Commit 85e97b1d authored by Matthew Brost's avatar Matthew Brost Committed by John Harrison
Browse files

drm/i915/guc: Ensure multi-lrc fini breadcrumb math is correct 



Realized that the GuC multi-lrc fini breadcrumb emit code is very
delicate as the math this code does relies on functions it calls to emit
a certain number of DWs. Add a few GEM_BUG_ONs to assert the math is
correct.

v2:
  - Rebase + resend for CI
 (Checkpatch)
  - Fix blank line warning

Signed-off-by: default avatarMatthew Brost <matthew.brost@intel.com>
Reviewed-by: default avatarJohn Harrison <John.C.Harrison@Intel.com>
Signed-off-by: default avatarJohn Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220119210639.33053-1-matthew.brost@intel.com
parent ff3aeb34

drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c

+27 −6
Original line number Diff line number Diff line
@@ -4441,27 +4441,31 @@ static inline bool skip_handshake(struct i915_request *rq) 
	return test_bit(I915_FENCE_FLAG_SKIP_PARALLEL, &rq->fence.flags);

}



#define NON_SKIP_LEN	6

static u32 *

emit_fini_breadcrumb_parent_no_preempt_mid_batch(struct i915_request *rq,

						 u32 *cs)

{

	struct intel_context *ce = rq->context;

	__maybe_unused u32 *before_fini_breadcrumb_user_interrupt_cs;

	__maybe_unused u32 *start_fini_breadcrumb_cs = cs;



	GEM_BUG_ON(!intel_context_is_parent(ce));



	if (unlikely(skip_handshake(rq))) {

		/*

		 * NOP everything in __emit_fini_breadcrumb_parent_no_preempt_mid_batch,

		 * the -6 comes from the length of the emits below.

		 * the NON_SKIP_LEN comes from the length of the emits below.

		 */

		memset(cs, 0, sizeof(u32) *

		       (ce->engine->emit_fini_breadcrumb_dw - 6));

		cs += ce->engine->emit_fini_breadcrumb_dw - 6;

		       (ce->engine->emit_fini_breadcrumb_dw - NON_SKIP_LEN));

		cs += ce->engine->emit_fini_breadcrumb_dw - NON_SKIP_LEN;

	} else {

		cs = __emit_fini_breadcrumb_parent_no_preempt_mid_batch(rq, cs);

	}



	/* Emit fini breadcrumb */

	before_fini_breadcrumb_user_interrupt_cs = cs;

	cs = gen8_emit_ggtt_write(cs,

				  rq->fence.seqno,

				  i915_request_active_timeline(rq)->hwsp_offset,
@@ -4471,6 +4475,12 @@ emit_fini_breadcrumb_parent_no_preempt_mid_batch(struct i915_request *rq, 
	*cs++ = MI_USER_INTERRUPT;

	*cs++ = MI_NOOP;



	/* Ensure our math for skip + emit is correct */

	GEM_BUG_ON(before_fini_breadcrumb_user_interrupt_cs + NON_SKIP_LEN !=

		   cs);

	GEM_BUG_ON(start_fini_breadcrumb_cs +

		   ce->engine->emit_fini_breadcrumb_dw != cs);



	rq->tail = intel_ring_offset(rq, cs);



	return cs;
@@ -4513,22 +4523,25 @@ emit_fini_breadcrumb_child_no_preempt_mid_batch(struct i915_request *rq, 
						u32 *cs)

{

	struct intel_context *ce = rq->context;

	__maybe_unused u32 *before_fini_breadcrumb_user_interrupt_cs;

	__maybe_unused u32 *start_fini_breadcrumb_cs = cs;



	GEM_BUG_ON(!intel_context_is_child(ce));



	if (unlikely(skip_handshake(rq))) {

		/*

		 * NOP everything in __emit_fini_breadcrumb_child_no_preempt_mid_batch,

		 * the -6 comes from the length of the emits below.

		 * the NON_SKIP_LEN comes from the length of the emits below.

		 */

		memset(cs, 0, sizeof(u32) *

		       (ce->engine->emit_fini_breadcrumb_dw - 6));

		cs += ce->engine->emit_fini_breadcrumb_dw - 6;

		       (ce->engine->emit_fini_breadcrumb_dw - NON_SKIP_LEN));

		cs += ce->engine->emit_fini_breadcrumb_dw - NON_SKIP_LEN;

	} else {

		cs = __emit_fini_breadcrumb_child_no_preempt_mid_batch(rq, cs);

	}



	/* Emit fini breadcrumb */

	before_fini_breadcrumb_user_interrupt_cs = cs;

	cs = gen8_emit_ggtt_write(cs,

				  rq->fence.seqno,

				  i915_request_active_timeline(rq)->hwsp_offset,
@@ -4538,11 +4551,19 @@ emit_fini_breadcrumb_child_no_preempt_mid_batch(struct i915_request *rq, 
	*cs++ = MI_USER_INTERRUPT;

	*cs++ = MI_NOOP;



	/* Ensure our math for skip + emit is correct */

	GEM_BUG_ON(before_fini_breadcrumb_user_interrupt_cs + NON_SKIP_LEN !=

		   cs);

	GEM_BUG_ON(start_fini_breadcrumb_cs +

		   ce->engine->emit_fini_breadcrumb_dw != cs);



	rq->tail = intel_ring_offset(rq, cs);



	return cs;

}



#undef NON_SKIP_LEN



static struct intel_context *

guc_create_virtual(struct intel_engine_cs **siblings, unsigned int count,

		   unsigned long flags)