There have been cases where GPU engine has managed to run past
execbuffer ending due to reasons unknown at that time:
coherency problems, page table setup errors, hw glitches.
Let's try to contain a wild engine head by putting batch
buffer end commands into start and end of scratch page.
v2: add more signature
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Matthew Auld <matthew.auld@xxxxxxxxx>
Signed-off-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_gem_gtt.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 4137af4bd8f5..3c617874ee7c 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -617,6 +617,24 @@ static void fill_page_dma_32(struct i915_address_space *vm,
fill_page_dma(vm, p, (u64)v << 32 | v);
}
+static void setup_scratch_page_guards(struct i915_address_space *vm)
+{
+ struct i915_page_dma const *p = &vm->scratch_page;
+ u32 *scratch;
+ const unsigned int size = BIT(p->order) << PAGE_SHIFT;
+ const unsigned int last_idx = size / sizeof(*scratch) - 1;
+
+ scratch = kmap_atomic(p->page);
+
+ scratch[0] = MI_BATCH_BUFFER_END;
+ scratch[1] = MI_BATCH_BUFFER_END;
+
+ scratch[last_idx - 1] = MI_BATCH_BUFFER_END;
+ scratch[last_idx] = MI_BATCH_BUFFER_END;
+
+ kunmap_atomic(scratch);
+}
+
static int
setup_scratch_page(struct i915_address_space *vm, gfp_t gfp)
{
@@ -665,6 +683,9 @@ setup_scratch_page(struct i915_address_space *vm, gfp_t gfp)
vm->scratch_page.page = page;
vm->scratch_page.daddr = addr;
vm->scratch_page.order = order;
+
+ setup_scratch_page_guards(vm);
+
return 0;
unmap_page:
--
2.17.1
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