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drm/i915/ttm: fix sg_table construction

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If we encounter some monster sized local-memory page that exceeds the
maximum sg length (UINT32_MAX), ensure that don't end up with some
misaligned address in the entry that follows, leading to fireworks
later. Also ensure we have some coverage of this in the selftests.

v2(Chris):
  - Use round_down consistently to avoid udiv errors
v3(Nirmoy):
  - Also update the max_segment in the selftest

Fixes: f701b16d4c ("drm/i915/ttm: add i915_sg_from_buddy_resource")
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/6379
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Nirmoy Das <nirmoy.das@linux.intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220711085859.24198-1-matthew.auld@intel.com
(cherry picked from commit bc99f1209f)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
This commit is contained in:
Matthew Auld 2022-07-11 09:58:59 +01:00 committed by Rodrigo Vivi
parent 896dcabd1f
commit aff1e0b09b
7 changed files with 58 additions and 15 deletions
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11
drivers/gpu/drm/i915/gem/i915_gem_ttm.c
View File

@ -620,10 +620,15 @@ i915_ttm_resource_get_st(struct drm_i915_gem_object *obj,
struct ttm_resource *res)
{
struct ttm_buffer_object *bo = i915_gem_to_ttm(obj);
u64 page_alignment;
if (!i915_ttm_gtt_binds_lmem(res))
return i915_ttm_tt_get_st(bo->ttm);
page_alignment = bo->page_alignment << PAGE_SHIFT;
if (!page_alignment)
page_alignment = obj->mm.region->min_page_size;
/*
* If CPU mapping differs, we need to add the ttm_tt pages to
* the resulting st. Might make sense for GGTT.
@ -634,7 +639,8 @@ i915_ttm_resource_get_st(struct drm_i915_gem_object *obj,
struct i915_refct_sgt *rsgt;
rsgt = intel_region_ttm_resource_to_rsgt(obj->mm.region,
res);
res,
page_alignment);
if (IS_ERR(rsgt))
return rsgt;
@ -643,7 +649,8 @@ i915_ttm_resource_get_st(struct drm_i915_gem_object *obj,
return i915_refct_sgt_get(obj->ttm.cached_io_rsgt);
}
return intel_region_ttm_resource_to_rsgt(obj->mm.region, res);
return intel_region_ttm_resource_to_rsgt(obj->mm.region, res,
page_alignment);
}
static int i915_ttm_truncate(struct drm_i915_gem_object *obj)

19
drivers/gpu/drm/i915/i915_scatterlist.c
View File

@ -68,6 +68,7 @@ void i915_refct_sgt_init(struct i915_refct_sgt *rsgt, size_t size)
* drm_mm_node
* @node: The drm_mm_node.
* @region_start: An offset to add to the dma addresses of the sg list.
* @page_alignment: Required page alignment for each sg entry. Power of two.
*
* Create a struct sg_table, initializing it from a struct drm_mm_node,
* taking a maximum segment length into account, splitting into segments
@ -77,15 +78,18 @@ void i915_refct_sgt_init(struct i915_refct_sgt *rsgt, size_t size)
* error code cast to an error pointer on failure.
*/
struct i915_refct_sgt *i915_rsgt_from_mm_node(const struct drm_mm_node *node,
u64 region_start)
u64 region_start,
u64 page_alignment)
{
const u64 max_segment = SZ_1G; /* Do we have a limit on this? */
const u64 max_segment = round_down(UINT_MAX, page_alignment);
u64 segment_pages = max_segment >> PAGE_SHIFT;
u64 block_size, offset, prev_end;
struct i915_refct_sgt *rsgt;
struct sg_table *st;
struct scatterlist *sg;
GEM_BUG_ON(!max_segment);
rsgt = kmalloc(sizeof(*rsgt), GFP_KERNEL);
if (!rsgt)
return ERR_PTR(-ENOMEM);
@ -112,6 +116,8 @@ struct i915_refct_sgt *i915_rsgt_from_mm_node(const struct drm_mm_node *node,
sg = __sg_next(sg);
sg_dma_address(sg) = region_start + offset;
GEM_BUG_ON(!IS_ALIGNED(sg_dma_address(sg),
page_alignment));
sg_dma_len(sg) = 0;
sg->length = 0;
st->nents++;
@ -138,6 +144,7 @@ struct i915_refct_sgt *i915_rsgt_from_mm_node(const struct drm_mm_node *node,
* i915_buddy_block list
* @res: The struct i915_ttm_buddy_resource.
* @region_start: An offset to add to the dma addresses of the sg list.
* @page_alignment: Required page alignment for each sg entry. Power of two.
*
* Create a struct sg_table, initializing it from struct i915_buddy_block list,
* taking a maximum segment length into account, splitting into segments
@ -147,11 +154,12 @@ struct i915_refct_sgt *i915_rsgt_from_mm_node(const struct drm_mm_node *node,
* error code cast to an error pointer on failure.
*/
struct i915_refct_sgt *i915_rsgt_from_buddy_resource(struct ttm_resource *res,
u64 region_start)
u64 region_start,
u64 page_alignment)
{
struct i915_ttm_buddy_resource *bman_res = to_ttm_buddy_resource(res);
const u64 size = res->num_pages << PAGE_SHIFT;
const u64 max_segment = rounddown(UINT_MAX, PAGE_SIZE);
const u64 max_segment = round_down(UINT_MAX, page_alignment);
struct drm_buddy *mm = bman_res->mm;
struct list_head *blocks = &bman_res->blocks;
struct drm_buddy_block *block;
@ -161,6 +169,7 @@ struct i915_refct_sgt *i915_rsgt_from_buddy_resource(struct ttm_resource *res,
resource_size_t prev_end;
GEM_BUG_ON(list_empty(blocks));
GEM_BUG_ON(!max_segment);
rsgt = kmalloc(sizeof(*rsgt), GFP_KERNEL);
if (!rsgt)
@ -191,6 +200,8 @@ struct i915_refct_sgt *i915_rsgt_from_buddy_resource(struct ttm_resource *res,
sg = __sg_next(sg);
sg_dma_address(sg) = region_start + offset;
GEM_BUG_ON(!IS_ALIGNED(sg_dma_address(sg),
page_alignment));
sg_dma_len(sg) = 0;
sg->length = 0;
st->nents++;

6
drivers/gpu/drm/i915/i915_scatterlist.h
View File

@ -213,9 +213,11 @@ static inline void __i915_refct_sgt_init(struct i915_refct_sgt *rsgt,
void i915_refct_sgt_init(struct i915_refct_sgt *rsgt, size_t size);
struct i915_refct_sgt *i915_rsgt_from_mm_node(const struct drm_mm_node *node,
u64 region_start);
u64 region_start,
u64 page_alignment);
struct i915_refct_sgt *i915_rsgt_from_buddy_resource(struct ttm_resource *res,
u64 region_start);
u64 region_start,
u64 page_alignment);
#endif

10
drivers/gpu/drm/i915/intel_region_ttm.c
View File

@ -152,6 +152,7 @@ int intel_region_ttm_fini(struct intel_memory_region *mem)
* Convert an opaque TTM resource manager resource to a refcounted sg_table.
* @mem: The memory region.
* @res: The resource manager resource obtained from the TTM resource manager.
* @page_alignment: Required page alignment for each sg entry. Power of two.
*
* The gem backends typically use sg-tables for operations on the underlying
* io_memory. So provide a way for the backends to translate the
@ -161,16 +162,19 @@ int intel_region_ttm_fini(struct intel_memory_region *mem)
*/
struct i915_refct_sgt *
intel_region_ttm_resource_to_rsgt(struct intel_memory_region *mem,
struct ttm_resource *res)
struct ttm_resource *res,
u64 page_alignment)
{
if (mem->is_range_manager) {
struct ttm_range_mgr_node *range_node =
to_ttm_range_mgr_node(res);
return i915_rsgt_from_mm_node(&range_node->mm_nodes[0],
mem->region.start);
mem->region.start,
page_alignment);
} else {
return i915_rsgt_from_buddy_resource(res, mem->region.start);
return i915_rsgt_from_buddy_resource(res, mem->region.start,
page_alignment);
}
}

3
drivers/gpu/drm/i915/intel_region_ttm.h
View File

@ -24,7 +24,8 @@ int intel_region_ttm_fini(struct intel_memory_region *mem);
struct i915_refct_sgt *
intel_region_ttm_resource_to_rsgt(struct intel_memory_region *mem,
struct ttm_resource *res);
struct ttm_resource *res,
u64 page_alignment);
void intel_region_ttm_resource_free(struct intel_memory_region *mem,
struct ttm_resource *res);

21
drivers/gpu/drm/i915/selftests/intel_memory_region.c
View File

@ -451,7 +451,6 @@ out_put:
static int igt_mock_max_segment(void *arg)
{
const unsigned int max_segment = rounddown(UINT_MAX, PAGE_SIZE);
struct intel_memory_region *mem = arg;
struct drm_i915_private *i915 = mem->i915;
struct i915_ttm_buddy_resource *res;
@ -460,7 +459,10 @@ static int igt_mock_max_segment(void *arg)
struct drm_buddy *mm;
struct list_head *blocks;
struct scatterlist *sg;
I915_RND_STATE(prng);
LIST_HEAD(objects);
unsigned int max_segment;
unsigned int ps;
u64 size;
int err = 0;
@ -472,7 +474,13 @@ static int igt_mock_max_segment(void *arg)
*/
size = SZ_8G;
mem = mock_region_create(i915, 0, size, PAGE_SIZE, 0, 0);
ps = PAGE_SIZE;
if (i915_prandom_u64_state(&prng) & 1)
ps = SZ_64K; /* For something like DG2 */
max_segment = round_down(UINT_MAX, ps);
mem = mock_region_create(i915, 0, size, ps, 0, 0);
if (IS_ERR(mem))
return PTR_ERR(mem);
@ -498,12 +506,21 @@ static int igt_mock_max_segment(void *arg)
}
for (sg = obj->mm.pages->sgl; sg; sg = sg_next(sg)) {
dma_addr_t daddr = sg_dma_address(sg);
if (sg->length > max_segment) {
pr_err("%s: Created an oversized scatterlist entry, %u > %u\n",
__func__, sg->length, max_segment);
err = -EINVAL;
goto out_close;
}
if (!IS_ALIGNED(daddr, ps)) {
pr_err("%s: Created an unaligned scatterlist entry, addr=%pa, ps=%u\n",
__func__, &daddr, ps);
err = -EINVAL;
goto out_close;
}
}
out_close:

3
drivers/gpu/drm/i915/selftests/mock_region.c
View File

@ -33,7 +33,8 @@ static int mock_region_get_pages(struct drm_i915_gem_object *obj)
return PTR_ERR(obj->mm.res);
obj->mm.rsgt = intel_region_ttm_resource_to_rsgt(obj->mm.region,
obj->mm.res);
obj->mm.res,
obj->mm.region->min_page_size);
if (IS_ERR(obj->mm.rsgt)) {
err = PTR_ERR(obj->mm.rsgt);
goto err_free_resource;