From 826259f5e5260df5349907e60f8ad31b2ec7a485 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Fri, 6 Mar 2020 07:16:12 +0000
Subject: drm/i915: Assert requests within a context are submitted in order
Git-commit: 1eaa251b66a6dfb53cc647fbd79e3b8512ccf8f3
Patch-mainline: v5.7-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322

Check the flow of requests into the hardware to verify that are
submitted in order along their timeline.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200306071614.2846708-1-chris@chris-wilson.co.uk
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/i915/gt/intel_lrc.c |  4 ++++
 drivers/gpu/drm/i915/i915_request.c | 11 +++++++++++
 2 files changed, 15 insertions(+)

diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 07d137851763..1d63aef8e973 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -1622,6 +1622,7 @@ static bool can_merge_rq(const struct i915_request *prev,
 	if (!can_merge_ctx(prev->context, next->context))
 		return false;
 
+	GEM_BUG_ON(i915_seqno_passed(prev->fence.seqno, next->fence.seqno));
 	return true;
 }
 
@@ -2141,6 +2142,9 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
 				GEM_BUG_ON(last &&
 					   !can_merge_ctx(last->context,
 							  rq->context));
+				GEM_BUG_ON(last &&
+					   i915_seqno_passed(last->fence.seqno,
+							     rq->fence.seqno));
 
 				submit = true;
 				last = rq;
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 92a4331df5fd..da88f9082b5a 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -749,6 +749,7 @@ __i915_request_create(struct intel_context *ce, gfp_t gfp)
 	RCU_INIT_POINTER(rq->timeline, tl);
 	RCU_INIT_POINTER(rq->hwsp_cacheline, tl->hwsp_cacheline);
 	rq->hwsp_seqno = tl->hwsp_seqno;
+	GEM_BUG_ON(i915_request_completed(rq));
 
 	rq->rcustate = get_state_synchronize_rcu(); /* acts as smp_mb() */
 
@@ -1296,6 +1297,16 @@ __i915_request_add_to_timeline(struct i915_request *rq)
 	prev = to_request(__i915_active_fence_set(&timeline->last_request,
 						  &rq->fence));
 	if (prev && !i915_request_completed(prev)) {
+		/*
+		 * The requests are supposed to be kept in order. However,
+		 * we need to be wary in case the timeline->last_request
+		 * is used as a barrier for external modification to this
+		 * context.
+		 */
+		GEM_BUG_ON(prev->context == rq->context &&
+			   i915_seqno_passed(prev->fence.seqno,
+					     rq->fence.seqno));
+
 		if (is_power_of_2(prev->engine->mask | rq->engine->mask))
 			i915_sw_fence_await_sw_fence(&rq->submit,
 						     &prev->submit,
-- 
2.28.0