1 files changed, 82 insertions, 17 deletions

diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index a32aabce7901..724b2cb897d3 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -182,6 +182,7 @@
 struct virtual_engine {
 	struct intel_engine_cs base;
 	struct intel_context context;
+	struct rcu_work rcu;
 
 	/*
 	 * We allow only a single request through the virtual engine at a time
@@ -2787,6 +2788,9 @@ static void __execlists_hold(struct i915_request *rq)
 static bool execlists_hold(struct intel_engine_cs *engine,
 			   struct i915_request *rq)
 {
+	if (i915_request_on_hold(rq))
+		return false;
+
 	spin_lock_irq(&engine->active.lock);
 
 	if (i915_request_completed(rq)) { /* too late! */
@@ -3168,8 +3172,10 @@ static void execlists_submission_tasklet(unsigned long data)
 		spin_unlock_irqrestore(&engine->active.lock, flags);
 
 		/* Recheck after serialising with direct-submission */
-		if (unlikely(timeout && preempt_timeout(engine)))
+		if (unlikely(timeout && preempt_timeout(engine))) {
+			cancel_timer(&engine->execlists.preempt);
 			execlists_reset(engine, "preemption time out");
+		}
 	}
 }
 
@@ -3547,6 +3553,19 @@ static const struct intel_context_ops execlists_context_ops = {
 	.destroy = execlists_context_destroy,
 };
 
+static u32 hwsp_offset(const struct i915_request *rq)
+{
+	const struct intel_timeline_cacheline *cl;
+
+	/* Before the request is executed, the timeline/cachline is fixed */
+
+	cl = rcu_dereference_protected(rq->hwsp_cacheline, 1);
+	if (cl)
+		return cl->ggtt_offset;
+
+	return rcu_dereference_protected(rq->timeline, 1)->hwsp_offset;
+}
+
 static int gen8_emit_init_breadcrumb(struct i915_request *rq)
 {
 	u32 *cs;
@@ -3569,7 +3588,7 @@ static int gen8_emit_init_breadcrumb(struct i915_request *rq)
 	*cs++ = MI_NOOP;
 
 	*cs++ = MI_STORE_DWORD_IMM_GEN4 | MI_USE_GGTT;
-	*cs++ = i915_request_timeline(rq)->hwsp_offset;
+	*cs++ = hwsp_offset(rq);
 	*cs++ = 0;
 	*cs++ = rq->fence.seqno - 1;
 
@@ -4886,11 +4905,9 @@ gen8_emit_fini_breadcrumb_tail(struct i915_request *request, u32 *cs)
 	return gen8_emit_wa_tail(request, cs);
 }
 
-static u32 *emit_xcs_breadcrumb(struct i915_request *request, u32 *cs)
+static u32 *emit_xcs_breadcrumb(struct i915_request *rq, u32 *cs)
 {
-	u32 addr = i915_request_active_timeline(request)->hwsp_offset;
-
-	return gen8_emit_ggtt_write(cs, request->fence.seqno, addr, 0);
+	return gen8_emit_ggtt_write(cs, rq->fence.seqno, hwsp_offset(rq), 0);
 }
 
 static u32 *gen8_emit_fini_breadcrumb(struct i915_request *rq, u32 *cs)
@@ -4909,7 +4926,7 @@ static u32 *gen8_emit_fini_breadcrumb_rcs(struct i915_request *request, u32 *cs)
 	/* XXX flush+write+CS_STALL all in one upsets gem_concurrent_blt:kbl */
 	cs = gen8_emit_ggtt_write_rcs(cs,
 				      request->fence.seqno,
-				      i915_request_active_timeline(request)->hwsp_offset,
+				      hwsp_offset(request),
 				      PIPE_CONTROL_FLUSH_ENABLE |
 				      PIPE_CONTROL_CS_STALL);
 
@@ -4921,7 +4938,7 @@ gen11_emit_fini_breadcrumb_rcs(struct i915_request *request, u32 *cs)
 {
 	cs = gen8_emit_ggtt_write_rcs(cs,
 				      request->fence.seqno,
-				      i915_request_active_timeline(request)->hwsp_offset,
+				      hwsp_offset(request),
 				      PIPE_CONTROL_CS_STALL |
 				      PIPE_CONTROL_TILE_CACHE_FLUSH |
 				      PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH |
@@ -4983,7 +5000,9 @@ gen12_emit_fini_breadcrumb_tail(struct i915_request *request, u32 *cs)
 
 static u32 *gen12_emit_fini_breadcrumb(struct i915_request *rq, u32 *cs)
 {
-	return gen12_emit_fini_breadcrumb_tail(rq, emit_xcs_breadcrumb(rq, cs));
+	/* XXX Stalling flush before seqno write; post-sync not */
+	cs = emit_xcs_breadcrumb(rq, __gen8_emit_flush_dw(cs, 0, 0, 0));
+	return gen12_emit_fini_breadcrumb_tail(rq, cs);
 }
 
 static u32 *
@@ -4991,7 +5010,7 @@ gen12_emit_fini_breadcrumb_rcs(struct i915_request *request, u32 *cs)
 {
 	cs = gen12_emit_ggtt_write_rcs(cs,
 				       request->fence.seqno,
-				       i915_request_active_timeline(request)->hwsp_offset,
+				       hwsp_offset(request),
 				       PIPE_CONTROL0_HDC_PIPELINE_FLUSH,
 				       PIPE_CONTROL_CS_STALL |
 				       PIPE_CONTROL_TILE_CACHE_FLUSH |
@@ -5412,44 +5431,90 @@ static struct list_head *virtual_queue(struct virtual_engine *ve)
 	return &ve->base.execlists.default_priolist.requests[0];
 }
 
-static void virtual_context_destroy(struct kref *kref)
+static void rcu_virtual_context_destroy(struct work_struct *wrk)
 {
 	struct virtual_engine *ve =
-		container_of(kref, typeof(*ve), context.ref);
+		container_of(wrk, typeof(*ve), rcu.work);
 	unsigned int n;
 
-	GEM_BUG_ON(!list_empty(virtual_queue(ve)));
-	GEM_BUG_ON(ve->request);
 	GEM_BUG_ON(ve->context.inflight);
 
+	/* Preempt-to-busy may leave a stale request behind. */
+	if (unlikely(ve->request)) {
+		struct i915_request *old;
+
+		spin_lock_irq(&ve->base.active.lock);
+
+		old = fetch_and_zero(&ve->request);
+		if (old) {
+			GEM_BUG_ON(!i915_request_completed(old));
+			__i915_request_submit(old);
+			i915_request_put(old);
+		}
+
+		spin_unlock_irq(&ve->base.active.lock);
+	}
+
+	/*
+	 * Flush the tasklet in case it is still running on another core.
+	 *
+	 * This needs to be done before we remove ourselves from the siblings'
+	 * rbtrees as in the case it is running in parallel, it may reinsert
+	 * the rb_node into a sibling.
+	 */
+	tasklet_kill(&ve->base.execlists.tasklet);
+
+	/* Decouple ourselves from the siblings, no more access allowed. */
 	for (n = 0; n < ve->num_siblings; n++) {
 		struct intel_engine_cs *sibling = ve->siblings[n];
 		struct rb_node *node = &ve->nodes[sibling->id].rb;
-		unsigned long flags;
 
 		if (RB_EMPTY_NODE(node))
 			continue;
 
-		spin_lock_irqsave(&sibling->active.lock, flags);
+		spin_lock_irq(&sibling->active.lock);
 
 		/* Detachment is lazily performed in the execlists tasklet */
 		if (!RB_EMPTY_NODE(node))
 			rb_erase_cached(node, &sibling->execlists.virtual);
 
-		spin_unlock_irqrestore(&sibling->active.lock, flags);
+		spin_unlock_irq(&sibling->active.lock);
 	}
 	GEM_BUG_ON(__tasklet_is_scheduled(&ve->base.execlists.tasklet));
+	GEM_BUG_ON(!list_empty(virtual_queue(ve)));
 
 	if (ve->context.state)
 		__execlists_context_fini(&ve->context);
 	intel_context_fini(&ve->context);
 
+	intel_breadcrumbs_free(ve->base.breadcrumbs);
 	intel_engine_free_request_pool(&ve->base);
 
 	kfree(ve->bonds);
 	kfree(ve);
 }
 
+static void virtual_context_destroy(struct kref *kref)
+{
+	struct virtual_engine *ve =
+		container_of(kref, typeof(*ve), context.ref);
+
+	GEM_BUG_ON(!list_empty(&ve->context.signals));
+
+	/*
+	 * When destroying the virtual engine, we have to be aware that
+	 * it may still be in use from an hardirq/softirq context causing
+	 * the resubmission of a completed request (background completion
+	 * due to preempt-to-busy). Before we can free the engine, we need
+	 * to flush the submission code and tasklets that are still potentially
+	 * accessing the engine. Flushing the tasklets requires process context,
+	 * and since we can guard the resubmit onto the engine with an RCU read
+	 * lock, we can delegate the free of the engine to an RCU worker.
+	 */
+	INIT_RCU_WORK(&ve->rcu, rcu_virtual_context_destroy);
+	queue_rcu_work(system_wq, &ve->rcu);
+}
+
 static void virtual_engine_initial_hint(struct virtual_engine *ve)
 {
 	int swp;