drm/xe: Long running job update

For long running (LR) jobs with the DRM scheduler we must return NULL in
run_job which results in signaling the job's finished fence immediately.
This prevents LR jobs from creating infinite dma-fences.

Signaling job's finished fence immediately breaks flow controlling ring
with the DRM scheduler. To work around this, the ring is flow controlled
and written in the exec IOCTL. Signaling job's finished fence
immediately also breaks the TDR which is used in reset / cleanup entity
paths so write a new path for LR entities.

v2: Better commit, white space, remove rmb(), better comment next to
emit_job()
v3 (Thomas): Change LR reference counting, fix working in commit

Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/xe_engine.c

@@ -18,6 +18,7 @@
 #include "xe_macros.h"
 #include "xe_migrate.h"
 #include "xe_pm.h"
+#include "xe_ring_ops_types.h"
 #include "xe_trace.h"
 #include "xe_vm.h"
 
@@ -679,6 +680,37 @@ static void engine_kill_compute(struct xe_engine *e)
 	up_write(&e->vm->lock);
 }
 
+/**
+ * xe_engine_is_lr() - Whether an engine is long-running
+ * @e: The engine
+ *
+ * Return: True if the engine is long-running, false otherwise.
+ */
+bool xe_engine_is_lr(struct xe_engine *e)
+{
+	return e->vm && xe_vm_no_dma_fences(e->vm) &&
+		!(e->flags & ENGINE_FLAG_VM);
+}
+
+static s32 xe_engine_num_job_inflight(struct xe_engine *e)
+{
+	return e->lrc->fence_ctx.next_seqno - xe_lrc_seqno(e->lrc) - 1;
+}
+
+/**
+ * xe_engine_ring_full() - Whether an engine's ring is full
+ * @e: The engine
+ *
+ * Return: True if the engine's ring is full, false otherwise.
+ */
+bool xe_engine_ring_full(struct xe_engine *e)
+{
+	struct xe_lrc *lrc = e->lrc;
+	s32 max_job = lrc->ring.size / MAX_JOB_SIZE_BYTES;
+
+	return xe_engine_num_job_inflight(e) >= max_job;
+}
+
 /**
  * xe_engine_is_idle() - Whether an engine is idle.
  * @engine: The engine

drivers/gpu/drm/xe/xe_engine.h

@@ -42,6 +42,10 @@ static inline bool xe_engine_is_parallel(struct xe_engine *engine)
 	return engine->width > 1;
 }
 
+bool xe_engine_is_lr(struct xe_engine *e);
+
+bool xe_engine_ring_full(struct xe_engine *e);
+
 bool xe_engine_is_idle(struct xe_engine *engine);
 
 void xe_engine_kill(struct xe_engine *e);

drivers/gpu/drm/xe/xe_exec.c

@@ -14,6 +14,7 @@
 #include "xe_device.h"
 #include "xe_engine.h"
 #include "xe_macros.h"
+#include "xe_ring_ops_types.h"
 #include "xe_sched_job.h"
 #include "xe_sync.h"
 #include "xe_vm.h"
@@ -302,6 +303,11 @@ int xe_exec_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
 		goto err_engine_end;
 	}
 
+	if (xe_engine_is_lr(engine) && xe_engine_ring_full(engine)) {
+		err = -EWOULDBLOCK;
+		goto err_engine_end;
+	}
+
 	job = xe_sched_job_create(engine, xe_engine_is_parallel(engine) ?
 				  addresses : &args->address);
 	if (IS_ERR(job)) {
@@ -388,6 +394,8 @@ int xe_exec_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
 		xe_sync_entry_signal(&syncs[i], job,
 				     &job->drm.s_fence->finished);
 
+	if (xe_engine_is_lr(engine))
+		engine->ring_ops->emit_job(job);
 	xe_sched_job_push(job);
 	xe_vm_reactivate_rebind(vm);
 

drivers/gpu/drm/xe/xe_guc_engine_types.h

@@ -31,6 +31,8 @@ struct xe_guc_engine {
 	 */
 #define MAX_STATIC_MSG_TYPE	3
 	struct xe_sched_msg static_msgs[MAX_STATIC_MSG_TYPE];
+	/** @lr_tdr: long running TDR worker */
+	struct work_struct lr_tdr;
 	/** @fini_async: do final fini async from this worker */
 	struct work_struct fini_async;
 	/** @resume_time: time of last resume */

drivers/gpu/drm/xe/xe_guc_submit.c

@@ -483,6 +483,14 @@ static void register_engine(struct xe_engine *e)
 		parallel_write(xe, map, wq_desc.wq_status, WQ_STATUS_ACTIVE);
 	}
 
+	/*
+	 * We must keep a reference for LR engines if engine is registered with
+	 * the GuC as jobs signal immediately and can't destroy an engine if the
+	 * GuC has a reference to it.
+	 */
+	if (xe_engine_is_lr(e))
+		xe_engine_get(e);
+
 	set_engine_registered(e);
 	trace_xe_engine_register(e);
 	if (xe_engine_is_parallel(e))
@@ -645,6 +653,7 @@ guc_engine_run_job(struct drm_sched_job *drm_job)
 {
 	struct xe_sched_job *job = to_xe_sched_job(drm_job);
 	struct xe_engine *e = job->engine;
+	bool lr = xe_engine_is_lr(e);
 
 	XE_BUG_ON((engine_destroyed(e) || engine_pending_disable(e)) &&
 		  !engine_banned(e) && !engine_suspended(e));
@@ -654,14 +663,19 @@ guc_engine_run_job(struct drm_sched_job *drm_job)
 	if (!engine_killed_or_banned(e) && !xe_sched_job_is_error(job)) {
 		if (!engine_registered(e))
 			register_engine(e);
-		e->ring_ops->emit_job(job);
+		if (!lr)	/* LR jobs are emitted in the exec IOCTL */
+			e->ring_ops->emit_job(job);
 		submit_engine(e);
 	}
 
-	if (test_and_set_bit(JOB_FLAG_SUBMIT, &job->fence->flags))
+	if (lr) {
+		xe_sched_job_set_error(job, -EOPNOTSUPP);
+		return NULL;
+	} else if (test_and_set_bit(JOB_FLAG_SUBMIT, &job->fence->flags)) {
 		return job->fence;
-	else
+	} else {
 		return dma_fence_get(job->fence);
+	}
 }
 
 static void guc_engine_free_job(struct drm_sched_job *drm_job)
@@ -764,6 +778,55 @@ static void simple_error_capture(struct xe_engine *e)
 }
 #endif
 
+static void xe_guc_engine_trigger_cleanup(struct xe_engine *e)
+{
+	struct xe_guc *guc = engine_to_guc(e);
+
+	if (xe_engine_is_lr(e))
+		queue_work(guc_to_gt(guc)->ordered_wq, &e->guc->lr_tdr);
+	else
+		xe_sched_tdr_queue_imm(&e->guc->sched);
+}
+
+static void xe_guc_engine_lr_cleanup(struct work_struct *w)
+{
+	struct xe_guc_engine *ge =
+		container_of(w, struct xe_guc_engine, lr_tdr);
+	struct xe_engine *e = ge->engine;
+	struct xe_gpu_scheduler *sched = &ge->sched;
+
+	XE_WARN_ON(!xe_engine_is_lr(e));
+	trace_xe_engine_lr_cleanup(e);
+
+	/* Kill the run_job / process_msg entry points */
+	xe_sched_submission_stop(sched);
+
+	/* Engine state now stable, disable scheduling / deregister if needed */
+	if (engine_registered(e)) {
+		struct xe_guc *guc = engine_to_guc(e);
+		int ret;
+
+		set_engine_banned(e);
+		disable_scheduling_deregister(guc, e);
+
+		/*
+		 * Must wait for scheduling to be disabled before signalling
+		 * any fences, if GT broken the GT reset code should signal us.
+		 */
+		ret = wait_event_timeout(guc->ct.wq,
+					 !engine_pending_disable(e) ||
+					 guc_read_stopped(guc), HZ * 5);
+		if (!ret) {
+			XE_WARN_ON("Schedule disable failed to respond");
+			xe_sched_submission_start(sched);
+			xe_gt_reset_async(e->gt);
+			return;
+		}
+	}
+
+	xe_sched_submission_start(sched);
+}
+
 static enum drm_gpu_sched_stat
 guc_engine_timedout_job(struct drm_sched_job *drm_job)
 {
@@ -815,7 +878,7 @@ guc_engine_timedout_job(struct drm_sched_job *drm_job)
 			err = -EIO;
 		set_engine_banned(e);
 		xe_engine_get(e);
-		disable_scheduling_deregister(engine_to_guc(e), e);
+		disable_scheduling_deregister(guc, e);
 
 		/*
 		 * Must wait for scheduling to be disabled before signalling
@@ -848,7 +911,7 @@ guc_engine_timedout_job(struct drm_sched_job *drm_job)
 	 */
 	xe_sched_add_pending_job(sched, job);
 	xe_sched_submission_start(sched);
-	xe_sched_tdr_queue_imm(&e->guc->sched);
+	xe_guc_engine_trigger_cleanup(e);
 
 	/* Mark all outstanding jobs as bad, thus completing them */
 	spin_lock(&sched->base.job_list_lock);
@@ -872,6 +935,8 @@ static void __guc_engine_fini_async(struct work_struct *w)
 
 	trace_xe_engine_destroy(e);
 
+	if (xe_engine_is_lr(e))
+		cancel_work_sync(&ge->lr_tdr);
 	if (e->flags & ENGINE_FLAG_PERSISTENT)
 		xe_device_remove_persistent_engines(gt_to_xe(e->gt), e);
 	release_guc_id(guc, e);
@@ -889,7 +954,7 @@ static void guc_engine_fini_async(struct xe_engine *e)
 	bool kernel = e->flags & ENGINE_FLAG_KERNEL;
 
 	INIT_WORK(&e->guc->fini_async, __guc_engine_fini_async);
-	queue_work(system_unbound_wq, &e->guc->fini_async);
+	queue_work(system_wq, &e->guc->fini_async);
 
 	/* We must block on kernel engines so slabs are empty on driver unload */
 	if (kernel) {
@@ -1080,6 +1145,9 @@ static int guc_engine_init(struct xe_engine *e)
 		goto err_sched;
 	e->priority = XE_ENGINE_PRIORITY_NORMAL;
 
+	if (xe_engine_is_lr(e))
+		INIT_WORK(&e->guc->lr_tdr, xe_guc_engine_lr_cleanup);
+
 	mutex_lock(&guc->submission_state.lock);
 
 	err = alloc_guc_id(guc, e);
@@ -1131,7 +1199,7 @@ static void guc_engine_kill(struct xe_engine *e)
 {
 	trace_xe_engine_kill(e);
 	set_engine_killed(e);
-	xe_sched_tdr_queue_imm(&e->guc->sched);
+	xe_guc_engine_trigger_cleanup(e);
 }
 
 static void guc_engine_add_msg(struct xe_engine *e, struct xe_sched_msg *msg,
@@ -1283,10 +1351,11 @@ static void guc_engine_stop(struct xe_guc *guc, struct xe_engine *e)
 	xe_sched_submission_stop(sched);
 
 	/* Clean up lost G2H + reset engine state */
-	if (engine_destroyed(e) && engine_registered(e)) {
-		if (engine_banned(e))
+	if (engine_registered(e)) {
+		if ((engine_banned(e) && engine_destroyed(e)) ||
+		    xe_engine_is_lr(e))
 			xe_engine_put(e);
-		else
+		else if (engine_destroyed(e))
 			__guc_engine_fini(guc, e);
 	}
 	if (e->guc->suspend_pending) {
@@ -1501,7 +1570,8 @@ int xe_guc_deregister_done_handler(struct xe_guc *guc, u32 *msg, u32 len)
 	trace_xe_engine_deregister_done(e);
 
 	clear_engine_registered(e);
-	if (engine_banned(e))
+
+	if (engine_banned(e) || xe_engine_is_lr(e))
 		xe_engine_put(e);
 	else
 		__guc_engine_fini(guc, e);
@@ -1538,7 +1608,7 @@ int xe_guc_engine_reset_handler(struct xe_guc *guc, u32 *msg, u32 len)
 	 */
 	set_engine_reset(e);
 	if (!engine_banned(e))
-		xe_sched_tdr_queue_imm(&e->guc->sched);
+		xe_guc_engine_trigger_cleanup(e);
 
 	return 0;
 }
@@ -1565,7 +1635,7 @@ int xe_guc_engine_memory_cat_error_handler(struct xe_guc *guc, u32 *msg,
 	/* Treat the same as engine reset */
 	set_engine_reset(e);
 	if (!engine_banned(e))
-		xe_sched_tdr_queue_imm(&e->guc->sched);
+		xe_guc_engine_trigger_cleanup(e);
 
 	return 0;
 }

drivers/gpu/drm/xe/xe_trace.h

@@ -220,6 +220,11 @@ DEFINE_EVENT(xe_engine, xe_engine_resubmit,
 	     TP_ARGS(e)
 );
 
+DEFINE_EVENT(xe_engine, xe_engine_lr_cleanup,
+	     TP_PROTO(struct xe_engine *e),
+	     TP_ARGS(e)
+);
+
 DECLARE_EVENT_CLASS(xe_sched_job,
 		    TP_PROTO(struct xe_sched_job *job),
 		    TP_ARGS(job),