diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 34f67eb9bfa1..d42a9d6767d4 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -3649,7 +3649,26 @@ static void reset_csb_pointers(struct intel_engine_cs *engine)
 
 static void execlists_sanitize(struct intel_engine_cs *engine)
 {
+	/*
+	 * Poison residual state on resume, in case the suspend didn't!
+	 *
+	 * We have to assume that across suspend/resume (or other loss
+	 * of control) that the contents of our pinned buffers has been
+	 * lost, replaced by garbage. Since this doesn't always happen,
+	 * let's poison such state so that we more quickly spot when
+	 * we falsely assume it has been preserved.
+	 */
+	if (IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM))
+		memset(engine->status_page.addr, POISON_INUSE, PAGE_SIZE);
+
 	reset_csb_pointers(engine);
+
+	/*
+	 * The kernel_context HWSP is stored in the status_page. As above,
+	 * that may be lost on resume/initialisation, and so we need to
+	 * reset the value in the HWSP.
+	 */
+	intel_timeline_reset_seqno(engine->kernel_context->timeline);
 }
 
 static void enable_error_interrupt(struct intel_engine_cs *engine)
@@ -4539,6 +4558,8 @@ static void execlists_shutdown(struct intel_engine_cs *engine)
 
 static void execlists_release(struct intel_engine_cs *engine)
 {
+	engine->sanitize = NULL; /* no longer in control, nothing to sanitize */
+
 	execlists_shutdown(engine);
 
 	intel_engine_cleanup_common(engine);
@@ -4550,7 +4571,6 @@ logical_ring_default_vfuncs(struct intel_engine_cs *engine)
 {
 	/* Default vfuncs which can be overriden by each engine. */
 
-	engine->sanitize = execlists_sanitize;
 	engine->resume = execlists_resume;
 
 	engine->cops = &execlists_context_ops;
@@ -4666,6 +4686,7 @@ int intel_execlists_submission_setup(struct intel_engine_cs *engine)
 		execlists->csb_size = GEN11_CSB_ENTRIES;
 
 	/* Finally, take ownership and responsibility for cleanup! */
+	engine->sanitize = execlists_sanitize;
 	engine->release = execlists_release;
 
 	return 0;
diff --git a/drivers/gpu/drm/i915/gt/intel_timeline.c b/drivers/gpu/drm/i915/gt/intel_timeline.c
index 3779c2ae0d65..29a39e44fa36 100644
--- a/drivers/gpu/drm/i915/gt/intel_timeline.c
+++ b/drivers/gpu/drm/i915/gt/intel_timeline.c
@@ -337,6 +337,13 @@ int intel_timeline_pin(struct intel_timeline *tl)
 	return 0;
 }
 
+void intel_timeline_reset_seqno(const struct intel_timeline *tl)
+{
+	/* Must be pinned to be writable, and no requests in flight. */
+	GEM_BUG_ON(!atomic_read(&tl->pin_count));
+	WRITE_ONCE(*(u32 *)tl->hwsp_seqno, tl->seqno);
+}
+
 void intel_timeline_enter(struct intel_timeline *tl)
 {
 	struct intel_gt_timelines *timelines = &tl->gt->timelines;
@@ -365,8 +372,16 @@ void intel_timeline_enter(struct intel_timeline *tl)
 		return;
 
 	spin_lock(&timelines->lock);
-	if (!atomic_fetch_inc(&tl->active_count))
+	if (!atomic_fetch_inc(&tl->active_count)) {
+		/*
+		 * The HWSP is volatile, and may have been lost while inactive,
+		 * e.g. across suspend/resume. Be paranoid, and ensure that
+		 * the HWSP value matches our seqno so we don't proclaim
+		 * the next request as already complete.
+		 */
+		intel_timeline_reset_seqno(tl);
 		list_add_tail(&tl->link, &timelines->active_list);
+	}
 	spin_unlock(&timelines->lock);
 }
 
diff --git a/drivers/gpu/drm/i915/gt/intel_timeline.h b/drivers/gpu/drm/i915/gt/intel_timeline.h
index f5b7eade3809..c8e59a333182 100644
--- a/drivers/gpu/drm/i915/gt/intel_timeline.h
+++ b/drivers/gpu/drm/i915/gt/intel_timeline.h
@@ -84,6 +84,8 @@ int intel_timeline_get_seqno(struct intel_timeline *tl,
 void intel_timeline_exit(struct intel_timeline *tl);
 void intel_timeline_unpin(struct intel_timeline *tl);
 
+void intel_timeline_reset_seqno(const struct intel_timeline *tl);
+
 int intel_timeline_read_hwsp(struct i915_request *from,
 			     struct i915_request *until,
 			     u32 *hwsp_offset);