/*
 * Copyright © 2016 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 */

#include <linux/sched/mm.h>
#include <drm/drm_gem.h>

#include "display/intel_frontbuffer.h"

#include "gt/intel_engine.h"
#include "gt/intel_engine_heartbeat.h"
#include "gt/intel_gt.h"
#include "gt/intel_gt_requests.h"

#include "i915_drv.h"
#include "i915_globals.h"
#include "i915_sw_fence_work.h"
#include "i915_trace.h"
#include "i915_vma.h"

static struct i915_global_vma {
        struct i915_global base;
        struct kmem_cache *slab_vmas;
} global;

struct i915_vma *i915_vma_alloc(void)
{
        return kmem_cache_zalloc(global.slab_vmas, GFP_KERNEL);
}

void i915_vma_free(struct i915_vma *vma)
{
        return kmem_cache_free(global.slab_vmas, vma);
}

#if IS_ENABLED(CONFIG_DRM_I915_ERRLOG_GEM) && IS_ENABLED(CONFIG_DRM_DEBUG_MM)

#include <linux/stackdepot.h>

static void vma_print_allocator(struct i915_vma *vma, const char *reason)
{
        unsigned long *entries;
        unsigned int nr_entries;
        char buf[512];

        if (!vma->node.stack) {
                DRM_DEBUG_DRIVER("vma.node [%08llx + %08llx] %s: unknown owner\n",
                                 vma->node.start, vma->node.size, reason);
                return;
        }

        nr_entries = stack_depot_fetch(vma->node.stack, &entries);
        stack_trace_snprint(buf, sizeof(buf), entries, nr_entries, 0);
        DRM_DEBUG_DRIVER("vma.node [%08llx + %08llx] %s: inserted at %s\n",
                         vma->node.start, vma->node.size, reason, buf);
}

#else

static void vma_print_allocator(struct i915_vma *vma, const char *reason)
{
}

#endif

static inline struct i915_vma *active_to_vma(struct i915_active *ref)
{
        return container_of(ref, typeof(struct i915_vma), active);
}

static int __i915_vma_active(struct i915_active *ref)
{
        return i915_vma_tryget(active_to_vma(ref)) ? 0 : -ENOENT;
}

__i915_active_call
static void __i915_vma_retire(struct i915_active *ref)
{
        i915_vma_put(active_to_vma(ref));
}

static struct i915_vma *
vma_create(struct drm_i915_gem_object *obj,
           struct i915_address_space *vm,
           const struct i915_ggtt_view *view)
{
        struct i915_vma *vma;
        struct rb_node *rb, **p;

        /* The aliasing_ppgtt should never be used directly! */
        GEM_BUG_ON(vm == &vm->gt->ggtt->alias->vm);

        vma = i915_vma_alloc();
        if (vma == NULL)
                return ERR_PTR(-ENOMEM);

        kref_init(&vma->ref);
        mutex_init(&vma->pages_mutex);
        vma->vm = i915_vm_get(vm);
        vma->ops = &vm->vma_ops;
        vma->obj = obj;
        vma->resv = obj->base.resv;
        vma->size = obj->base.size;
        vma->display_alignment = I915_GTT_MIN_ALIGNMENT;

        i915_active_init(&vma->active, __i915_vma_active, __i915_vma_retire);

        /* Declare ourselves safe for use inside shrinkers */
        if (IS_ENABLED(CONFIG_LOCKDEP)) {
                fs_reclaim_acquire(GFP_KERNEL);
                might_lock(&vma->active.mutex);
                fs_reclaim_release(GFP_KERNEL);
        }

        INIT_LIST_HEAD(&vma->closed_link);

        if (view && view->type != I915_GGTT_VIEW_NORMAL) {
                vma->ggtt_view = *view;
                if (view->type == I915_GGTT_VIEW_PARTIAL) {
                        GEM_BUG_ON(range_overflows_t(u64,
                                                     view->partial.offset,
                                                     view->partial.size,
                                                     obj->base.size >> PAGE_SHIFT));
                        vma->size = view->partial.size;
                        vma->size <<= PAGE_SHIFT;
                        GEM_BUG_ON(vma->size > obj->base.size);
                } else if (view->type == I915_GGTT_VIEW_ROTATED) {
                        vma->size = intel_rotation_info_size(&view->rotated);
                        vma->size <<= PAGE_SHIFT;
                } else if (view->type == I915_GGTT_VIEW_REMAPPED) {
                        vma->size = intel_remapped_info_size(&view->remapped);
                        vma->size <<= PAGE_SHIFT;
                }
        }

        if (unlikely(vma->size > vm->total))
                goto err_vma;

        GEM_BUG_ON(!IS_ALIGNED(vma->size, I915_GTT_PAGE_SIZE));

        if (i915_is_ggtt(vm)) {
                if (unlikely(overflows_type(vma->size, u32)))
                        goto err_vma;

                vma->fence_size = i915_gem_fence_size(vm->i915, vma->size,
                                                      i915_gem_object_get_tiling(obj),
                                                      i915_gem_object_get_stride(obj));
                if (unlikely(vma->fence_size < vma->size || /* overflow */
                             vma->fence_size > vm->total))
                        goto err_vma;

                GEM_BUG_ON(!IS_ALIGNED(vma->fence_size, I915_GTT_MIN_ALIGNMENT));

                vma->fence_alignment = i915_gem_fence_alignment(vm->i915, vma->size,
                                                                i915_gem_object_get_tiling(obj),
                                                                i915_gem_object_get_stride(obj));
                GEM_BUG_ON(!is_power_of_2(vma->fence_alignment));

                __set_bit(I915_VMA_GGTT_BIT, __i915_vma_flags(vma));
        }

        spin_lock(&obj->vma.lock);

        rb = NULL;
        p = &obj->vma.tree.rb_node;
        while (*p) {
                struct i915_vma *pos;
                long cmp;

                rb = *p;
                pos = rb_entry(rb, struct i915_vma, obj_node);

                /*
                 * If the view already exists in the tree, another thread
                 * already created a matching vma, so return the older instance
                 * and dispose of ours.
                 */
                cmp = i915_vma_compare(pos, vm, view);
                if (cmp == 0) {
                        spin_unlock(&obj->vma.lock);
                        i915_vma_free(vma);
                        return pos;
                }

                if (cmp < 0)
                        p = &rb->rb_right;
                else
                        p = &rb->rb_left;
        }
        rb_link_node(&vma->obj_node, rb, p);
        rb_insert_color(&vma->obj_node, &obj->vma.tree);

        if (i915_vma_is_ggtt(vma))
                /*
                 * We put the GGTT vma at the start of the vma-list, followed
                 * by the ppGGTT vma. This allows us to break early when
                 * iterating over only the GGTT vma for an object, see
                 * for_each_ggtt_vma()
                 */
                list_add(&vma->obj_link, &obj->vma.list);
        else
                list_add_tail(&vma->obj_link, &obj->vma.list);

        spin_unlock(&obj->vma.lock);

        return vma;

err_vma:
        i915_vma_free(vma);
        return ERR_PTR(-E2BIG);
}

static struct i915_vma *
vma_lookup(struct drm_i915_gem_object *obj,
           struct i915_address_space *vm,
           const struct i915_ggtt_view *view)
{
        struct rb_node *rb;

        rb = obj->vma.tree.rb_node;
        while (rb) {
                struct i915_vma *vma = rb_entry(rb, struct i915_vma, obj_node);
                long cmp;

                cmp = i915_vma_compare(vma, vm, view);
                if (cmp == 0)
                        return vma;

                if (cmp < 0)
                        rb = rb->rb_right;
                else
                        rb = rb->rb_left;
        }

        return NULL;
}

/**
 * i915_vma_instance - return the singleton instance of the VMA
 * @obj: parent &struct drm_i915_gem_object to be mapped
 * @vm: address space in which the mapping is located
 * @view: additional mapping requirements
 *
 * i915_vma_instance() looks up an existing VMA of the @obj in the @vm with
 * the same @view characteristics. If a match is not found, one is created.
 * Once created, the VMA is kept until either the object is freed, or the
 * address space is closed.
 *
 * Returns the vma, or an error pointer.
 */
struct i915_vma *
i915_vma_instance(struct drm_i915_gem_object *obj,
                  struct i915_address_space *vm,
                  const struct i915_ggtt_view *view)
{
        struct i915_vma *vma;

        GEM_BUG_ON(view && !i915_is_ggtt(vm));
        GEM_BUG_ON(!atomic_read(&vm->open));

        spin_lock(&obj->vma.lock);
        vma = vma_lookup(obj, vm, view);
        spin_unlock(&obj->vma.lock);

        /* vma_create() will resolve the race if another creates the vma */
        if (unlikely(!vma))
                vma = vma_create(obj, vm, view);

        GEM_BUG_ON(!IS_ERR(vma) && i915_vma_compare(vma, vm, view));
        return vma;
}

struct i915_vma_work {
        struct dma_fence_work base;
        struct i915_vma *vma;
        struct drm_i915_gem_object *pinned;
        enum i915_cache_level cache_level;
        unsigned int flags;
};

static int __vma_bind(struct dma_fence_work *work)
{
        struct i915_vma_work *vw = container_of(work, typeof(*vw), base);
        struct i915_vma *vma = vw->vma;
        int err;

        err = vma->ops->bind_vma(vma, vw->cache_level, vw->flags);
        if (err)
                atomic_or(I915_VMA_ERROR, &vma->flags);

        return err;
}

static void __vma_release(struct dma_fence_work *work)
{
        struct i915_vma_work *vw = container_of(work, typeof(*vw), base);

        if (vw->pinned)
                __i915_gem_object_unpin_pages(vw->pinned);
}

static const struct dma_fence_work_ops bind_ops = {
        .name = "bind",
        .work = __vma_bind,
        .release = __vma_release,
};

struct i915_vma_work *i915_vma_work(void)
{
        struct i915_vma_work *vw;

        vw = kzalloc(sizeof(*vw), GFP_KERNEL);
        if (!vw)
                return NULL;

        dma_fence_work_init(&vw->base, &bind_ops);
        vw->base.dma.error = -EAGAIN; /* disable the worker by default */

        return vw;
}

/**
 * i915_vma_bind - Sets up PTEs for an VMA in it's corresponding address space.
 * @vma: VMA to map
 * @cache_level: mapping cache level
 * @flags: flags like global or local mapping
 * @work: preallocated worker for allocating and binding the PTE
 *
 * DMA addresses are taken from the scatter-gather table of this object (or of
 * this VMA in case of non-default GGTT views) and PTE entries set up.
 * Note that DMA addresses are also the only part of the SG table we care about.
 */
int i915_vma_bind(struct i915_vma *vma,
                  enum i915_cache_level cache_level,
                  u32 flags,
                  struct i915_vma_work *work)
{
        u32 bind_flags;
        u32 vma_flags;
        int ret;

        GEM_BUG_ON(!drm_mm_node_allocated(&vma->node));
        GEM_BUG_ON(vma->size > vma->node.size);

        if (GEM_DEBUG_WARN_ON(range_overflows(vma->node.start,
                                              vma->node.size,
                                              vma->vm->total)))
                return -ENODEV;

        if (GEM_DEBUG_WARN_ON(!flags))
                return -EINVAL;

        bind_flags = flags;
        bind_flags &= I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND;

        vma_flags = atomic_read(&vma->flags);
        vma_flags &= I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND;
        if (flags & PIN_UPDATE)
                bind_flags |= vma_flags;
        else
                bind_flags &= ~vma_flags;
        if (bind_flags == 0)
                return 0;

        GEM_BUG_ON(!vma->pages);

        trace_i915_vma_bind(vma, bind_flags);
        if (work && (bind_flags & ~vma_flags) & vma->vm->bind_async_flags) {
                work->vma = vma;
                work->cache_level = cache_level;
                work->flags = bind_flags | I915_VMA_ALLOC;

                /*
                 * Note we only want to chain up to the migration fence on
                 * the pages (not the object itself). As we don't track that,
                 * yet, we have to use the exclusive fence instead.
                 *
                 * Also note that we do not want to track the async vma as
                 * part of the obj->resv->excl_fence as it only affects
                 * execution and not content or object's backing store lifetime.
                 */
                GEM_BUG_ON(i915_active_has_exclusive(&vma->active));
                i915_active_set_exclusive(&vma->active, &work->base.dma);
                work->base.dma.error = 0; /* enable the queue_work() */

                if (vma->obj) {
                        __i915_gem_object_pin_pages(vma->obj);
                        work->pinned = vma->obj;
                }
        } else {
                GEM_BUG_ON((bind_flags & ~vma_flags) & vma->vm->bind_async_flags);
                ret = vma->ops->bind_vma(vma, cache_level, bind_flags);
                if (ret)
                        return ret;
        }

        atomic_or(bind_flags, &vma->flags);
        return 0;
}

void __iomem *i915_vma_pin_iomap(struct i915_vma *vma)
{
        void __iomem *ptr;
        int err;

        if (GEM_WARN_ON(!i915_vma_is_map_and_fenceable(vma))) {
                err = -ENODEV;
                goto err;
        }

        GEM_BUG_ON(!i915_vma_is_ggtt(vma));
        GEM_BUG_ON(!i915_vma_is_bound(vma, I915_VMA_GLOBAL_BIND));

        ptr = READ_ONCE(vma->iomap);
        if (ptr == NULL) {
                ptr = io_mapping_map_wc(&i915_vm_to_ggtt(vma->vm)->iomap,
                                        vma->node.start,
                                        vma->node.size);
                if (ptr == NULL) {
                        err = -ENOMEM;
                        goto err;
                }

                if (unlikely(cmpxchg(&vma->iomap, NULL, ptr))) {
                        io_mapping_unmap(ptr);
                        ptr = vma->iomap;
                }
        }

        __i915_vma_pin(vma);

        err = i915_vma_pin_fence(vma);
        if (err)
                goto err_unpin;

        i915_vma_set_ggtt_write(vma);

        /* NB Access through the GTT requires the device to be awake. */
        return ptr;

err_unpin:
        __i915_vma_unpin(vma);
err:
        return IO_ERR_PTR(err);
}

void i915_vma_flush_writes(struct i915_vma *vma)
{
        if (i915_vma_unset_ggtt_write(vma))
                intel_gt_flush_ggtt_writes(vma->vm->gt);
}

void i915_vma_unpin_iomap(struct i915_vma *vma)
{
        GEM_BUG_ON(vma->iomap == NULL);

        i915_vma_flush_writes(vma);

        i915_vma_unpin_fence(vma);
        i915_vma_unpin(vma);
}

void i915_vma_unpin_and_release(struct i915_vma **p_vma, unsigned int flags)
{
        struct i915_vma *vma;
        struct drm_i915_gem_object *obj;

        vma = fetch_and_zero(p_vma);
        if (!vma)
                return;

        obj = vma->obj;
        GEM_BUG_ON(!obj);

        i915_vma_unpin(vma);
        i915_vma_close(vma);

        if (flags & I915_VMA_RELEASE_MAP)
                i915_gem_object_unpin_map(obj);

        i915_gem_object_put(obj);
}

bool i915_vma_misplaced(const struct i915_vma *vma,
                        u64 size, u64 alignment, u64 flags)
{
        if (!drm_mm_node_allocated(&vma->node))
                return false;

        if (test_bit(I915_VMA_ERROR_BIT, __i915_vma_flags(vma)))
                return true;

        if (vma->node.size < size)
                return true;

        GEM_BUG_ON(alignment && !is_power_of_2(alignment));
        if (alignment && !IS_ALIGNED(vma->node.start, alignment))
                return true;

        if (flags & PIN_MAPPABLE && !i915_vma_is_map_and_fenceable(vma))
                return true;

        if (flags & PIN_OFFSET_BIAS &&
            vma->node.start < (flags & PIN_OFFSET_MASK))
                return true;

        if (flags & PIN_OFFSET_FIXED &&
            vma->node.start != (flags & PIN_OFFSET_MASK))
                return true;

        return false;
}

void __i915_vma_set_map_and_fenceable(struct i915_vma *vma)
{
        bool mappable, fenceable;

        GEM_BUG_ON(!i915_vma_is_ggtt(vma));
        GEM_BUG_ON(!vma->fence_size);

        fenceable = (vma->node.size >= vma->fence_size &&
                     IS_ALIGNED(vma->node.start, vma->fence_alignment));

        mappable = vma->node.start + vma->fence_size <= i915_vm_to_ggtt(vma->vm)->mappable_end;

        if (mappable && fenceable)
                set_bit(I915_VMA_CAN_FENCE_BIT, __i915_vma_flags(vma));
        else
                clear_bit(I915_VMA_CAN_FENCE_BIT, __i915_vma_flags(vma));
}

bool i915_gem_valid_gtt_space(struct i915_vma *vma, unsigned long color)
{
        struct drm_mm_node *node = &vma->node;
        struct drm_mm_node *other;

        /*
         * On some machines we have to be careful when putting differing types
         * of snoopable memory together to avoid the prefetcher crossing memory
         * domains and dying. During vm initialisation, we decide whether or not
         * these constraints apply and set the drm_mm.color_adjust
         * appropriately.
         */
        if (!i915_vm_has_cache_coloring(vma->vm))
                return true;

        /* Only valid to be called on an already inserted vma */
        GEM_BUG_ON(!drm_mm_node_allocated(node));
        GEM_BUG_ON(list_empty(&node->node_list));

        other = list_prev_entry(node, node_list);
        if (i915_node_color_differs(other, color) &&
            !drm_mm_hole_follows(other))
                return false;

        other = list_next_entry(node, node_list);
        if (i915_node_color_differs(other, color) &&
            !drm_mm_hole_follows(node))
                return false;

        return true;
}

static void assert_bind_count(const struct drm_i915_gem_object *obj)
{
        /*
         * Combine the assertion that the object is bound and that we have
         * pinned its pages. But we should never have bound the object
         * more than we have pinned its pages. (For complete accuracy, we
         * assume that no else is pinning the pages, but as a rough assertion
         * that we will not run into problems later, this will do!)
         */
        GEM_BUG_ON(atomic_read(&obj->mm.pages_pin_count) < atomic_read(&obj->bind_count));
}

/**
 * i915_vma_insert - finds a slot for the vma in its address space
 * @vma: the vma
 * @size: requested size in bytes (can be larger than the VMA)
 * @alignment: required alignment
 * @flags: mask of PIN_* flags to use
 *
 * First we try to allocate some free space that meets the requirements for
 * the VMA. Failiing that, if the flags permit, it will evict an old VMA,
 * preferrably the oldest idle entry to make room for the new VMA.
 *
 * Returns:
 * 0 on success, negative error code otherwise.
 */
static int
i915_vma_insert(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
{
        unsigned long color;
        u64 start, end;
        int ret;

        GEM_BUG_ON(i915_vma_is_closed(vma));
        GEM_BUG_ON(i915_vma_is_bound(vma, I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND));
        GEM_BUG_ON(drm_mm_node_allocated(&vma->node));

        size = max(size, vma->size);
        alignment = max(alignment, vma->display_alignment);
        if (flags & PIN_MAPPABLE) {
                size = max_t(typeof(size), size, vma->fence_size);
                alignment = max_t(typeof(alignment),
                                  alignment, vma->fence_alignment);
        }

        GEM_BUG_ON(!IS_ALIGNED(size, I915_GTT_PAGE_SIZE));
        GEM_BUG_ON(!IS_ALIGNED(alignment, I915_GTT_MIN_ALIGNMENT));
        GEM_BUG_ON(!is_power_of_2(alignment));

        start = flags & PIN_OFFSET_BIAS ? flags & PIN_OFFSET_MASK : 0;
        GEM_BUG_ON(!IS_ALIGNED(start, I915_GTT_PAGE_SIZE));

        end = vma->vm->total;
        if (flags & PIN_MAPPABLE)
                end = min_t(u64, end, i915_vm_to_ggtt(vma->vm)->mappable_end);
        if (flags & PIN_ZONE_4G)
                end = min_t(u64, end, (1ULL << 32) - I915_GTT_PAGE_SIZE);
        GEM_BUG_ON(!IS_ALIGNED(end, I915_GTT_PAGE_SIZE));

        /* If binding the object/GGTT view requires more space than the entire
         * aperture has, reject it early before evicting everything in a vain
         * attempt to find space.
         */
        if (size > end) {
                DRM_DEBUG("Attempting to bind an object larger than the aperture: request=%llu > %s aperture=%llu\n",
                          size, flags & PIN_MAPPABLE ? "mappable" : "total",
                          end);
                return -ENOSPC;
        }

        color = 0;
        if (vma->obj && i915_vm_has_cache_coloring(vma->vm))
                color = vma->obj->cache_level;

        if (flags & PIN_OFFSET_FIXED) {
                u64 offset = flags & PIN_OFFSET_MASK;
                if (!IS_ALIGNED(offset, alignment) ||
                    range_overflows(offset, size, end))
                        return -EINVAL;

                ret = i915_gem_gtt_reserve(vma->vm, &vma->node,
                                           size, offset, color,
                                           flags);
                if (ret)
                        return ret;
        } else {
                /*
                 * We only support huge gtt pages through the 48b PPGTT,
                 * however we also don't want to force any alignment for
                 * objects which need to be tightly packed into the low 32bits.
                 *
                 * Note that we assume that GGTT are limited to 4GiB for the
                 * forseeable future. See also i915_ggtt_offset().
                 */
                if (upper_32_bits(end - 1) &&
                    vma->page_sizes.sg > I915_GTT_PAGE_SIZE) {
                        /*
                         * We can't mix 64K and 4K PTEs in the same page-table
                         * (2M block), and so to avoid the ugliness and
                         * complexity of coloring we opt for just aligning 64K
                         * objects to 2M.
                         */
                        u64 page_alignment =
                                rounddown_pow_of_two(vma->page_sizes.sg |
                                                     I915_GTT_PAGE_SIZE_2M);

                        /*
                         * Check we don't expand for the limited Global GTT
                         * (mappable aperture is even more precious!). This
                         * also checks that we exclude the aliasing-ppgtt.
                         */
                        GEM_BUG_ON(i915_vma_is_ggtt(vma));

                        alignment = max(alignment, page_alignment);

                        if (vma->page_sizes.sg & I915_GTT_PAGE_SIZE_64K)
                                size = round_up(size, I915_GTT_PAGE_SIZE_2M);
                }

                ret = i915_gem_gtt_insert(vma->vm, &vma->node,
                                          size, alignment, color,
                                          start, end, flags);
                if (ret)
                        return ret;

                GEM_BUG_ON(vma->node.start < start);
                GEM_BUG_ON(vma->node.start + vma->node.size > end);
        }
        GEM_BUG_ON(!drm_mm_node_allocated(&vma->node));
        GEM_BUG_ON(!i915_gem_valid_gtt_space(vma, color));

        if (vma->obj) {
                struct drm_i915_gem_object *obj = vma->obj;

                atomic_inc(&obj->bind_count);
                assert_bind_count(obj);
        }
        list_add_tail(&vma->vm_link, &vma->vm->bound_list);

        return 0;
}

static void
i915_vma_detach(struct i915_vma *vma)
{
        GEM_BUG_ON(!drm_mm_node_allocated(&vma->node));
        GEM_BUG_ON(i915_vma_is_bound(vma, I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND));

        /*
         * And finally now the object is completely decoupled from this
         * vma, we can drop its hold on the backing storage and allow
         * it to be reaped by the shrinker.
         */
        list_del(&vma->vm_link);
        if (vma->obj) {
                struct drm_i915_gem_object *obj = vma->obj;

                assert_bind_count(obj);
                atomic_dec(&obj->bind_count);
        }
}

static bool try_qad_pin(struct i915_vma *vma, unsigned int flags)
{
        unsigned int bound;
        bool pinned = true;

        bound = atomic_read(&vma->flags);
        do {
                if (unlikely(flags & ~bound))
                        return false;

                if (unlikely(bound & (I915_VMA_OVERFLOW | I915_VMA_ERROR)))
                        return false;

                if (!(bound & I915_VMA_PIN_MASK))
                        goto unpinned;

                GEM_BUG_ON(((bound + 1) & I915_VMA_PIN_MASK) == 0);
        } while (!atomic_try_cmpxchg(&vma->flags, &bound, bound + 1));

        return true;

unpinned:
        /*
         * If pin_count==0, but we are bound, check under the lock to avoid
         * racing with a concurrent i915_vma_unbind().
         */
        mutex_lock(&vma->vm->mutex);
        do {
                if (unlikely(bound & (I915_VMA_OVERFLOW | I915_VMA_ERROR))) {
                        pinned = false;
                        break;
                }

                if (unlikely(flags & ~bound)) {
                        pinned = false;
                        break;
                }
        } while (!atomic_try_cmpxchg(&vma->flags, &bound, bound + 1));
        mutex_unlock(&vma->vm->mutex);

        return pinned;
}

static int vma_get_pages(struct i915_vma *vma)
{
        int err = 0;

        if (atomic_add_unless(&vma->pages_count, 1, 0))
                return 0;

        /* Allocations ahoy! */
        if (mutex_lock_interruptible(&vma->pages_mutex))
                return -EINTR;

        if (!atomic_read(&vma->pages_count)) {
                if (vma->obj) {
                        err = i915_gem_object_pin_pages(vma->obj);
                        if (err)
                                goto unlock;
                }

                err = vma->ops->set_pages(vma);
                if (err) {
                        if (vma->obj)
                                i915_gem_object_unpin_pages(vma->obj);
                        goto unlock;
                }
        }
        atomic_inc(&vma->pages_count);

unlock:
        mutex_unlock(&vma->pages_mutex);

        return err;
}

static void __vma_put_pages(struct i915_vma *vma, unsigned int count)
{
        /* We allocate under vma_get_pages, so beware the shrinker */
        mutex_lock_nested(&vma->pages_mutex, SINGLE_DEPTH_NESTING);
        GEM_BUG_ON(atomic_read(&vma->pages_count) < count);
        if (atomic_sub_return(count, &vma->pages_count) == 0) {
                vma->ops->clear_pages(vma);
                GEM_BUG_ON(vma->pages);
                if (vma->obj)
                        i915_gem_object_unpin_pages(vma->obj);
        }
        mutex_unlock(&vma->pages_mutex);
}

static void vma_put_pages(struct i915_vma *vma)
{
        if (atomic_add_unless(&vma->pages_count, -1, 1))
                return;

        __vma_put_pages(vma, 1);
}

static void vma_unbind_pages(struct i915_vma *vma)
{
        unsigned int count;

        lockdep_assert_held(&vma->vm->mutex);

        /* The upper portion of pages_count is the number of bindings */
        count = atomic_read(&vma->pages_count);
        count >>= I915_VMA_PAGES_BIAS;
        GEM_BUG_ON(!count);

        __vma_put_pages(vma, count | count << I915_VMA_PAGES_BIAS);
}

int i915_vma_pin(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
{
        struct i915_vma_work *work = NULL;
        intel_wakeref_t wakeref = 0;
        unsigned int bound;
        int err;

        BUILD_BUG_ON(PIN_GLOBAL != I915_VMA_GLOBAL_BIND);
        BUILD_BUG_ON(PIN_USER != I915_VMA_LOCAL_BIND);

        GEM_BUG_ON(flags & PIN_UPDATE);
        GEM_BUG_ON(!(flags & (PIN_USER | PIN_GLOBAL)));

        /* First try and grab the pin without rebinding the vma */
        if (try_qad_pin(vma, flags & I915_VMA_BIND_MASK))
                return 0;

        err = vma_get_pages(vma);
        if (err)
                return err;

        if (flags & vma->vm->bind_async_flags) {
                work = i915_vma_work();
                if (!work) {
                        err = -ENOMEM;
                        goto err_pages;
                }
        }

        if (flags & PIN_GLOBAL)
                wakeref = intel_runtime_pm_get(&vma->vm->i915->runtime_pm);

        /* No more allocations allowed once we hold vm->mutex */
        err = mutex_lock_interruptible(&vma->vm->mutex);
        if (err)
                goto err_fence;

        bound = atomic_read(&vma->flags);
        if (unlikely(bound & I915_VMA_ERROR)) {
                err = -ENOMEM;
                goto err_unlock;
        }

        if (unlikely(!((bound + 1) & I915_VMA_PIN_MASK))) {
                err = -EAGAIN; /* pins are meant to be fairly temporary */
                goto err_unlock;
        }

        if (unlikely(!(flags & ~bound & I915_VMA_BIND_MASK))) {
                __i915_vma_pin(vma);
                goto err_unlock;
        }

        err = i915_active_acquire(&vma->active);
        if (err)
                goto err_unlock;

        if (!(bound & I915_VMA_BIND_MASK)) {
                err = i915_vma_insert(vma, size, alignment, flags);
                if (err)
                        goto err_active;

                if (i915_is_ggtt(vma->vm))
                        __i915_vma_set_map_and_fenceable(vma);
        }

        GEM_BUG_ON(!vma->pages);
        err = i915_vma_bind(vma,
                            vma->obj ? vma->obj->cache_level : 0,
                            flags, work);
        if (err)
                goto err_remove;

        /* There should only be at most 2 active bindings (user, global) */
        GEM_BUG_ON(bound + I915_VMA_PAGES_ACTIVE < bound);
        atomic_add(I915_VMA_PAGES_ACTIVE, &vma->pages_count);
        list_move_tail(&vma->vm_link, &vma->vm->bound_list);

        __i915_vma_pin(vma);
        GEM_BUG_ON(!i915_vma_is_pinned(vma));
        GEM_BUG_ON(!i915_vma_is_bound(vma, flags));
        GEM_BUG_ON(i915_vma_misplaced(vma, size, alignment, flags));

err_remove:
        if (!i915_vma_is_bound(vma, I915_VMA_BIND_MASK)) {
                i915_vma_detach(vma);
                drm_mm_remove_node(&vma->node);
        }
err_active:
        i915_active_release(&vma->active);
err_unlock:
        mutex_unlock(&vma->vm->mutex);
err_fence:
        if (work)
                dma_fence_work_commit(&work->base);
        if (wakeref)
                intel_runtime_pm_put(&vma->vm->i915->runtime_pm, wakeref);
err_pages:
        vma_put_pages(vma);
        return err;
}

static void flush_idle_contexts(struct intel_gt *gt)
{
        struct intel_engine_cs *engine;
        enum intel_engine_id id;

        for_each_engine(engine, gt, id)
                intel_engine_flush_barriers(engine);

        intel_gt_wait_for_idle(gt, MAX_SCHEDULE_TIMEOUT);
}

int i915_ggtt_pin(struct i915_vma *vma, u32 align, unsigned int flags)
{
        struct i915_address_space *vm = vma->vm;
        int err;

        GEM_BUG_ON(!i915_vma_is_ggtt(vma));

        do {
                err = i915_vma_pin(vma, 0, align, flags | PIN_GLOBAL);
                if (err != -ENOSPC)
                        return err;

                /* Unlike i915_vma_pin, we don't take no for an answer! */
                flush_idle_contexts(vm->gt);
                if (mutex_lock_interruptible(&vm->mutex) == 0) {
                        i915_gem_evict_vm(vm);
                        mutex_unlock(&vm->mutex);
                }
        } while (1);
}

void i915_vma_close(struct i915_vma *vma)
{
        struct intel_gt *gt = vma->vm->gt;
        unsigned long flags;

        GEM_BUG_ON(i915_vma_is_closed(vma));

        /*
         * We defer actually closing, unbinding and destroying the VMA until

         * the next idle point, or if the object is freed in the meantime. By
         * postponing the unbind, we allow for it to be resurrected by the
         * client, avoiding the work required to rebind the VMA. This is
         * advantageous for DRI, where the client/server pass objects
         * between themselves, temporarily opening a local VMA to the
         * object, and then closing it again. The same object is then reused
         * on the next frame (or two, depending on the depth of the swap queue)
         * causing us to rebind the VMA once more. This ends up being a lot
         * of wasted work for the steady state.
         */
        spin_lock_irqsave(&gt->closed_lock, flags);
        list_add(&vma->closed_link, &gt->closed_vma);
        spin_unlock_irqrestore(&gt->closed_lock, flags);
}

static void __i915_vma_remove_closed(struct i915_vma *vma)
{
        struct intel_gt *gt = vma->vm->gt;

        spin_lock_irq(&gt->closed_lock);
        list_del_init(&vma->closed_link);
        spin_unlock_irq(&gt->closed_lock);
}

void i915_vma_reopen(struct i915_vma *vma)
{
        if (i915_vma_is_closed(vma))
                __i915_vma_remove_closed(vma);
}

void i915_vma_release(struct kref *ref)
{
        struct i915_vma *vma = container_of(ref, typeof(*vma), ref);

        if (drm_mm_node_allocated(&vma->node)) {
                mutex_lock(&vma->vm->mutex);
                atomic_and(~I915_VMA_PIN_MASK, &vma->flags);
                WARN_ON(__i915_vma_unbind(vma));
                mutex_unlock(&vma->vm->mutex);
                GEM_BUG_ON(drm_mm_node_allocated(&vma->node));
        }
        GEM_BUG_ON(i915_vma_is_active(vma));

        if (vma->obj) {
                struct drm_i915_gem_object *obj = vma->obj;

                spin_lock(&obj->vma.lock);
                list_del(&vma->obj_link);
                rb_erase(&vma->obj_node, &obj->vma.tree);
                spin_unlock(&obj->vma.lock);
        }

        __i915_vma_remove_closed(vma);
        i915_vm_put(vma->vm);

        i915_active_fini(&vma->active);
        i915_vma_free(vma);
}

void i915_vma_parked(struct intel_gt *gt)
{
        struct i915_vma *vma, *next;

        spin_lock_irq(&gt->closed_lock);
        list_for_each_entry_safe(vma, next, &gt->closed_vma, closed_link) {
                struct drm_i915_gem_object *obj = vma->obj;
                struct i915_address_space *vm = vma->vm;

                /* XXX All to avoid keeping a reference on i915_vma itself */

                if (!kref_get_unless_zero(&obj->base.refcount))
                        continue;

                if (i915_vm_tryopen(vm)) {
                        list_del_init(&vma->closed_link);
                } else {
                        i915_gem_object_put(obj);
                        obj = NULL;
                }

                spin_unlock_irq(&gt->closed_lock);

                if (obj) {
                        __i915_vma_put(vma);
                        i915_gem_object_put(obj);
                }

                i915_vm_close(vm);

                /* Restart after dropping lock */
                spin_lock_irq(&gt->closed_lock);
                next = list_first_entry(&gt->closed_vma,
                                        typeof(*next), closed_link);
        }
        spin_unlock_irq(&gt->closed_lock);
}

static void __i915_vma_iounmap(struct i915_vma *vma)
{
        GEM_BUG_ON(i915_vma_is_pinned(vma));

        if (vma->iomap == NULL)
                return;

        io_mapping_unmap(vma->iomap);
        vma->iomap = NULL;
}

void i915_vma_revoke_mmap(struct i915_vma *vma)
{
        struct drm_vma_offset_node *node;
        u64 vma_offset;

        if (!i915_vma_has_userfault(vma))
                return;

        GEM_BUG_ON(!i915_vma_is_map_and_fenceable(vma));
        GEM_BUG_ON(!vma->obj->userfault_count);

        node = &vma->mmo->vma_node;
        vma_offset = vma->ggtt_view.partial.offset << PAGE_SHIFT;
        unmap_mapping_range(vma->vm->i915->drm.anon_inode->i_mapping,
                            drm_vma_node_offset_addr(node) + vma_offset,
                            vma->size,
                            1);

        i915_vma_unset_userfault(vma);
        if (!--vma->obj->userfault_count)
                list_del(&vma->obj->userfault_link);
}

int __i915_vma_move_to_active(struct i915_vma *vma, struct i915_request *rq)
{
        int err;

        GEM_BUG_ON(!i915_vma_is_pinned(vma));

        /* Wait for the vma to be bound before we start! */
        err = i915_request_await_active(rq, &vma->active);
        if (err)
                return err;

        return i915_active_add_request(&vma->active, rq);
}

int i915_vma_move_to_active(struct i915_vma *vma,
                            struct i915_request *rq,
                            unsigned int flags)
{
        struct drm_i915_gem_object *obj = vma->obj;
        int err;

        assert_object_held(obj);

        err = __i915_vma_move_to_active(vma, rq);
        if (unlikely(err))
                return err;

        if (flags & EXEC_OBJECT_WRITE) {
                struct intel_frontbuffer *front;

                front = __intel_frontbuffer_get(obj);
                if (unlikely(front)) {
                        if (intel_frontbuffer_invalidate(front, ORIGIN_CS))
                                i915_active_add_request(&front->write, rq);
                        intel_frontbuffer_put(front);
                }

                dma_resv_add_excl_fence(vma->resv, &rq->fence);
                obj->write_domain = I915_GEM_DOMAIN_RENDER;
                obj->read_domains = 0;
        } else {
                err = dma_resv_reserve_shared(vma->resv, 1);
                if (unlikely(err))
                        return err;

                dma_resv_add_shared_fence(vma->resv, &rq->fence);
                obj->write_domain = 0;
        }
        obj->read_domains |= I915_GEM_GPU_DOMAINS;
        obj->mm.dirty = true;

        GEM_BUG_ON(!i915_vma_is_active(vma));
        return 0;
}

int __i915_vma_unbind(struct i915_vma *vma)
{
        int ret;

        lockdep_assert_held(&vma->vm->mutex);

        /*
         * First wait upon any activity as retiring the request may
         * have side-effects such as unpinning or even unbinding this vma.
         *
         * XXX Actually waiting under the vm->mutex is a hinderance and
         * should be pipelined wherever possible. In cases where that is
         * unavoidable, we should lift the wait to before the mutex.
         */
        ret = i915_vma_sync(vma);
        if (ret)
                return ret;

        if (i915_vma_is_pinned(vma)) {
                vma_print_allocator(vma, "is pinned");
                return -EAGAIN;
        }

        /*
         * After confirming that no one else is pinning this vma, wait for
         * any laggards who may have crept in during the wait (through
         * a residual pin skipping the vm->mutex) to complete.
         */
        ret = i915_vma_sync(vma);
        if (ret)
                return ret;

        if (!drm_mm_node_allocated(&vma->node))
                return 0;

        GEM_BUG_ON(i915_vma_is_pinned(vma));
        GEM_BUG_ON(i915_vma_is_active(vma));

        if (i915_vma_is_map_and_fenceable(vma)) {
                /*
                 * Check that we have flushed all writes through the GGTT
                 * before the unbind, other due to non-strict nature of those
                 * indirect writes they may end up referencing the GGTT PTE
                 * after the unbind.
                 */
                i915_vma_flush_writes(vma);
                GEM_BUG_ON(i915_vma_has_ggtt_write(vma));

                /* release the fence reg _after_ flushing */
                ret = i915_vma_revoke_fence(vma);
                if (ret)
                        return ret;

                /* Force a pagefault for domain tracking on next user access */
                i915_vma_revoke_mmap(vma);

                __i915_vma_iounmap(vma);
                clear_bit(I915_VMA_CAN_FENCE_BIT, __i915_vma_flags(vma));
        }
        GEM_BUG_ON(vma->fence);
        GEM_BUG_ON(i915_vma_has_userfault(vma));

        if (likely(atomic_read(&vma->vm->open))) {
                trace_i915_vma_unbind(vma);
                vma->ops->unbind_vma(vma);
        }
        atomic_and(~(I915_VMA_BIND_MASK | I915_VMA_ERROR), &vma->flags);

        i915_vma_detach(vma);
        vma_unbind_pages(vma);

        drm_mm_remove_node(&vma->node); /* pairs with i915_vma_release() */
        return 0;
}

int i915_vma_unbind(struct i915_vma *vma)
{
        struct i915_address_space *vm = vma->vm;
        intel_wakeref_t wakeref = 0;
        int err;

        if (!drm_mm_node_allocated(&vma->node))
                return 0;

        if (i915_vma_is_bound(vma, I915_VMA_GLOBAL_BIND))
                /* XXX not always required: nop_clear_range */
                wakeref = intel_runtime_pm_get(&vm->i915->runtime_pm);

        err = mutex_lock_interruptible(&vm->mutex);
        if (err)
                return err;

        err = __i915_vma_unbind(vma);
        mutex_unlock(&vm->mutex);

        if (wakeref)
                intel_runtime_pm_put(&vm->i915->runtime_pm, wakeref);

        return err;
}

struct i915_vma *i915_vma_make_unshrinkable(struct i915_vma *vma)
{
        i915_gem_object_make_unshrinkable(vma->obj);
        return vma;
}

void i915_vma_make_shrinkable(struct i915_vma *vma)
{
        i915_gem_object_make_shrinkable(vma->obj);
}

void i915_vma_make_purgeable(struct i915_vma *vma)
{
        i915_gem_object_make_purgeable(vma->obj);
}

#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
#include "selftests/i915_vma.c"
#endif

static void i915_global_vma_shrink(void)
{
        kmem_cache_shrink(global.slab_vmas);
}

static void i915_global_vma_exit(void)
{
        kmem_cache_destroy(global.slab_vmas);
}

static struct i915_global_vma global = { {
        .shrink = i915_global_vma_shrink,
        .exit = i915_global_vma_exit,
} };

int __init i915_global_vma_init(void)
{
        global.slab_vmas = KMEM_CACHE(i915_vma, SLAB_HWCACHE_ALIGN);
        if (!global.slab_vmas)
                return -ENOMEM;

        i915_global_register(&global.base);
        return 0;
}