Commit 8676145e authored by Matthew Auld's avatar Matthew Auld
Browse files

drm/i915/ttm: fix CCS handling 



Crucible + recent Mesa seems to sometimes hit:

GEM_BUG_ON(num_ccs_blks > NUM_CCS_BLKS_PER_XFER)

And it looks like we can also trigger this with gem_lmem_swapping, if we
modify the test to use slightly larger object sizes.

Looking closer it looks like we have the following issues in
migrate_copy():

  - We are using plain integer in various places, which we can easily
    overflow with a large object.

  - We pass the entire object size (when the src is lmem) into
    emit_pte() and then try to copy it, which doesn't work, since we
    only have a few fixed sized windows in which to map the pages and
    perform the copy. With an object > 8M we therefore aren't properly
    copying the pages. And then with an object > 64M we trigger the
    GEM_BUG_ON(num_ccs_blks > NUM_CCS_BLKS_PER_XFER).

So it looks like our copy handling for any object > 8M (which is our
CHUNK_SZ) is currently broken on DG2.

Fixes: da0595ae ("drm/i915/migrate: Evict and restore the flatccs capable lmem obj")
Testcase: igt@gem_lmem_swapping
Signed-off-by: default avatarMatthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Ramalingam C <ramalingam.c@intel.com>
Reviewed-by: default avatarRamalingam <C&lt;ramalingam.c@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220805132240.442747-2-matthew.auld@intel.com
parent dba4d442

drivers/gpu/drm/i915/gt/intel_migrate.c

+21 −23
Original line number Diff line number Diff line
@@ -609,9 +609,9 @@ static int emit_copy(struct i915_request *rq, 
	return 0;

}



static int scatter_list_length(struct scatterlist *sg)

static u64 scatter_list_length(struct scatterlist *sg)

{

	int len = 0;

	u64 len = 0;



	while (sg && sg_dma_len(sg)) {

		len += sg_dma_len(sg);
@@ -621,12 +621,11 @@ static int scatter_list_length(struct scatterlist *sg) 
	return len;

}



static void

static int

calculate_chunk_sz(struct drm_i915_private *i915, bool src_is_lmem,

		   int *src_sz, u32 bytes_to_cpy, u32 ccs_bytes_to_cpy)

		   u64 bytes_to_cpy, u64 ccs_bytes_to_cpy)

{

	if (ccs_bytes_to_cpy) {

		if (!src_is_lmem)

	if (ccs_bytes_to_cpy && !src_is_lmem)

		/*

		 * When CHUNK_SZ is passed all the pages upto CHUNK_SZ

		 * will be taken for the blt. in Flat-ccs supported
@@ -634,15 +633,14 @@ calculate_chunk_sz(struct drm_i915_private *i915, bool src_is_lmem, 
		 * for main meory hence limit it to the required size

		 * for main memory

		 */

			*src_sz = min_t(int, bytes_to_cpy, CHUNK_SZ);

	} else { /* ccs handling is not required */

		*src_sz = CHUNK_SZ;

	}

		return min_t(u64, bytes_to_cpy, CHUNK_SZ);

	else

		return CHUNK_SZ;

}



static void get_ccs_sg_sgt(struct sgt_dma *it, u32 bytes_to_cpy)

static void get_ccs_sg_sgt(struct sgt_dma *it, u64 bytes_to_cpy)

{

	u32 len;

	u64 len;



	do {

		GEM_BUG_ON(!it->sg || !sg_dma_len(it->sg));
@@ -673,12 +671,12 @@ intel_context_migrate_copy(struct intel_context *ce, 
{

	struct sgt_dma it_src = sg_sgt(src), it_dst = sg_sgt(dst), it_ccs;

	struct drm_i915_private *i915 = ce->engine->i915;

	u32 ccs_bytes_to_cpy = 0, bytes_to_cpy;

	u64 ccs_bytes_to_cpy = 0, bytes_to_cpy;

	enum i915_cache_level ccs_cache_level;

	u32 src_offset, dst_offset;

	u8 src_access, dst_access;

	struct i915_request *rq;

	int src_sz, dst_sz;

	u64 src_sz, dst_sz;

	bool ccs_is_src, overwrite_ccs;

	int err;
@@ -761,7 +759,7 @@ intel_context_migrate_copy(struct intel_context *ce, 
		if (err)

			goto out_rq;



		calculate_chunk_sz(i915, src_is_lmem, &src_sz,

		src_sz = calculate_chunk_sz(i915, src_is_lmem,

					    bytes_to_cpy, ccs_bytes_to_cpy);



		len = emit_pte(rq, &it_src, src_cache_level, src_is_lmem,