[PATCH 5.18 101/231] drm/i915/ttm: fix sg_table construction

Greg Kroah-Hartman
2022-07-19T12:57:46Z

From: Matthew Auld <matthew.auld@intel.com>

[ Upstream commit aff1e0b09b54b64944b7fe32997229552737b9e9 ]

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: f701b16d4cc5 ("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 bc99f1209f19fefa3ee11e77464ccfae541f4291)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 11 ++++++++--
drivers/gpu/drm/i915/i915_scatterlist.c | 19 +++++++++++++----
drivers/gpu/drm/i915/i915_scatterlist.h | 6 ++++--
drivers/gpu/drm/i915/intel_region_ttm.c | 10 ++++++---
drivers/gpu/drm/i915/intel_region_ttm.h | 3 ++-
.../drm/i915/selftests/intel_memory_region.c | 21 +++++++++++++++++--
drivers/gpu/drm/i915/selftests/mock_region.c | 3 ++-
7 files changed, 58 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
index 45cc5837ce00..342ca303eae4 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
@@ -583,10 +583,15 @@ 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.
@@ -597,7 +602,8 @@ 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;

@@ -606,7 +612,8 @@ 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)
diff --git a/drivers/gpu/drm/i915/i915_scatterlist.c b/drivers/gpu/drm/i915/i915_scatterlist.c
index 159571b9bd24..f63b50b71e10 100644
--- a/drivers/gpu/drm/i915/i915_scatterlist.c
+++ b/drivers/gpu/drm/i915/i915_scatterlist.c
@@ -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++;
diff --git a/drivers/gpu/drm/i915/i915_scatterlist.h b/drivers/gpu/drm/i915/i915_scatterlist.h
index 12c6a1684081..b13e4cdea923 100644
--- a/drivers/gpu/drm/i915/i915_scatterlist.h
+++ b/drivers/gpu/drm/i915/i915_scatterlist.h
@@ -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
diff --git a/drivers/gpu/drm/i915/intel_region_ttm.c b/drivers/gpu/drm/i915/intel_region_ttm.c
index 737ef3f4ab54..d896558cf458 100644
--- a/drivers/gpu/drm/i915/intel_region_ttm.c
+++ b/drivers/gpu/drm/i915/intel_region_ttm.c
@@ -151,6 +151,7 @@ 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
@@ -160,16 +161,19 @@ 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);
}
}

diff --git a/drivers/gpu/drm/i915/intel_region_ttm.h b/drivers/gpu/drm/i915/intel_region_ttm.h
index fdee5e7bd46c..b17e494ef79c 100644
--- a/drivers/gpu/drm/i915/intel_region_ttm.h
+++ b/drivers/gpu/drm/i915/intel_region_ttm.h
@@ -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);
diff --git a/drivers/gpu/drm/i915/selftests/intel_memory_region.c b/drivers/gpu/drm/i915/selftests/intel_memory_region.c
index ba32893e0873..0250a114fe0a 100644
--- a/drivers/gpu/drm/i915/selftests/intel_memory_region.c
+++ b/drivers/gpu/drm/i915/selftests/intel_memory_region.c
@@ -451,7 +451,6 @@ static int igt_mock_splintered_region(void *arg)

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:
diff --git a/drivers/gpu/drm/i915/selftests/mock_region.c b/drivers/gpu/drm/i915/selftests/mock_region.c
index f64325491f35..6f7c9820d3e9 100644
--- a/drivers/gpu/drm/i915/selftests/mock_region.c
+++ b/drivers/gpu/drm/i915/selftests/mock_region.c
@@ -32,7 +32,8 @@ 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;
--
2.35.1