drm/i915/selftests: Add a cancel request selftest that triggers a reset

Add a cancel request selftest that results in an engine reset to cancel
the request as it is non-preemptable. Also insert a NOP request after
the cancelled request and confirm that it completes successfully.

v2:
 (Tvrtko)
  - Skip test if preemption timeout compiled out
  - Skip test if engine reset isn't supported
  - Update debug prints to be more descriptive
v3:
  - Add comment explaining test
v4:
 (John Harrison)
  - Fix typos in comment explaining test
  - goto out_rq is NOP creation fails
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220113181351.21296-2-matthew.brost@intel.com

drivers/gpu/drm/i915/selftests/i915_request.c

@@ -782,6 +782,115 @@ static int __cancel_completed(struct intel_engine_cs *engine)
 	return err;
 }
 
+/*
+ * Test to prove a non-preemptable request can be cancelled and a subsequent
+ * request on the same context can successfully complete after cancellation.
+ *
+ * Testing methodology is to create a non-preemptible request and submit it,
+ * wait for spinner to start, create a NOP request and submit it, cancel the
+ * spinner, wait for spinner to complete and verify it failed with an error,
+ * finally wait for NOP request to complete verify it succeeded without an
+ * error. Preemption timeout also reduced / restored so test runs in a timely
+ * maner.
+ */
+static int __cancel_reset(struct drm_i915_private *i915,
+			  struct intel_engine_cs *engine)
+{
+	struct intel_context *ce;
+	struct igt_spinner spin;
+	struct i915_request *rq, *nop;
+	unsigned long preempt_timeout_ms;
+	int err = 0;
+
+	if (!CONFIG_DRM_I915_PREEMPT_TIMEOUT ||
+	    !intel_has_reset_engine(engine->gt))
+		return 0;
+
+	preempt_timeout_ms = engine->props.preempt_timeout_ms;
+	engine->props.preempt_timeout_ms = 100;
+
+	if (igt_spinner_init(&spin, engine->gt))
+		goto out_restore;
+
+	ce = intel_context_create(engine);
+	if (IS_ERR(ce)) {
+		err = PTR_ERR(ce);
+		goto out_spin;
+	}
+
+	rq = igt_spinner_create_request(&spin, ce, MI_NOOP);
+	if (IS_ERR(rq)) {
+		err = PTR_ERR(rq);
+		goto out_ce;
+	}
+
+	pr_debug("%s: Cancelling active non-preemptable request\n",
+		 engine->name);
+	i915_request_get(rq);
+	i915_request_add(rq);
+	if (!igt_wait_for_spinner(&spin, rq)) {
+		struct drm_printer p = drm_info_printer(engine->i915->drm.dev);
+
+		pr_err("Failed to start spinner on %s\n", engine->name);
+		intel_engine_dump(engine, &p, "%s\n", engine->name);
+		err = -ETIME;
+		goto out_rq;
+	}
+
+	nop = intel_context_create_request(ce);
+	if (IS_ERR(nop))
+		goto out_rq;
+	i915_request_get(nop);
+	i915_request_add(nop);
+
+	i915_request_cancel(rq, -EINTR);
+
+	if (i915_request_wait(rq, 0, HZ) < 0) {
+		struct drm_printer p = drm_info_printer(engine->i915->drm.dev);
+
+		pr_err("%s: Failed to cancel hung request\n", engine->name);
+		intel_engine_dump(engine, &p, "%s\n", engine->name);
+		err = -ETIME;
+		goto out_nop;
+	}
+
+	if (rq->fence.error != -EINTR) {
+		pr_err("%s: fence not cancelled (%u)\n",
+		       engine->name, rq->fence.error);
+		err = -EINVAL;
+		goto out_nop;
+	}
+
+	if (i915_request_wait(nop, 0, HZ) < 0) {
+		struct drm_printer p = drm_info_printer(engine->i915->drm.dev);
+
+		pr_err("%s: Failed to complete nop request\n", engine->name);
+		intel_engine_dump(engine, &p, "%s\n", engine->name);
+		err = -ETIME;
+		goto out_nop;
+	}
+
+	if (nop->fence.error != 0) {
+		pr_err("%s: Nop request errored (%u)\n",
+		       engine->name, nop->fence.error);
+		err = -EINVAL;
+	}
+
+out_nop:
+	i915_request_put(nop);
+out_rq:
+	i915_request_put(rq);
+out_ce:
+	intel_context_put(ce);
+out_spin:
+	igt_spinner_fini(&spin);
+out_restore:
+	engine->props.preempt_timeout_ms = preempt_timeout_ms;
+	if (err)
+		pr_err("%s: %s error %d\n", __func__, engine->name, err);
+	return err;
+}
+
 static int live_cancel_request(void *arg)
 {
 	struct drm_i915_private *i915 = arg;
@@ -814,6 +923,14 @@ static int live_cancel_request(void *arg)
 			return err;
 		if (err2)
 			return err2;
+
+		/* Expects reset so call outside of igt_live_test_* */
+		err = __cancel_reset(i915, engine);
+		if (err)
+			return err;
+
+		if (igt_flush_test(i915))
+			return -EIO;
 	}
 
 	return 0;