// 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_trace.h"

#include "intel_context.h"
#include "intel_engine.h"
#include "intel_engine_pm.h"
#include "intel_ring.h"

static struct kmem_cache *slab_ce;

static struct intel_context *intel_context_alloc(void)
{
        return kmem_cache_zalloc(slab_ce, GFP_KERNEL);
}

static void rcu_context_free(struct rcu_head *rcu)
{
        struct intel_context *ce = container_of(rcu, typeof(*ce), rcu);

        trace_intel_context_free(ce);
        kmem_cache_free(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);
        trace_intel_context_create(ce);
        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) || intel_engine_uses_guc(ce->engine))
                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! */

        trace_intel_context_do_pin(ce);

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_do_unpin(struct intel_context *ce, int sub)
{
        if (!atomic_sub_and_test(sub, &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);
        trace_intel_context_do_unpin(ce);
        intel_context_put(ce);
}

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;
}

static int __i915_sw_fence_call
sw_fence_dummy_notify(struct i915_sw_fence *sf,
                      enum i915_sw_fence_notify state)
{
        return NOTIFY_DONE;
}

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 = NULL;
        ce->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);

        spin_lock_init(&ce->guc_state.lock);
        INIT_LIST_HEAD(&ce->guc_state.fences);

        spin_lock_init(&ce->guc_active.lock);
        INIT_LIST_HEAD(&ce->guc_active.requests);

        ce->guc_id = GUC_INVALID_LRC_ID;
        INIT_LIST_HEAD(&ce->guc_id_link);

        /*
         * Initialize fence to be complete as this is expected to be complete
         * unless there is a pending schedule disable outstanding.
         */
        i915_sw_fence_init(&ce->guc_blocked, sw_fence_dummy_notify);
        i915_sw_fence_commit(&ce->guc_blocked);

        i915_active_init(&ce->active,
                         __intel_context_active, __intel_context_retire, 0);
}

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);
        i915_sw_fence_fini(&ce->guc_blocked);
}

void i915_context_module_exit(void)
{
        kmem_cache_destroy(slab_ce);
}

int __init i915_context_module_init(void)
{
        slab_ce = KMEM_CACHE(intel_context, SLAB_HWCACHE_ALIGN);
        if (!slab_ce)
                return -ENOMEM;

        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;
}

struct i915_request *intel_context_find_active_request(struct intel_context *ce)
{
        struct i915_request *rq, *active = NULL;
        unsigned long flags;

        GEM_BUG_ON(!intel_engine_uses_guc(ce->engine));

        spin_lock_irqsave(&ce->guc_active.lock, flags);
        list_for_each_entry_reverse(rq, &ce->guc_active.requests,
                                    sched.link) {
                if (i915_request_completed(rq))
                        break;

                active = rq;
        }
        spin_unlock_irqrestore(&ce->guc_active.lock, flags);

        return active;
}

#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
#include "selftest_context.c"
#endif