linux/drivers/gpu/drm/i915/gt/selftest_engine_heartbeat.c

// SPDX-License-Identifier: MIT
/*
 * Copyright © 2018 Intel Corporation
 */

#include <linux/sort.h>

#include "i915_drv.h"

#include "intel_gt_requests.h"
#include "i915_selftest.h"
#include "selftest_engine_heartbeat.h"

static void reset_heartbeat(struct intel_engine_cs *engine)
{
	intel_engine_set_heartbeat(engine,
				   engine->defaults.heartbeat_interval_ms);
}

static int timeline_sync(struct intel_timeline *tl)
{
	struct dma_fence *fence;
	long timeout;

	fence = i915_active_fence_get(&tl->last_request);
	if (!fence)
		return 0;

	timeout = dma_fence_wait_timeout(fence, true, HZ / 2);
	dma_fence_put(fence);
	if (timeout < 0)
		return timeout;

	return 0;
}

static int engine_sync_barrier(struct intel_engine_cs *engine)
{
	return timeline_sync(engine->kernel_context->timeline);
}

struct pulse {
	struct i915_active active;
	struct kref kref;
};

static int pulse_active(struct i915_active *active)
{
	kref_get(&container_of(active, struct pulse, active)->kref);
	return 0;
}

static void pulse_free(struct kref *kref)
{
	struct pulse *p = container_of(kref, typeof(*p), kref);

	i915_active_fini(&p->active);
	kfree(p);
}

static void pulse_put(struct pulse *p)
{
	kref_put(&p->kref, pulse_free);
}

static void pulse_retire(struct i915_active *active)
{
	pulse_put(container_of(active, struct pulse, active));
}

static struct pulse *pulse_create(void)
{
	struct pulse *p;

	p = kmalloc(sizeof(*p), GFP_KERNEL);
	if (!p)
		return p;

	kref_init(&p->kref);
	i915_active_init(&p->active, pulse_active, pulse_retire, 0);

	return p;
}

static void pulse_unlock_wait(struct pulse *p)
{
	i915_active_unlock_wait(&p->active);
}

static int __live_idle_pulse(struct intel_engine_cs *engine,
			     int (*fn)(struct intel_engine_cs *cs))
{
	struct pulse *p;
	int err;

	GEM_BUG_ON(!intel_engine_pm_is_awake(engine));

	p = pulse_create();
	if (!p)
		return -ENOMEM;

	err = i915_active_acquire(&p->active);
	if (err)
		goto out;

	err = i915_active_acquire_preallocate_barrier(&p->active, engine);
	if (err) {
		i915_active_release(&p->active);
		goto out;
	}

	i915_active_acquire_barrier(&p->active);
	i915_active_release(&p->active);

	GEM_BUG_ON(i915_active_is_idle(&p->active));
	GEM_BUG_ON(llist_empty(&engine->barrier_tasks));

	err = fn(engine);
	if (err)
		goto out;

	GEM_BUG_ON(!llist_empty(&engine->barrier_tasks));

	if (engine_sync_barrier(engine)) {
		struct drm_printer m = drm_err_printer("pulse");

		pr_err("%s: no heartbeat pulse?\n", engine->name);
		intel_engine_dump(engine, &m, "%s", engine->name);

		err = -ETIME;
		goto out;
	}

	GEM_BUG_ON(READ_ONCE(engine->serial) != engine->wakeref_serial);

	pulse_unlock_wait(p); /* synchronize with the retirement callback */

	if (!i915_active_is_idle(&p->active)) {
		struct drm_printer m = drm_err_printer("pulse");

		pr_err("%s: heartbeat pulse did not flush idle tasks\n",
		       engine->name);
		i915_active_print(&p->active, &m);

		err = -EINVAL;
		goto out;
	}

out:
	pulse_put(p);
	return err;
}

static int live_idle_flush(void *arg)
{
	struct intel_gt *gt = arg;
	struct intel_engine_cs *engine;
	enum intel_engine_id id;
	int err = 0;

	/* Check that we can flush the idle barriers */

	for_each_engine(engine, gt, id) {
		st_engine_heartbeat_disable(engine);
		err = __live_idle_pulse(engine, intel_engine_flush_barriers);
		st_engine_heartbeat_enable(engine);
		if (err)
			break;
	}

	return err;
}

static int live_idle_pulse(void *arg)
{
	struct intel_gt *gt = arg;
	struct intel_engine_cs *engine;
	enum intel_engine_id id;
	int err = 0;

	/* Check that heartbeat pulses flush the idle barriers */

	for_each_engine(engine, gt, id) {
		st_engine_heartbeat_disable(engine);
		err = __live_idle_pulse(engine, intel_engine_pulse);
		st_engine_heartbeat_enable(engine);
		if (err && err != -ENODEV)
			break;

		err = 0;
	}

	return err;
}

static int cmp_u32(const void *_a, const void *_b)
{
	const u32 *a = _a, *b = _b;

	return *a - *b;
}

static int __live_heartbeat_fast(struct intel_engine_cs *engine)
{
	const unsigned int error_threshold = max(20000u, jiffies_to_usecs(6));
	struct intel_context *ce;
	struct i915_request *rq;
	ktime_t t0, t1;
	u32 times[5];
	int err;
	int i;

	ce = intel_context_create(engine);
	if (IS_ERR(ce))
		return PTR_ERR(ce);

	intel_engine_pm_get(engine);

	err = intel_engine_set_heartbeat(engine, 1);
	if (err)
		goto err_pm;

	for (i = 0; i < ARRAY_SIZE(times); i++) {
		do {
			/* Manufacture a tick */
			intel_engine_park_heartbeat(engine);
			GEM_BUG_ON(engine->heartbeat.systole);
			engine->serial++; /*  pretend we are not idle! */
			intel_engine_unpark_heartbeat(engine);

			flush_delayed_work(&engine->heartbeat.work);
			if (!delayed_work_pending(&engine->heartbeat.work)) {
				pr_err("%s: heartbeat %d did not start\n",
				       engine->name, i);
				err = -EINVAL;
				goto err_pm;
			}

			rcu_read_lock();
			rq = READ_ONCE(engine->heartbeat.systole);
			if (rq)
				rq = i915_request_get_rcu(rq);
			rcu_read_unlock();
		} while (!rq);

		t0 = ktime_get();
		while (rq == READ_ONCE(engine->heartbeat.systole))
			yield(); /* work is on the local cpu! */
		t1 = ktime_get();

		i915_request_put(rq);
		times[i] = ktime_us_delta(t1, t0);
	}

	sort(times, ARRAY_SIZE(times), sizeof(times[0]), cmp_u32, NULL);

	pr_info("%s: Heartbeat delay: %uus [%u, %u]\n",
		engine->name,
		times[ARRAY_SIZE(times) / 2],
		times[0],
		times[ARRAY_SIZE(times) - 1]);

	/*
	 * Ideally, the upper bound on min work delay would be something like
	 * 2 * 2 (worst), +1 for scheduling, +1 for slack. In practice, we
	 * are, even with system_wq_highpri, at the mercy of the CPU scheduler
	 * and may be stuck behind some slow work for many millisecond. Such
	 * as our very own display workers.
	 */
	if (times[ARRAY_SIZE(times) / 2] > error_threshold) {
		pr_err("%s: Heartbeat delay was %uus, expected less than %dus\n",
		       engine->name,
		       times[ARRAY_SIZE(times) / 2],
		       error_threshold);
		err = -EINVAL;
	}

	reset_heartbeat(engine);
err_pm:
	intel_engine_pm_put(engine);
	intel_context_put(ce);
	return err;
}

static int live_heartbeat_fast(void *arg)
{
	struct intel_gt *gt = arg;
	struct intel_engine_cs *engine;
	enum intel_engine_id id;
	int err = 0;

	/* Check that the heartbeat ticks at the desired rate. */
	if (!IS_ACTIVE(CONFIG_DRM_I915_HEARTBEAT_INTERVAL))
		return 0;

	for_each_engine(engine, gt, id) {
		err = __live_heartbeat_fast(engine);
		if (err)
			break;
	}

	return err;
}

static int __live_heartbeat_off(struct intel_engine_cs *engine)
{
	int err;

	intel_engine_pm_get(engine);

	engine->serial++;
	flush_delayed_work(&engine->heartbeat.work);
	if (!delayed_work_pending(&engine->heartbeat.work)) {
		pr_err("%s: heartbeat not running\n",
		       engine->name);
		err = -EINVAL;
		goto err_pm;
	}

	err = intel_engine_set_heartbeat(engine, 0);
	if (err)
		goto err_pm;

	engine->serial++;
	flush_delayed_work(&engine->heartbeat.work);
	if (delayed_work_pending(&engine->heartbeat.work)) {
		pr_err("%s: heartbeat still running\n",
		       engine->name);
		err = -EINVAL;
		goto err_beat;
	}

	if (READ_ONCE(engine->heartbeat.systole)) {
		pr_err("%s: heartbeat still allocated\n",
		       engine->name);
		err = -EINVAL;
		goto err_beat;
	}

err_beat:
	reset_heartbeat(engine);
err_pm:
	intel_engine_pm_put(engine);
	return err;
}

static int live_heartbeat_off(void *arg)
{
	struct intel_gt *gt = arg;
	struct intel_engine_cs *engine;
	enum intel_engine_id id;
	int err = 0;

	/* Check that we can turn off heartbeat and not interrupt VIP */
	if (!IS_ACTIVE(CONFIG_DRM_I915_HEARTBEAT_INTERVAL))
		return 0;

	for_each_engine(engine, gt, id) {
		if (!intel_engine_has_preemption(engine))
			continue;

		err = __live_heartbeat_off(engine);
		if (err)
			break;
	}

	return err;
}

int intel_heartbeat_live_selftests(struct drm_i915_private *i915)
{
	static const struct i915_subtest tests[] = {
		SUBTEST(live_idle_flush),
		SUBTEST(live_idle_pulse),
		SUBTEST(live_heartbeat_fast),
		SUBTEST(live_heartbeat_off),
	};
	int saved_hangcheck;
	int err;

	if (intel_gt_is_wedged(&i915->gt))
		return 0;

	saved_hangcheck = i915->params.enable_hangcheck;
	i915->params.enable_hangcheck = INT_MAX;

	err = intel_gt_live_subtests(tests, &i915->gt);

	i915->params.enable_hangcheck = saved_hangcheck;
	return err;
}

void st_engine_heartbeat_disable(struct intel_engine_cs *engine)
{
	engine->props.heartbeat_interval_ms = 0;

	intel_engine_pm_get(engine);
	intel_engine_park_heartbeat(engine);
}

void st_engine_heartbeat_enable(struct intel_engine_cs *engine)
{
	intel_engine_pm_put(engine);

	engine->props.heartbeat_interval_ms =
		engine->defaults.heartbeat_interval_ms;
}