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summarize.go

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  • intel_context.c 10.83 KiB
    /*
     * SPDX-License-Identifier: MIT
     *
     * Copyright © 2019 Intel Corporation
     */
    
    #include "gem/i915_gem_context.h"
    #include "gem/i915_gem_pm.h"
    
    #include "i915_drv.h"
    #include "i915_globals.h"
    
    #include "intel_context.h"
    #include "intel_engine.h"
    #include "intel_engine_pm.h"
    #include "intel_ring.h"
    
    static struct i915_global_context {
    	struct i915_global base;
    	struct kmem_cache *slab_ce;
    } global;
    
    static struct intel_context *intel_context_alloc(void)
    {
    	return kmem_cache_zalloc(global.slab_ce, GFP_KERNEL);
    }
    
    static void rcu_context_free(struct rcu_head *rcu)
    {
    	struct intel_context *ce = container_of(rcu, typeof(*ce), rcu);
    
    	kmem_cache_free(global.slab_ce, ce);
    }
    
    void intel_context_free(struct intel_context *ce)
    {
    	call_rcu(&ce->rcu, rcu_context_free);
    }
    
    struct intel_context *
    intel_context_create(struct intel_engine_cs *engine)
    {
    	struct intel_context *ce;
    
    	ce = intel_context_alloc();
    	if (!ce)
    		return ERR_PTR(-ENOMEM);
    
    	intel_context_init(ce, engine);
    	return ce;
    }
    
    int intel_context_alloc_state(struct intel_context *ce)
    {
    	int err = 0;
    
    	if (mutex_lock_interruptible(&ce->pin_mutex))
    		return -EINTR;
    
    	if (!test_bit(CONTEXT_ALLOC_BIT, &ce->flags)) {
    		if (intel_context_is_banned(ce)) {
    			err = -EIO;
    			goto unlock;
    		}
    
    		err = ce->ops->alloc(ce);
    		if (unlikely(err))
    			goto unlock;
    
    		set_bit(CONTEXT_ALLOC_BIT, &ce->flags);
    	}
    
    unlock:
    	mutex_unlock(&ce->pin_mutex);
    	return err;
    }
    
    static int intel_context_active_acquire(struct intel_context *ce)
    {
    	int err;
    
    	__i915_active_acquire(&ce->active);
    
    	if (intel_context_is_barrier(ce))
    		return 0;
    
    	/* Preallocate tracking nodes */
    	err = i915_active_acquire_preallocate_barrier(&ce->active,
    						      ce->engine);
    	if (err)
    		i915_active_release(&ce->active);
    
    	return err;
    }
    
    static void intel_context_active_release(struct intel_context *ce)
    {
    	/* Nodes preallocated in intel_context_active() */
    	i915_active_acquire_barrier(&ce->active);
    	i915_active_release(&ce->active);
    }
    
    static int __context_pin_state(struct i915_vma *vma, struct i915_gem_ww_ctx *ww)
    {
    	unsigned int bias = i915_ggtt_pin_bias(vma) | PIN_OFFSET_BIAS;
    	int err;
    
    	err = i915_ggtt_pin(vma, ww, 0, bias | PIN_HIGH);
    	if (err)
    		return err;
    
    	err = i915_active_acquire(&vma->active);
    	if (err)
    		goto err_unpin;
    
    	/*
    	 * And mark it as a globally pinned object to let the shrinker know
    	 * it cannot reclaim the object until we release it.
    	 */
    	i915_vma_make_unshrinkable(vma);
    	vma->obj->mm.dirty = true;
    
    	return 0;
    
    err_unpin:
    	i915_vma_unpin(vma);
    	return err;
    }
    
    static void __context_unpin_state(struct i915_vma *vma)
    {
    	i915_vma_make_shrinkable(vma);
    	i915_active_release(&vma->active);
    	__i915_vma_unpin(vma);
    }
    
    static int __ring_active(struct intel_ring *ring,
    			 struct i915_gem_ww_ctx *ww)
    {
    	int err;
    
    	err = intel_ring_pin(ring, ww);
    	if (err)
    		return err;
    
    	err = i915_active_acquire(&ring->vma->active);
    	if (err)
    		goto err_pin;
    
    	return 0;
    
    err_pin:
    	intel_ring_unpin(ring);
    	return err;
    }
    
    static void __ring_retire(struct intel_ring *ring)
    {
    	i915_active_release(&ring->vma->active);
    	intel_ring_unpin(ring);
    }
    
    static int intel_context_pre_pin(struct intel_context *ce,
    				 struct i915_gem_ww_ctx *ww)
    {
    	int err;
    
    	CE_TRACE(ce, "active\n");
    
    	err = __ring_active(ce->ring, ww);
    	if (err)
    		return err;
    
    	err = intel_timeline_pin(ce->timeline, ww);
    	if (err)
    		goto err_ring;
    
    	if (!ce->state)
    		return 0;
    
    	err = __context_pin_state(ce->state, ww);
    	if (err)
    		goto err_timeline;
    
    
    	return 0;
    
    err_timeline:
    	intel_timeline_unpin(ce->timeline);
    err_ring:
    	__ring_retire(ce->ring);
    	return err;
    }
    
    static void intel_context_post_unpin(struct intel_context *ce)
    {
    	if (ce->state)
    		__context_unpin_state(ce->state);
    
    	intel_timeline_unpin(ce->timeline);
    	__ring_retire(ce->ring);
    }
    
    int __intel_context_do_pin_ww(struct intel_context *ce,
    			      struct i915_gem_ww_ctx *ww)
    {
    	bool handoff = false;
    	void *vaddr;
    	int err = 0;
    
    	if (unlikely(!test_bit(CONTEXT_ALLOC_BIT, &ce->flags))) {
    		err = intel_context_alloc_state(ce);
    		if (err)
    			return err;
    	}
    
    	/*
    	 * We always pin the context/ring/timeline here, to ensure a pin
    	 * refcount for __intel_context_active(), which prevent a lock
    	 * inversion of ce->pin_mutex vs dma_resv_lock().
    	 */
    
    	err = i915_gem_object_lock(ce->timeline->hwsp_ggtt->obj, ww);
    	if (!err && ce->ring->vma->obj)
    		err = i915_gem_object_lock(ce->ring->vma->obj, ww);
    	if (!err && ce->state)
    		err = i915_gem_object_lock(ce->state->obj, ww);
    	if (!err)
    		err = intel_context_pre_pin(ce, ww);
    	if (err)
    		return err;
    
    	err = i915_active_acquire(&ce->active);
    	if (err)
    		goto err_ctx_unpin;
    
    	err = ce->ops->pre_pin(ce, ww, &vaddr);
    	if (err)
    		goto err_release;
    
    	err = mutex_lock_interruptible(&ce->pin_mutex);
    	if (err)
    		goto err_post_unpin;
    
    	if (unlikely(intel_context_is_closed(ce))) {
    		err = -ENOENT;
    		goto err_unlock;
    	}
    
    	if (likely(!atomic_add_unless(&ce->pin_count, 1, 0))) {
    		err = intel_context_active_acquire(ce);
    		if (unlikely(err))
    			goto err_unlock;
    
    		err = ce->ops->pin(ce, vaddr);
    		if (err) {
    			intel_context_active_release(ce);
    			goto err_unlock;
    		}
    
    		CE_TRACE(ce, "pin ring:{start:%08x, head:%04x, tail:%04x}\n",
    			 i915_ggtt_offset(ce->ring->vma),
    			 ce->ring->head, ce->ring->tail);
    
    		handoff = true;
    		smp_mb__before_atomic(); /* flush pin before it is visible */
    		atomic_inc(&ce->pin_count);
    	}
    
    	GEM_BUG_ON(!intel_context_is_pinned(ce)); /* no overflow! */
    
    err_unlock:
    	mutex_unlock(&ce->pin_mutex);
    err_post_unpin:
    	if (!handoff)
    		ce->ops->post_unpin(ce);
    err_release:
    	i915_active_release(&ce->active);
    err_ctx_unpin:
    	intel_context_post_unpin(ce);
    
    	/*
    	 * Unlock the hwsp_ggtt object since it's shared.
    	 * In principle we can unlock all the global state locked above
    	 * since it's pinned and doesn't need fencing, and will
    	 * thus remain resident until it is explicitly unpinned.
    	 */
    	i915_gem_ww_unlock_single(ce->timeline->hwsp_ggtt->obj);
    
    	return err;
    }
    
    int __intel_context_do_pin(struct intel_context *ce)
    {
    	struct i915_gem_ww_ctx ww;
    	int err;
    
    	i915_gem_ww_ctx_init(&ww, true);
    retry:
    	err = __intel_context_do_pin_ww(ce, &ww);
    	if (err == -EDEADLK) {
    		err = i915_gem_ww_ctx_backoff(&ww);
    		if (!err)
    			goto retry;
    	}
    	i915_gem_ww_ctx_fini(&ww);
    	return err;
    }
    
    void intel_context_unpin(struct intel_context *ce)
    {
    	if (!atomic_dec_and_test(&ce->pin_count))
    		return;
    
    	CE_TRACE(ce, "unpin\n");
    	ce->ops->unpin(ce);
    	ce->ops->post_unpin(ce);
    
    	/*
    	 * Once released, we may asynchronously drop the active reference.
    	 * As that may be the only reference keeping the context alive,
    	 * take an extra now so that it is not freed before we finish
    	 * dereferencing it.
    	 */
    	intel_context_get(ce);
    	intel_context_active_release(ce);
    	intel_context_put(ce);
    }
    
    __i915_active_call
    static void __intel_context_retire(struct i915_active *active)
    {
    	struct intel_context *ce = container_of(active, typeof(*ce), active);
    
    	CE_TRACE(ce, "retire runtime: { total:%lluns, avg:%lluns }\n",
    		 intel_context_get_total_runtime_ns(ce),
    		 intel_context_get_avg_runtime_ns(ce));
    
    	set_bit(CONTEXT_VALID_BIT, &ce->flags);
    	intel_context_post_unpin(ce);
    	intel_context_put(ce);
    }
    
    static int __intel_context_active(struct i915_active *active)
    {
    	struct intel_context *ce = container_of(active, typeof(*ce), active);
    
    	intel_context_get(ce);
    
    	/* everything should already be activated by intel_context_pre_pin() */
    	GEM_WARN_ON(!i915_active_acquire_if_busy(&ce->ring->vma->active));
    	__intel_ring_pin(ce->ring);
    
    	__intel_timeline_pin(ce->timeline);
    
    	if (ce->state) {
    		GEM_WARN_ON(!i915_active_acquire_if_busy(&ce->state->active));
    		__i915_vma_pin(ce->state);
    		i915_vma_make_unshrinkable(ce->state);
    	}
    
    	return 0;
    }
    
    void
    intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine)
    {
    	GEM_BUG_ON(!engine->cops);
    	GEM_BUG_ON(!engine->gt->vm);
    
    	kref_init(&ce->ref);
    
    	ce->engine = engine;
    	ce->ops = engine->cops;
    	ce->sseu = engine->sseu;
    	ce->ring = __intel_context_ring_size(SZ_4K);
    
    	ewma_runtime_init(&ce->runtime.avg);
    
    	ce->vm = i915_vm_get(engine->gt->vm);
    
    	/* NB ce->signal_link/lock is used under RCU */
    	spin_lock_init(&ce->signal_lock);
    	INIT_LIST_HEAD(&ce->signals);
    
    	mutex_init(&ce->pin_mutex);
    
    	i915_active_init(&ce->active,
    			 __intel_context_active, __intel_context_retire);
    }
    
    void intel_context_fini(struct intel_context *ce)
    {
    	if (ce->timeline)
    		intel_timeline_put(ce->timeline);
    	i915_vm_put(ce->vm);
    
    	mutex_destroy(&ce->pin_mutex);
    	i915_active_fini(&ce->active);
    }
    
    static void i915_global_context_shrink(void)
    {
    	kmem_cache_shrink(global.slab_ce);
    }
    
    static void i915_global_context_exit(void)
    {
    	kmem_cache_destroy(global.slab_ce);
    }
    
    static struct i915_global_context global = { {
    	.shrink = i915_global_context_shrink,
    	.exit = i915_global_context_exit,
    } };
    
    int __init i915_global_context_init(void)
    {
    	global.slab_ce = KMEM_CACHE(intel_context, SLAB_HWCACHE_ALIGN);
    	if (!global.slab_ce)
    		return -ENOMEM;
    
    	i915_global_register(&global.base);
    	return 0;
    }
    
    void intel_context_enter_engine(struct intel_context *ce)
    {
    	intel_engine_pm_get(ce->engine);
    	intel_timeline_enter(ce->timeline);
    }
    
    void intel_context_exit_engine(struct intel_context *ce)
    {
    	intel_timeline_exit(ce->timeline);
    	intel_engine_pm_put(ce->engine);
    }
    
    int intel_context_prepare_remote_request(struct intel_context *ce,
    					 struct i915_request *rq)
    {
    	struct intel_timeline *tl = ce->timeline;
    	int err;
    
    	/* Only suitable for use in remotely modifying this context */
    	GEM_BUG_ON(rq->context == ce);
    
    	if (rcu_access_pointer(rq->timeline) != tl) { /* timeline sharing! */
    		/* Queue this switch after current activity by this context. */
    		err = i915_active_fence_set(&tl->last_request, rq);
    		if (err)
    			return err;
    	}
    
    	/*
    	 * Guarantee context image and the timeline remains pinned until the
    	 * modifying request is retired by setting the ce activity tracker.
    	 *
    	 * But we only need to take one pin on the account of it. Or in other
    	 * words transfer the pinned ce object to tracked active request.
    	 */
    	GEM_BUG_ON(i915_active_is_idle(&ce->active));
    	return i915_active_add_request(&ce->active, rq);
    }
    
    struct i915_request *intel_context_create_request(struct intel_context *ce)
    {
    	struct i915_gem_ww_ctx ww;
    	struct i915_request *rq;
    	int err;
    
    	i915_gem_ww_ctx_init(&ww, true);
    retry:
    	err = intel_context_pin_ww(ce, &ww);
    	if (!err) {
    		rq = i915_request_create(ce);
    		intel_context_unpin(ce);
    	} else if (err == -EDEADLK) {
    		err = i915_gem_ww_ctx_backoff(&ww);
    		if (!err)
    			goto retry;
    		rq = ERR_PTR(err);
    	} else {
    		rq = ERR_PTR(err);
    	}
    
    	i915_gem_ww_ctx_fini(&ww);
    
    	if (IS_ERR(rq))
    		return rq;
    
    	/*
    	 * timeline->mutex should be the inner lock, but is used as outer lock.
    	 * Hack around this to shut up lockdep in selftests..
    	 */
    	lockdep_unpin_lock(&ce->timeline->mutex, rq->cookie);
    	mutex_release(&ce->timeline->mutex.dep_map, _RET_IP_);
    	mutex_acquire(&ce->timeline->mutex.dep_map, SINGLE_DEPTH_NESTING, 0, _RET_IP_);
    	rq->cookie = lockdep_pin_lock(&ce->timeline->mutex);
    
    	return rq;
    }
    
    #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
    #include "selftest_context.c"
    #endif