drm/i915/selftests: Add tests for timeslicing virtual engines

Make sure that we can execute a virtual request on an already busy
engine, and conversely that we can execute a normal request if the
engines are already fully occupied by virtual requests.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200519132046.22443-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/gt/selftest_lrc.c

@@ -3591,9 +3591,11 @@ static int nop_virtual_engine(struct intel_gt *gt,
 	return err;
 }
 
-static unsigned int select_siblings(struct intel_gt *gt,
+static unsigned int
+__select_siblings(struct intel_gt *gt,
 		  unsigned int class,
-				    struct intel_engine_cs **siblings)
+		  struct intel_engine_cs **siblings,
+		  bool (*filter)(const struct intel_engine_cs *))
 {
 	unsigned int n = 0;
 	unsigned int inst;
@@ -3602,12 +3604,23 @@ static unsigned int select_siblings(struct intel_gt *gt,
 		if (!gt->engine_class[class][inst])
 			continue;
 
+		if (filter && !filter(gt->engine_class[class][inst]))
+			continue;
+
 		siblings[n++] = gt->engine_class[class][inst];
 	}
 
 	return n;
 }
 
+static unsigned int
+select_siblings(struct intel_gt *gt,
+		unsigned int class,
+		struct intel_engine_cs **siblings)
+{
+	return __select_siblings(gt, class, siblings, NULL);
+}
+
 static int live_virtual_engine(void *arg)
 {
 	struct intel_gt *gt = arg;
@@ -3762,6 +3775,186 @@ static int live_virtual_mask(void *arg)
 	return 0;
 }
 
+static long slice_timeout(struct intel_engine_cs *engine)
+{
+	long timeout;
+
+	/* Enough time for a timeslice to kick in, and kick out */
+	timeout = 2 * msecs_to_jiffies_timeout(timeslice(engine));
+
+	/* Enough time for the nop request to complete */
+	timeout += HZ / 5;
+
+	return timeout;
+}
+
+static int slicein_virtual_engine(struct intel_gt *gt,
+				  struct intel_engine_cs **siblings,
+				  unsigned int nsibling)
+{
+	const long timeout = slice_timeout(siblings[0]);
+	struct intel_context *ce;
+	struct i915_request *rq;
+	struct igt_spinner spin;
+	unsigned int n;
+	int err = 0;
+
+	/*
+	 * Virtual requests must take part in timeslicing on the target engines.
+	 */
+
+	if (igt_spinner_init(&spin, gt))
+		return -ENOMEM;
+
+	for (n = 0; n < nsibling; n++) {
+		ce = intel_context_create(siblings[n]);
+		if (IS_ERR(ce)) {
+			err = PTR_ERR(ce);
+			goto out;
+		}
+
+		rq = igt_spinner_create_request(&spin, ce, MI_ARB_CHECK);
+		intel_context_put(ce);
+		if (IS_ERR(rq)) {
+			err = PTR_ERR(rq);
+			goto out;
+		}
+
+		i915_request_add(rq);
+	}
+
+	ce = intel_execlists_create_virtual(siblings, nsibling);
+	if (IS_ERR(ce)) {
+		err = PTR_ERR(ce);
+		goto out;
+	}
+
+	rq = intel_context_create_request(ce);
+	intel_context_put(ce);
+	if (IS_ERR(rq)) {
+		err = PTR_ERR(rq);
+		goto out;
+	}
+
+	i915_request_get(rq);
+	i915_request_add(rq);
+	if (i915_request_wait(rq, 0, timeout) < 0) {
+		GEM_TRACE_ERR("%s(%s) failed to slice in virtual request\n",
+			      __func__, rq->engine->name);
+		GEM_TRACE_DUMP();
+		intel_gt_set_wedged(gt);
+		err = -EIO;
+	}
+	i915_request_put(rq);
+
+out:
+	igt_spinner_end(&spin);
+	if (igt_flush_test(gt->i915))
+		err = -EIO;
+	igt_spinner_fini(&spin);
+	return err;
+}
+
+static int sliceout_virtual_engine(struct intel_gt *gt,
+				   struct intel_engine_cs **siblings,
+				   unsigned int nsibling)
+{
+	const long timeout = slice_timeout(siblings[0]);
+	struct intel_context *ce;
+	struct i915_request *rq;
+	struct igt_spinner spin;
+	unsigned int n;
+	int err = 0;
+
+	/*
+	 * Virtual requests must allow others a fair timeslice.
+	 */
+
+	if (igt_spinner_init(&spin, gt))
+		return -ENOMEM;
+
+	/* XXX We do not handle oversubscription and fairness with normal rq */
+	for (n = 0; n < nsibling; n++) {
+		ce = intel_execlists_create_virtual(siblings, nsibling);
+		if (IS_ERR(ce)) {
+			err = PTR_ERR(ce);
+			goto out;
+		}
+
+		rq = igt_spinner_create_request(&spin, ce, MI_ARB_CHECK);
+		intel_context_put(ce);
+		if (IS_ERR(rq)) {
+			err = PTR_ERR(rq);
+			goto out;
+		}
+
+		i915_request_add(rq);
+	}
+
+	for (n = 0; !err && n < nsibling; n++) {
+		ce = intel_context_create(siblings[n]);
+		if (IS_ERR(ce)) {
+			err = PTR_ERR(ce);
+			goto out;
+		}
+
+		rq = intel_context_create_request(ce);
+		intel_context_put(ce);
+		if (IS_ERR(rq)) {
+			err = PTR_ERR(rq);
+			goto out;
+		}
+
+		i915_request_get(rq);
+		i915_request_add(rq);
+		if (i915_request_wait(rq, 0, timeout) < 0) {
+			GEM_TRACE_ERR("%s(%s) failed to slice out virtual request\n",
+				      __func__, siblings[n]->name);
+			GEM_TRACE_DUMP();
+			intel_gt_set_wedged(gt);
+			err = -EIO;
+		}
+		i915_request_put(rq);
+	}
+
+out:
+	igt_spinner_end(&spin);
+	if (igt_flush_test(gt->i915))
+		err = -EIO;
+	igt_spinner_fini(&spin);
+	return err;
+}
+
+static int live_virtual_slice(void *arg)
+{
+	struct intel_gt *gt = arg;
+	struct intel_engine_cs *siblings[MAX_ENGINE_INSTANCE + 1];
+	unsigned int class;
+	int err;
+
+	if (intel_uc_uses_guc_submission(&gt->uc))
+		return 0;
+
+	for (class = 0; class <= MAX_ENGINE_CLASS; class++) {
+		unsigned int nsibling;
+
+		nsibling = __select_siblings(gt, class, siblings,
+					     intel_engine_has_timeslices);
+		if (nsibling < 2)
+			continue;
+
+		err = slicein_virtual_engine(gt, siblings, nsibling);
+		if (err)
+			return err;
+
+		err = sliceout_virtual_engine(gt, siblings, nsibling);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
 static int preserved_virtual_engine(struct intel_gt *gt,
 				    struct intel_engine_cs **siblings,
 				    unsigned int nsibling)
@@ -4297,6 +4490,7 @@ int intel_execlists_live_selftests(struct drm_i915_private *i915)
 		SUBTEST(live_virtual_engine),
 		SUBTEST(live_virtual_mask),
 		SUBTEST(live_virtual_preserved),
+		SUBTEST(live_virtual_slice),
 		SUBTEST(live_virtual_bond),
 		SUBTEST(live_virtual_reset),
 	};