[Intel-gfx] [PATCH 1/4] drm/i915/gt: GEM_BUG_ON unexpected NULL at scatterlist walking

[Ramalingam C <ramalingam.c@intel.com>]

While locating the start of ccs scatterlist in smem scatterlist, that has
to be the size of lmem obj size + corresponding ccs data size. Report bug
if scatterlist terminate before that length.

Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
---
 drivers/gpu/drm/i915/gt/intel_migrate.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/i915/gt/intel_migrate.c b/drivers/gpu/drm/i915/gt/intel_migrate.c
index 9d552f30b627..29d761da02c4 100644
--- a/drivers/gpu/drm/i915/gt/intel_migrate.c
+++ b/drivers/gpu/drm/i915/gt/intel_migrate.c
@@ -687,6 +687,12 @@ static void get_ccs_sg_sgt(struct sgt_dma *it, u32 bytes_to_cpy)
 		bytes_to_cpy -= len;
 
 		it->sg = __sg_next(it->sg);
+
+		/*
+		 * scatterlist supposed to be the size of
+		 * bytes_to_cpy + GET_CCS_BYTES(bytes_to_copy).
+		 */
+		GEM_BUG_ON(!it->sg);
 		it->dma = sg_dma_address(it->sg);
 		it->max = it->dma + sg_dma_len(it->sg);
 	} while (bytes_to_cpy);
-- 
2.20.1