clear-pkgs-linux-iot-lts2018/0791-drm-i915-Allow-user-control-over-preempt-timeout-on-.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Mon, 10 Dec 2018 04:34:57 -0500
Subject: [PATCH] drm/i915: Allow user control over preempt timeout on their
 important context

One usecase would be to couple in via EGL_NV_context_priority_realtime
in userspace to provide some QoS guarantees in conjunction with setting
the highest priority.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

backporting from: https://patchwork.freedesktop.org/series/43299/
Tracked-On: OLINUX-5626

Signed-off-by: kimsehun <se.hun.kim@intel.com>
---
 drivers/gpu/drm/i915/i915_gem_context.c    | 22 ++++++
 drivers/gpu/drm/i915/i915_gem_context.h    | 13 ++++
 drivers/gpu/drm/i915/i915_request.c        |  7 +-
 drivers/gpu/drm/i915/intel_lrc.c           | 10 +--
 drivers/gpu/drm/i915/selftests/intel_lrc.c | 85 ++++++++++++++++++++++
 include/uapi/drm/i915_drm.h                | 12 +++
 6 files changed, 142 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index f1ab882bee8c..58c2689c287c 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -875,6 +875,15 @@ int i915_gem_context_getparam_ioctl(struct drm_device *dev, void *data,
 	case I915_CONTEXT_PARAM_PRIORITY:
 		args->value = ctx->sched.priority;
 		break;
+	case I915_CONTEXT_PARAM_PREEMPT_TIMEOUT:
+		if (!(to_i915(dev)->caps.scheduler & I915_SCHEDULER_CAP_PREEMPTION))
+			ret = -ENODEV;
+		else if (args->size)
+			ret = -EINVAL;
+		else
+			args->value = ctx->preempt_timeout;
+		break;
+
 	default:
 		ret = -EINVAL;
 		break;
@@ -950,6 +959,19 @@ int i915_gem_context_setparam_ioctl(struct drm_device *dev, void *data,
 		}
 		break;
 
+	case I915_CONTEXT_PARAM_PREEMPT_TIMEOUT:
+		if (args->size)
+			ret = -EINVAL;
+		else if (args->value > U32_MAX)
+			ret = -EINVAL;
+		else if (!(to_i915(dev)->caps.scheduler & I915_SCHEDULER_CAP_PREEMPTION))
+			ret = -ENODEV;
+		else if (args->value && !capable(CAP_SYS_ADMIN))
+			ret = -EPERM;
+		else
+			ctx->preempt_timeout = args->value;
+		break;
+
 	default:
 		ret = -EINVAL;
 		break;
diff --git a/drivers/gpu/drm/i915/i915_gem_context.h b/drivers/gpu/drm/i915/i915_gem_context.h
index 834d3951d8a9..837d522e594c 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.h
+++ b/drivers/gpu/drm/i915/i915_gem_context.h
@@ -147,6 +147,19 @@ struct i915_gem_context {
 
 	struct i915_sched_attr sched;
 
+	/**
+	 * @preempt_timeout: QoS guarantee for the high priority context
+	 *
+	 * Some clients need a guarantee that they will start executing
+	 * within a certain window, even at the expense of others. This entails
+	 * that if a preemption request is not honoured by the active context
+	 * within the timeout, we will reset the GPU to evict the hog and
+	 * run the high priority context instead.
+	 *
+	 * Timeout is stored in nanoseconds.
+	 */
+	u32 preempt_timeout;
+
 	/** ggtt_offset_bias: placement restriction for context objects */
 	u32 ggtt_offset_bias;
 
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index b8b922f8977e..811595d32eb6 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -1127,8 +1127,11 @@ void i915_request_add(struct i915_request *request)
 	 */
 	local_bh_disable();
 	rcu_read_lock(); /* RCU serialisation for set-wedged protection */
-	if (engine->schedule)
-		engine->schedule(request, &request->gem_context->sched, 0);
+	if (engine->schedule) {
+		engine->schedule(request,
+				 &request->gem_context->sched,
+				 request->gem_context->preempt_timeout);
+	}
 	rcu_read_unlock();
 	i915_sw_fence_commit(&request->submit);
 	local_bh_enable(); /* Kick the execlists tasklet if just scheduled */
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 28c9fc6cb392..ba63a6384e93 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1266,20 +1266,20 @@ static void submit_queue(struct intel_engine_cs *engine,
 	}
 }
 
-static void execlists_submit_request(struct i915_request *request)
+static void execlists_submit_request(struct i915_request *rq)
 {
-	struct intel_engine_cs *engine = request->engine;
+	struct intel_engine_cs *engine = rq->engine;
 	unsigned long flags;
 
 	/* Will be called from irq-context when using foreign fences. */
 	spin_lock_irqsave(&engine->timeline.lock, flags);
 
-	queue_request(engine, &request->sched, rq_prio(request));
+	queue_request(engine, &rq->sched, rq_prio(rq));
 
 	GEM_BUG_ON(RB_EMPTY_ROOT(&engine->execlists.queue.rb_root));
-	GEM_BUG_ON(list_empty(&request->sched.link));
+	GEM_BUG_ON(list_empty(&rq->sched.link));
 
-	submit_queue(engine, rq_prio(request), 0);
+	submit_queue(engine, rq_prio(rq), rq->gem_context->preempt_timeout);
 
 	spin_unlock_irqrestore(&engine->timeline.lock, flags);
 }
diff --git a/drivers/gpu/drm/i915/selftests/intel_lrc.c b/drivers/gpu/drm/i915/selftests/intel_lrc.c
index 4a89662e7e07..12a33a8410ca 100644
--- a/drivers/gpu/drm/i915/selftests/intel_lrc.c
+++ b/drivers/gpu/drm/i915/selftests/intel_lrc.c
@@ -846,6 +846,90 @@ static int live_late_preempt_timeout(void *arg)
 	goto err_ctx_lo;
 }
 
+static int live_context_preempt_timeout(void *arg)
+{
+	struct drm_i915_private *i915 = arg;
+	struct i915_gem_context *ctx_hi, *ctx_lo;
+	struct spinner spin_hi, spin_lo;
+	struct intel_engine_cs *engine;
+	enum intel_engine_id id;
+	int err = -ENOMEM;
+
+	if (!HAS_LOGICAL_RING_PREEMPTION(i915))
+		return 0;
+
+	mutex_lock(&i915->drm.struct_mutex);
+
+	if (spinner_init(&spin_hi, i915))
+		goto err_unlock;
+
+	if (spinner_init(&spin_lo, i915))
+		goto err_spin_hi;
+
+	ctx_hi = kernel_context(i915);
+	if (!ctx_hi)
+		goto err_spin_lo;
+	ctx_hi->sched.priority = I915_CONTEXT_MAX_USER_PRIORITY;
+	ctx_hi->preempt_timeout = 50 * 1000; /* 50us */
+
+	ctx_lo = kernel_context(i915);
+	if (!ctx_lo)
+		goto err_ctx_hi;
+	ctx_lo->sched.priority = I915_CONTEXT_MIN_USER_PRIORITY;
+
+	for_each_engine(engine, i915, id) {
+		struct i915_request *rq;
+
+		rq = spinner_create_request(&spin_lo, ctx_lo, engine, MI_NOOP);
+		if (IS_ERR(rq)) {
+			err = PTR_ERR(rq);
+			goto err_ctx_lo;
+		}
+
+		i915_request_add(rq);
+		if (!wait_for_spinner(&spin_lo, rq)) {
+			i915_gem_set_wedged(i915);
+			err = -EIO;
+			goto err_ctx_lo;
+		}
+
+		rq = spinner_create_request(&spin_hi, ctx_hi, engine, MI_NOOP);
+		if (IS_ERR(rq)) {
+			spinner_end(&spin_lo);
+			err = PTR_ERR(rq);
+			goto err_ctx_lo;
+		}
+
+		i915_request_add(rq);
+		if (!wait_for_spinner(&spin_hi, rq)) {
+			i915_gem_set_wedged(i915);
+			err = -EIO;
+			goto err_ctx_lo;
+		}
+
+		spinner_end(&spin_hi);
+		spinner_end(&spin_lo);
+		if (igt_flush_test(i915, I915_WAIT_LOCKED)) {
+			err = -EIO;
+			goto err_ctx_lo;
+		}
+	}
+
+	err = 0;
+err_ctx_lo:
+	kernel_context_close(ctx_lo);
+err_ctx_hi:
+	kernel_context_close(ctx_hi);
+err_spin_lo:
+	spinner_fini(&spin_lo);
+err_spin_hi:
+	spinner_fini(&spin_hi);
+err_unlock:
+	igt_flush_test(i915, I915_WAIT_LOCKED);
+	mutex_unlock(&i915->drm.struct_mutex);
+	return err;
+}
+
 int intel_execlists_live_selftests(struct drm_i915_private *i915)
 {
 	static const struct i915_subtest tests[] = {
@@ -856,6 +940,7 @@ int intel_execlists_live_selftests(struct drm_i915_private *i915)
 		SUBTEST(live_preempt_timeout),
 		SUBTEST(live_preempt_reset),
 		SUBTEST(live_late_preempt_timeout),
+		SUBTEST(live_context_preempt_timeout),
 	};
 
 	if (!HAS_EXECLISTS(i915))
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index a25ed4719921..d66e8765f6af 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -1459,6 +1459,18 @@ struct drm_i915_gem_context_param {
 #define   I915_CONTEXT_MAX_USER_PRIORITY	1023 /* inclusive */
 #define   I915_CONTEXT_DEFAULT_PRIORITY		0
 #define   I915_CONTEXT_MIN_USER_PRIORITY	-1023 /* inclusive */
+
+/*
+ * I915_CONTEXT_PARAM_PREEMPT_TIMEOUT:
+ *
+ * Preemption timeout give in nanoseconds.
+ *
+ * Only allowed for privileged clients (CAP_SYS_ADMIN), this property allows
+ * the preempting context to kick out a GPU hog using a GPU reset if they do
+ * not honour our preemption request in time.
+ */
+#define I915_CONTEXT_PARAM_PREEMPT_TIMEOUT	0x7
+
 	__u64 value;
 };
 
-- 
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