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.
Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>
---
.../gpu/drm/i915/gt/uc/intel_guc_submission.c | 32 +++++++++++++++----
1 file changed, 26 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
index 3ae92260f8224..d562d85f96871 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -4493,27 +4493,31 @@ 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,
@@ -4523,6 +4527,12 @@ 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;
@@ -4565,22 +4575,25 @@ 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,
@@ -4590,10 +4603,17 @@ 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,
--
2.34.1
