma_addr;

drivers/gpu/drm/i915/selftests/i915_gem_gtt.c

@@ -61,7 +61,6 @@ static int fake_get_pages(struct drm_i915_gem_object *obj)
 #define PFN_BIAS 0x1000
 	struct sg_table *pages;
 	struct scatterlist *sg;
-	unsigned int sg_page_sizes;
 	typeof(obj->base.size) rem;
 
 	pages = kmalloc(sizeof(*pages), GFP);
@@ -74,7 +73,6 @@ static int fake_get_pages(struct drm_i915_gem_object *obj)
 		return -ENOMEM;
 	}
 
-	sg_page_sizes = 0;
 	rem = obj->base.size;
 	for (sg = pages->sgl; sg; sg = sg_next(sg)) {
 		unsigned long len = min_t(typeof(rem), rem, BIT(31));
@@ -83,13 +81,12 @@ static int fake_get_pages(struct drm_i915_gem_object *obj)
 		sg_set_page(sg, pfn_to_page(PFN_BIAS), len, 0);
 		sg_dma_address(sg) = page_to_phys(sg_page(sg));
 		sg_dma_len(sg) = len;
-		sg_page_sizes |= len;
 
 		rem -= len;
 	}
 	GEM_BUG_ON(rem);
 
-	__i915_gem_object_set_pages(obj, pages, sg_page_sizes);
+	__i915_gem_object_set_pages(obj, pages);
 
 	return 0;
 #undef GFP

drivers/gpu/drm/i915/selftests/mock_region.c

@@ -41,7 +41,7 @@ static int mock_region_get_pages(struct drm_i915_gem_object *obj)
 	}
 
 	pages = &obj->mm.rsgt->table;
-	__i915_gem_object_set_pages(obj, pages, i915_sg_dma_sizes(pages->sgl));
+	__i915_gem_object_set_pages(obj, pages);
 
 	return 0;