| Message ID | 20180822132714.1240-1-mika.kuoppala@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/i915/gtt: Setup guards in scratch page | expand |
Quoting Mika Kuoppala (2018-08-22 14:27:14) > 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. You are trading an obvious error for a subtle one; if userspace got its batch wrong and doesn't die, the output will likely be wrong instead. mesa/src/intel/tools/intel_sanitize_gpu for how userspace could do this detection itself. You can intercept the execbuf, place a canary after the batch and report if the canary gets written. -Chris
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:
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@chris-wilson.co.uk> Cc: Matthew Auld <matthew.auld@intel.com> Signed-off-by: Mika Kuoppala <mika.kuoppala@linux.intel.com> --- drivers/gpu/drm/i915/i915_gem_gtt.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+)