[PATCH 07/13] drm/i915: Update reset path to fix incomplete requests

[Chris Wilson <chris@chris-wilson.co.uk>]

Update reset path in preparation for engine reset which requires
identification of incomplete requests and associated context and fixing
their state so that engine can resume correctly after reset.

The request that caused the hang will be skipped and head is reset to the
start of breadcrumb. This allows us to resume from where we left-off.
Since this request didn't complete normally we also need to cleanup elsp
queue manually. This is vital if we employ nonblocking request
submission where we may have a web of dependencies upon the hung request
and so advancing the seqno manually is no longer trivial.

Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Arun Siluvery <arun.siluvery@linux.intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_drv.c         |   4 +-
 drivers/gpu/drm/i915/i915_drv.h         |   2 +-
 drivers/gpu/drm/i915/i915_gem.c         | 106 +++++++++++++++-----------------
 drivers/gpu/drm/i915/i915_gem_context.c |  16 -----
 drivers/gpu/drm/i915/intel_lrc.c        |  34 +++++++++-
 drivers/gpu/drm/i915/intel_ringbuffer.c |  33 ++++++----
 drivers/gpu/drm/i915/intel_ringbuffer.h |   2 +
 7 files changed, 110 insertions(+), 87 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index fc9273215286..af3c46eadd1a 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1590,7 +1590,7 @@ static int i915_drm_resume(struct drm_device *dev)
 	mutex_lock(&dev->struct_mutex);
 	if (i915_gem_init_hw(dev)) {
 		DRM_ERROR("failed to re-initialize GPU, declaring wedged!\n");
-		atomic_or(I915_WEDGED, &dev_priv->gpu_error.reset_counter);
+		i915_gem_set_wedged(dev_priv);
 	}
 	mutex_unlock(&dev->struct_mutex);
 
@@ -1816,7 +1816,7 @@ int i915_reset(struct drm_i915_private *dev_priv)
 	return 0;
 
 error:
-	atomic_or(I915_WEDGED, &error->reset_counter);
+	i915_gem_set_wedged(dev_priv);
 	mutex_unlock(&dev->struct_mutex);
 	return ret;
 }
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index ff96b7a69e6c..03eff38bc081 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -3269,6 +3269,7 @@ static inline u32 i915_reset_count(struct i915_gpu_error *error)
 }
 
 void i915_gem_reset(struct drm_device *dev);
+void i915_gem_set_wedged(struct drm_i915_private *dev_priv);
 bool i915_gem_clflush_object(struct drm_i915_gem_object *obj, bool force);
 int __must_check i915_gem_init(struct drm_device *dev);
 int __must_check i915_gem_init_hw(struct drm_device *dev);
@@ -3397,7 +3398,6 @@ void i915_gem_object_save_bit_17_swizzle(struct drm_i915_gem_object *obj);
 int __must_check i915_gem_context_init(struct drm_device *dev);
 void i915_gem_context_lost(struct drm_i915_private *dev_priv);
 void i915_gem_context_fini(struct drm_device *dev);
-void i915_gem_context_reset(struct drm_device *dev);
 int i915_gem_context_open(struct drm_device *dev, struct drm_file *file);
 void i915_gem_context_close(struct drm_device *dev, struct drm_file *file);
 int i915_switch_context(struct drm_i915_gem_request *req);
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 23ac08819950..265149711af6 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2501,34 +2501,68 @@ i915_gem_find_active_request(struct intel_engine_cs *engine)
 	return NULL;
 }
 
-static void i915_gem_reset_engine_status(struct intel_engine_cs *engine)
+static void i915_gem_reset_engine(struct intel_engine_cs *engine)
 {
 	struct drm_i915_gem_request *request;
+	struct i915_gem_context *incomplete_ctx;
+	unsigned long flags;
 	bool ring_hung;
 
+	/* Ensure irq handler finishes or is cancelled, and not run again. */
+	local_irq_save(flags);
+	tasklet_kill(&engine->irq_tasklet);
+	tasklet_disable(&engine->irq_tasklet);
+	local_irq_restore(flags);
+
 	request = i915_gem_find_active_request(engine);
-	if (request == NULL)
-		return;
+	if (!request)
+		goto out;
 
 	ring_hung = engine->hangcheck.score >= HANGCHECK_SCORE_RING_HUNG;
 
 	i915_set_reset_status(request->ctx, ring_hung);
-	list_for_each_entry_continue(request, &engine->request_list, link)
+
+	engine->reset_hw(engine, request);
+
+	incomplete_ctx = request->ctx;
+	if (i915_gem_context_is_default(incomplete_ctx))
+		incomplete_ctx = NULL;
+
+	list_for_each_entry_continue(request, &engine->request_list, link) {
+		void *vaddr = request->ring->vaddr;
+		u32 head;
+
+		if (request->ctx != incomplete_ctx)
+			continue;
+
+		head = request->head;
+		if (request->postfix < head) {
+			memset(vaddr + head, 0, request->ring->size - head);
+			head = 0;
+		}
+		memset(vaddr + head, 0, request->postfix - head);
+
 		i915_set_reset_status(request->ctx, false);
+	}
+
+out:
+	tasklet_enable(&engine->irq_tasklet);
 }
 
-static void i915_gem_reset_engine_cleanup(struct intel_engine_cs *engine)
+void i915_gem_reset(struct drm_device *dev)
 {
-	struct drm_i915_gem_request *request;
-	unsigned long flags;
-	struct intel_ring *ring;
+	struct drm_i915_private *dev_priv = to_i915(dev);
+	struct intel_engine_cs *engine;
 
-	/* Ensure irq handler finishes or is cancelled, and not run again. */
-	local_irq_save(flags);
-	tasklet_kill(&engine->irq_tasklet);
-	tasklet_disable(&engine->irq_tasklet);
-	local_irq_restore(flags);
+	for_each_engine(engine, dev_priv)
+		i915_gem_reset_engine(engine);
 
+	i915_gem_context_lost(dev_priv);
+	i915_gem_restore_fences(dev);
+}
+
+static void i915_gem_cleanup_engine(struct intel_engine_cs *engine)
+{
 	/* Mark all pending requests as complete so that any concurrent
 	 * (lockless) lookup doesn't try and wait upon the request as we
 	 * reset it.
@@ -2550,56 +2584,18 @@ static void i915_gem_reset_engine_cleanup(struct intel_engine_cs *engine)
 		spin_unlock(&engine->execlist_lock);
 	}
 
-	/*
-	 * We must free the requests after all the corresponding objects have
-	 * been moved off active lists. Which is the same order as the normal
-	 * retire_requests function does. This is important if object hold
-	 * implicit references on things like e.g. ppgtt address spaces through
-	 * the request.
-	 */
-	request = i915_gem_active_raw(&engine->last_request,
-				      &engine->i915->drm.struct_mutex);
-	if (request)
-		i915_gem_request_retire_upto(request);
-	GEM_BUG_ON(intel_engine_is_active(engine));
-
-	/* Having flushed all requests from all queues, we know that all
-	 * ringbuffers must now be empty. However, since we do not reclaim
-	 * all space when retiring the request (to prevent HEADs colliding
-	 * with rapid ringbuffer wraparound) the amount of available space
-	 * upon reset is less than when we start. Do one more pass over
-	 * all the ringbuffers to reset last_retired_head.
-	 */
-	list_for_each_entry(ring, &engine->buffers, link) {
-		ring->last_retired_head = ring->tail;
-		intel_ring_update_space(ring);
-	}
-
 	engine->i915->gt.active_engines &= ~intel_engine_flag(engine);
-
-	tasklet_enable(&engine->irq_tasklet);
 }
 
-void i915_gem_reset(struct drm_device *dev)
+void i915_gem_set_wedged(struct drm_i915_private *dev_priv)
 {
-	struct drm_i915_private *dev_priv = to_i915(dev);
 	struct intel_engine_cs *engine;
 
-	/*
-	 * Before we free the objects from the requests, we need to inspect
-	 * them for finding the guilty party. As the requests only borrow
-	 * their reference to the objects, the inspection must be done first.
-	 */
-	for_each_engine(engine, dev_priv)
-		i915_gem_reset_engine_status(engine);
+	atomic_or(I915_WEDGED, &dev_priv->gpu_error.reset_counter);
 
 	for_each_engine(engine, dev_priv)
-		i915_gem_reset_engine_cleanup(engine);
+		i915_gem_cleanup_engine(engine);
 	mod_delayed_work(dev_priv->wq, &dev_priv->gt.idle_work, 0);
-
-	i915_gem_context_reset(dev);
-
-	i915_gem_restore_fences(dev);
 }
 
 static void
@@ -4478,7 +4474,7 @@ int i915_gem_init(struct drm_device *dev)
 		 * for all other failure, such as an allocation failure, bail.
 		 */
 		DRM_ERROR("Failed to initialize GPU, declaring it wedged\n");
-		atomic_or(I915_WEDGED, &dev_priv->gpu_error.reset_counter);
+		i915_gem_set_wedged(dev_priv);
 		ret = 0;
 	}
 
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 35950ee46a1d..df10f4e95736 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -420,22 +420,6 @@ static void i915_gem_context_unpin(struct i915_gem_context *ctx,
 	}
 }
 
-void i915_gem_context_reset(struct drm_device *dev)
-{
-	struct drm_i915_private *dev_priv = to_i915(dev);
-
-	lockdep_assert_held(&dev->struct_mutex);
-
-	if (i915.enable_execlists) {
-		struct i915_gem_context *ctx;
-
-		list_for_each_entry(ctx, &dev_priv->context_list, link)
-			intel_lr_context_reset(dev_priv, ctx);
-	}
-
-	i915_gem_context_lost(dev_priv);
-}
-
 int i915_gem_context_init(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 325c1273450f..5e60519ede8d 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1171,6 +1171,7 @@ static int gen8_init_common_ring(struct intel_engine_cs *engine)
 {
 	struct drm_i915_private *dev_priv = engine->i915;
 
+	intel_mocs_init_engine(engine);
 	lrc_init_hws(engine);
 
 	I915_WRITE_IMR(engine,
@@ -1190,7 +1191,10 @@ static int gen8_init_common_ring(struct intel_engine_cs *engine)
 
 	intel_engine_init_hangcheck(engine);
 
-	return intel_mocs_init_engine(engine);
+	if (engine->execlist_port[0].request)
+		execlists_submit_ports(engine);
+
+	return 0;
 }
 
 static int gen8_init_render_ring(struct intel_engine_cs *engine)
@@ -1226,6 +1230,33 @@ static int gen9_init_render_ring(struct intel_engine_cs *engine)
 	return init_workarounds_ring(engine);
 }
 
+static void reset_common_ring(struct intel_engine_cs *engine,
+			      struct drm_i915_gem_request *request)
+{
+	struct drm_i915_private *dev_priv = engine->i915;
+	struct i915_gem_context *ctx = request->ctx;
+	struct intel_context *ce = &ctx->engine[engine->id];
+	u32 *reg_state;
+
+	reg_state = ce->lrc_reg_state;
+	reg_state[CTX_RING_HEAD+1] = request->postfix;
+
+	request->ring->head = request->postfix;
+	request->ring->last_retired_head = -1;
+	intel_ring_update_space(request->ring);
+
+	if (request == engine->execlist_port[1].request) {
+		i915_gem_request_put(engine->execlist_port[0].request);
+		engine->execlist_port[0] = engine->execlist_port[1];
+		memset(&engine->execlist_port[1], 0,
+		       sizeof(engine->execlist_port[1]));
+	}
+
+	engine->execlist_port[0].count = 0;
+
+	I915_WRITE(RING_CONTEXT_STATUS_PTR(engine), _MASKED_FIELD(0xffff, 0));
+}
+
 static int intel_logical_ring_emit_pdps(struct drm_i915_gem_request *req)
 {
 	struct i915_hw_ppgtt *ppgtt = req->ctx->ppgtt;
@@ -1588,6 +1619,7 @@ logical_ring_default_vfuncs(struct intel_engine_cs *engine)
 {
 	/* Default vfuncs which can be overriden by each engine. */
 	engine->init_hw = gen8_init_common_ring;
+	engine->reset_hw = reset_common_ring;
 	engine->emit_flush = gen8_emit_flush;
 	engine->emit_request = gen8_emit_request;
 	engine->submit_request = execlists_submit_request;
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index cc5bcd14b6df..f0a5c6e9b908 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -577,34 +577,33 @@ static int init_ring_common(struct intel_engine_cs *engine)
 	if (I915_READ_HEAD(engine))
 		DRM_DEBUG("%s initialization failed [head=%08x], fudging\n",
 			  engine->name, I915_READ_HEAD(engine));
-	I915_WRITE_HEAD(engine, 0);
-	(void)I915_READ_HEAD(engine);
+
+	intel_ring_update_space(ring);
+	I915_WRITE_HEAD(engine, ring->head);
+	I915_WRITE_TAIL(engine, ring->tail);
+	(void)I915_READ_TAIL(engine);
 
 	I915_WRITE_CTL(engine,
 			((ring->size - PAGE_SIZE) & RING_NR_PAGES)
 			| RING_VALID);
 
 	/* If the head is still not zero, the ring is dead */
-	if (wait_for((I915_READ_CTL(engine) & RING_VALID) != 0 &&
-		     I915_READ_START(engine) == i915_ggtt_offset(ring->vma) &&
-		     (I915_READ_HEAD(engine) & HEAD_ADDR) == 0, 50)) {
+	if (intel_wait_for_register_fw(dev_priv, RING_CTL(engine->mmio_base),
+				       RING_VALID, RING_VALID,
+				       50)) {
 		DRM_ERROR("%s initialization failed "
-			  "ctl %08x (valid? %d) head %08x tail %08x start %08x [expected %08x]\n",
+			  "ctl %08x (valid? %d) head %08x [%08x] tail %08x [%08x] start %08x [expected %08x]\n",
 			  engine->name,
 			  I915_READ_CTL(engine),
 			  I915_READ_CTL(engine) & RING_VALID,
-			  I915_READ_HEAD(engine), I915_READ_TAIL(engine),
+			  I915_READ_HEAD(engine), ring->head,
+			  I915_READ_TAIL(engine), ring->tail,
 			  I915_READ_START(engine),
 			  i915_ggtt_offset(ring->vma));
 		ret = -EIO;
 		goto out;
 	}
 
-	ring->last_retired_head = -1;
-	ring->head = I915_READ_HEAD(engine);
-	ring->tail = I915_READ_TAIL(engine) & TAIL_ADDR;
-	intel_ring_update_space(ring);
-
 	intel_engine_init_hangcheck(engine);
 
 out:
@@ -613,6 +612,15 @@ out:
 	return ret;
 }
 
+static void reset_ring_common(struct intel_engine_cs *engine,
+			      struct drm_i915_gem_request *request)
+{
+	struct intel_ring *ring = request->ring;
+
+	ring->head = request->postfix;
+	ring->last_retired_head = -1;
+}
+
 static int intel_ring_workarounds_emit(struct drm_i915_gem_request *req)
 {
 	struct intel_ring *ring = req->ring;
@@ -2655,6 +2663,7 @@ static void intel_ring_default_vfuncs(struct drm_i915_private *dev_priv,
 	intel_ring_init_semaphores(dev_priv, engine);
 
 	engine->init_hw = init_ring_common;
+	engine->reset_hw = reset_ring_common;
 
 	engine->emit_request = i9xx_emit_request;
 	if (i915.semaphores)
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 64cb7a7dc687..8d1b2fc3e485 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -211,6 +211,8 @@ struct intel_engine_cs {
 	void		(*irq_disable)(struct intel_engine_cs *engine);
 
 	int		(*init_hw)(struct intel_engine_cs *engine);
+	void		(*reset_hw)(struct intel_engine_cs *engine,
+				    struct drm_i915_gem_request *req);
 
 	int		(*init_context)(struct drm_i915_gem_request *req);
 
-- 
2.9.3

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