/*
 * 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 <linux/dma-fence-array.h>
#include <drm/drm_gem.h>

#include "display/intel_frontbuffer.h"
#include "gem/i915_gem_lmem.h"
#include "gem/i915_gem_tiling.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_gem_evict.h"
#include "i915_sw_fence_work.h"
#include "i915_trace.h"
#include "i915_vma.h"
#include "i915_vma_resource.h"

static inline void assert_vma_held_evict(const struct i915_vma *vma)
{
        /*
         * We may be forced to unbind when the vm is dead, to clean it up.
         * This is the only exception to the requirement of the object lock
         * being held.
         */
        if (kref_read(&vma->vm->ref))
                assert_object_held_shared(vma->obj);
}

static struct kmem_cache *slab_vmas;

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

static void i915_vma_free(struct i915_vma *vma)
{
        return kmem_cache_free(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)
{
        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;
        }

        stack_depot_snprint(vma->node.stack, buf, sizeof(buf), 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;
}

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 *pos = ERR_PTR(-E2BIG);
        struct i915_vma *vma;
        struct rb_node *rb, **p;
        int err;

        /* 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);

        vma->ops = &vm->vma_ops;
        vma->obj = obj;
        vma->size = obj->base.size;
        vma->display_alignment = I915_GTT_MIN_ALIGNMENT;

        i915_active_init(&vma->active, __i915_vma_active, __i915_vma_retire, 0);

        /* 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);
        INIT_LIST_HEAD(&vma->obj_link);
        RB_CLEAR_NODE(&vma->obj_node);

        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));

        err = mutex_lock_interruptible(&vm->mutex);
        if (err) {
                pos = ERR_PTR(err);
                goto err_vma;
        }

        vma->vm = vm;
        list_add_tail(&vma->vm_link, &vm->unbound_list);

        spin_lock(&obj->vma.lock);
        if (i915_is_ggtt(vm)) {
                if (unlikely(overflows_type(vma->size, u32)))
                        goto err_unlock;

                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_unlock;

                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));
        }

        rb = NULL;
        p = &obj->vma.tree.rb_node;
        while (*p) {
                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)
                        p = &rb->rb_right;
                else if (cmp > 0)
                        p = &rb->rb_left;
                else
                        goto err_unlock;
        }
        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);
        mutex_unlock(&vm->mutex);

        return vma;

err_unlock:
        spin_unlock(&obj->vma.lock);
        list_del_init(&vma->vm_link);
        mutex_unlock(&vm->mutex);
err_vma:
        i915_vma_free(vma);
        return pos;
}

static struct i915_vma *
i915_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_or_dpt(vm));
        GEM_BUG_ON(!kref_read(&vm->ref));

        spin_lock(&obj->vma.lock);
        vma = i915_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_address_space *vm;
        struct i915_vm_pt_stash stash;
        struct i915_vma_resource *vma_res;
        struct drm_i915_gem_object *pinned;
        struct i915_sw_dma_fence_cb cb;
        enum i915_cache_level cache_level;
        unsigned int flags;
};

static void __vma_bind(struct dma_fence_work *work)
{
        struct i915_vma_work *vw = container_of(work, typeof(*vw), base);
        struct i915_vma_resource *vma_res = vw->vma_res;

        vma_res->ops->bind_vma(vma_res->vm, &vw->stash,
                               vma_res, vw->cache_level, vw->flags);

}

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_put(vw->pinned);

        i915_vm_free_pt_stash(vw->vm, &vw->stash);
        if (vw->vma_res)
                i915_vma_resource_put(vw->vma_res);
}

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;
}

int i915_vma_wait_for_bind(struct i915_vma *vma)
{
        int err = 0;

        if (rcu_access_pointer(vma->active.excl.fence)) {
                struct dma_fence *fence;

                rcu_read_lock();
                fence = dma_fence_get_rcu_safe(&vma->active.excl.fence);
                rcu_read_unlock();
                if (fence) {
                        err = dma_fence_wait(fence, true);
                        dma_fence_put(fence);
                }
        }

        return err;
}

#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
static int i915_vma_verify_bind_complete(struct i915_vma *vma)
{
        struct dma_fence *fence = i915_active_fence_get(&vma->active.excl);
        int err;

        if (!fence)
                return 0;

        if (dma_fence_is_signaled(fence))
                err = fence->error;
        else
                err = -EBUSY;

        dma_fence_put(fence);

        return err;
}
#else
#define i915_vma_verify_bind_complete(_vma) 0
#endif

I915_SELFTEST_EXPORT void
i915_vma_resource_init_from_vma(struct i915_vma_resource *vma_res,
                                struct i915_vma *vma)
{
        struct drm_i915_gem_object *obj = vma->obj;

        i915_vma_resource_init(vma_res, vma->vm, vma->pages, &vma->page_sizes,
                               obj->mm.rsgt, i915_gem_object_is_readonly(obj),
                               i915_gem_object_is_lmem(obj), obj->mm.region,
                               vma->ops, vma->private, vma->node.start,
                               vma->node.size, vma->size);
}

/**
 * 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
 * @vma_res: pointer to a preallocated vma resource. The resource is either
 * consumed or freed.
 *
 * 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,
                  struct i915_vma_resource *vma_res)
{
        u32 bind_flags;
        u32 vma_flags;
        int ret;

        lockdep_assert_held(&vma->vm->mutex);
        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))) {
                i915_vma_resource_free(vma_res);
                return -ENODEV;
        }

        if (GEM_DEBUG_WARN_ON(!flags)) {
                i915_vma_resource_free(vma_res);
                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;

        bind_flags &= ~vma_flags;
        if (bind_flags == 0) {
                i915_vma_resource_free(vma_res);
                return 0;
        }

        GEM_BUG_ON(!atomic_read(&vma->pages_count));

        /* Wait for or await async unbinds touching our range */
        if (work && bind_flags & vma->vm->bind_async_flags)
                ret = i915_vma_resource_bind_dep_await(vma->vm,
                                                       &work->base.chain,
                                                       vma->node.start,
                                                       vma->node.size,
                                                       true,
                                                       GFP_NOWAIT |
                                                       __GFP_RETRY_MAYFAIL |
                                                       __GFP_NOWARN);
        else
                ret = i915_vma_resource_bind_dep_sync(vma->vm, vma->node.start,
                                                      vma->node.size, true);
        if (ret) {
                i915_vma_resource_free(vma_res);
                return ret;
        }

        if (vma->resource || !vma_res) {
                /* Rebinding with an additional I915_VMA_*_BIND */
                GEM_WARN_ON(!vma_flags);
                i915_vma_resource_free(vma_res);
        } else {
                i915_vma_resource_init_from_vma(vma_res, vma);
                vma->resource = vma_res;
        }
        trace_i915_vma_bind(vma, bind_flags);
        if (work && bind_flags & vma->vm->bind_async_flags) {
                struct dma_fence *prev;

                work->vma_res = i915_vma_resource_get(vma->resource);
                work->cache_level = cache_level;
                work->flags = bind_flags;

                /*
                 * 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.
                 */
                prev = i915_active_set_exclusive(&vma->active, &work->base.dma);
                if (prev) {
                        __i915_sw_fence_await_dma_fence(&work->base.chain,
                                                        prev,
                                                        &work->cb);
                        dma_fence_put(prev);
                }

                work->base.dma.error = 0; /* enable the queue_work() */

                /*
                 * If we don't have the refcounted pages list, keep a reference
                 * on the object to avoid waiting for the async bind to
                 * complete in the object destruction path.
                 */
                if (!work->vma_res->bi.pages_rsgt)
                        work->pinned = i915_gem_object_get(vma->obj);
        } else {
                ret = i915_gem_object_wait_moving_fence(vma->obj, true);
                if (ret) {
                        i915_vma_resource_free(vma->resource);
                        vma->resource = NULL;

                        return ret;
                }
                vma->ops->bind_vma(vma->vm, NULL, vma->resource, cache_level,
                                   bind_flags);
        }

        set_bit(I915_BO_WAS_BOUND_BIT, &vma->obj->flags);

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

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

        if (WARN_ON_ONCE(vma->obj->flags & I915_BO_ALLOC_GPU_ONLY))
                return IOMEM_ERR_PTR(-EINVAL);

        if (!i915_gem_object_is_lmem(vma->obj)) {
                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));
        GEM_BUG_ON(i915_vma_verify_bind_complete(vma));

        ptr = READ_ONCE(vma->iomap);
        if (ptr == NULL) {
                /*
                 * TODO: consider just using i915_gem_object_pin_map() for lmem
                 * instead, which already supports mapping non-contiguous chunks
                 * of pages, that way we can also drop the
                 * I915_BO_ALLOC_CONTIGUOUS when allocating the object.
                 */
                if (i915_gem_object_is_lmem(vma->obj))
                        ptr = i915_gem_object_lmem_io_map(vma->obj, 0,
                                                          vma->obj->base.size);
                else
                        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 IOMEM_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);

        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;
}

/**
 * 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, struct i915_gem_ww_ctx *ww,
                u64 size, u64 alignment, u64 flags)
{
        unsigned long color;
        u64 start, end;
        int ret;

        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));

        alignment = max(alignment, i915_vm_obj_min_alignment(vma->vm, vma->obj));
        /*
         * for compact-pt we round up the reservation to prevent
         * any smaller pages being used within the same PDE
         */
        if (NEEDS_COMPACT_PT(vma->vm->i915))
                size = round_up(size, alignment);

        /* 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 (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, ww, &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, ww, &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));

        list_move_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_move_tail(&vma->vm_link, &vma->vm->unbound_list);
}

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

        bound = atomic_read(&vma->flags);

        if (flags & PIN_VALIDATE) {
                flags &= I915_VMA_BIND_MASK;

                return (flags & bound) == flags;
        }

        /* with the lock mandatory for unbind, we don't race here */
        flags &= I915_VMA_BIND_MASK;
        do {
                if (unlikely(flags & ~bound))
                        return false;

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

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

        return true;
}

static struct scatterlist *
rotate_pages(struct drm_i915_gem_object *obj, unsigned int offset,
             unsigned int width, unsigned int height,
             unsigned int src_stride, unsigned int dst_stride,
             struct sg_table *st, struct scatterlist *sg)
{
        unsigned int column, row;
        unsigned int src_idx;

        for (column = 0; column < width; column++) {
                unsigned int left;

                src_idx = src_stride * (height - 1) + column + offset;
                for (row = 0; row < height; row++) {
                        st->nents++;
                        /*
                         * We don't need the pages, but need to initialize
                         * the entries so the sg list can be happily traversed.
                         * The only thing we need are DMA addresses.
                         */
                        sg_set_page(sg, NULL, I915_GTT_PAGE_SIZE, 0);
                        sg_dma_address(sg) =
                                i915_gem_object_get_dma_address(obj, src_idx);
                        sg_dma_len(sg) = I915_GTT_PAGE_SIZE;
                        sg = sg_next(sg);
                        src_idx -= src_stride;
                }

                left = (dst_stride - height) * I915_GTT_PAGE_SIZE;

                if (!left)
                        continue;

                st->nents++;

                /*
                 * The DE ignores the PTEs for the padding tiles, the sg entry
                 * here is just a conenience to indicate how many padding PTEs
                 * to insert at this spot.
                 */
                sg_set_page(sg, NULL, left, 0);
                sg_dma_address(sg) = 0;
                sg_dma_len(sg) = left;
                sg = sg_next(sg);
        }

        return sg;
}

static noinline struct sg_table *
intel_rotate_pages(struct intel_rotation_info *rot_info,
                   struct drm_i915_gem_object *obj)
{
        unsigned int size = intel_rotation_info_size(rot_info);
        struct drm_i915_private *i915 = to_i915(obj->base.dev);
        struct sg_table *st;
        struct scatterlist *sg;
        int ret = -ENOMEM;
        int i;

        /* Allocate target SG list. */
        st = kmalloc(sizeof(*st), GFP_KERNEL);
        if (!st)
                goto err_st_alloc;

        ret = sg_alloc_table(st, size, GFP_KERNEL);
        if (ret)
                goto err_sg_alloc;

        st->nents = 0;
        sg = st->sgl;

        for (i = 0 ; i < ARRAY_SIZE(rot_info->plane); i++)
                sg = rotate_pages(obj, rot_info->plane[i].offset,
                                  rot_info->plane[i].width, rot_info->plane[i].height,
                                  rot_info->plane[i].src_stride,
                                  rot_info->plane[i].dst_stride,
                                  st, sg);

        return st;

err_sg_alloc:
        kfree(st);
err_st_alloc:

        drm_dbg(&i915->drm, "Failed to create rotated mapping for object size %zu! (%ux%u tiles, %u pages)\n",
                obj->base.size, rot_info->plane[0].width,
                rot_info->plane[0].height, size);

        return ERR_PTR(ret);
}

static struct scatterlist *
add_padding_pages(unsigned int count,
                  struct sg_table *st, struct scatterlist *sg)
{
        st->nents++;

        /*
         * The DE ignores the PTEs for the padding tiles, the sg entry
         * here is just a convenience to indicate how many padding PTEs
         * to insert at this spot.
         */

        sg_set_page(sg, NULL, count * I915_GTT_PAGE_SIZE, 0);
        sg_dma_address(sg) = 0;
        sg_dma_len(sg) = count * I915_GTT_PAGE_SIZE;
        sg = sg_next(sg);

        return sg;
}

static struct scatterlist *
remap_tiled_color_plane_pages(struct drm_i915_gem_object *obj,
                              unsigned int offset, unsigned int alignment_pad,
                              unsigned int width, unsigned int height,
                              unsigned int src_stride, unsigned int dst_stride,
                              struct sg_table *st, struct scatterlist *sg,
                              unsigned int *gtt_offset)
{
        unsigned int row;

        if (!width || !height)
                return sg;

        if (alignment_pad)
                sg = add_padding_pages(alignment_pad, st, sg);

        for (row = 0; row < height; row++) {
                unsigned int left = width * I915_GTT_PAGE_SIZE;

                while (left) {
                        dma_addr_t addr;
                        unsigned int length;

                        /*
                         * We don't need the pages, but need to initialize
                         * the entries so the sg list can be happily traversed.
                         * The only thing we need are DMA addresses.
                         */

                        addr = i915_gem_object_get_dma_address_len(obj, offset, &length);

                        length = min(left, length);

                        st->nents++;

                        sg_set_page(sg, NULL, length, 0);
                        sg_dma_address(sg) = addr;
                        sg_dma_len(sg) = length;
                        sg = sg_next(sg);

                        offset += length / I915_GTT_PAGE_SIZE;
                        left -= length;
                }

                offset += src_stride - width;

                left = (dst_stride - width) * I915_GTT_PAGE_SIZE;

                if (!left)
                        continue;

                sg = add_padding_pages(left >> PAGE_SHIFT, st, sg);
        }

        *gtt_offset += alignment_pad + dst_stride * height;

        return sg;
}

static struct scatterlist *
remap_contiguous_pages(struct drm_i915_gem_object *obj,
                       unsigned int obj_offset,
                       unsigned int count,
                       struct sg_table *st, struct scatterlist *sg)
{
        struct scatterlist *iter;
        unsigned int offset;

        iter = i915_gem_object_get_sg_dma(obj, obj_offset, &offset);
        GEM_BUG_ON(!iter);

        do {
                unsigned int len;

                len = min(sg_dma_len(iter) - (offset << PAGE_SHIFT),
                          count << PAGE_SHIFT);
                sg_set_page(sg, NULL, len, 0);
                sg_dma_address(sg) =
                        sg_dma_address(iter) + (offset << PAGE_SHIFT);
                sg_dma_len(sg) = len;

                st->nents++;
                count -= len >> PAGE_SHIFT;
                if (count == 0)
                        return sg;

                sg = __sg_next(sg);
                iter = __sg_next(iter);
                offset = 0;
        } while (1);
}

static struct scatterlist *
remap_linear_color_plane_pages(struct drm_i915_gem_object *obj,
                               unsigned int obj_offset, unsigned int alignment_pad,
                               unsigned int size,
                               struct sg_table *st, struct scatterlist *sg,
                               unsigned int *gtt_offset)
{
        if (!size)
                return sg;

        if (alignment_pad)
                sg = add_padding_pages(alignment_pad, st, sg);

        sg = remap_contiguous_pages(obj, obj_offset, size, st, sg);
        sg = sg_next(sg);

        *gtt_offset += alignment_pad + size;

        return sg;
}

static struct scatterlist *
remap_color_plane_pages(const struct intel_remapped_info *rem_info,
                        struct drm_i915_gem_object *obj,
                        int color_plane,
                        struct sg_table *st, struct scatterlist *sg,
                        unsigned int *gtt_offset)
{
        unsigned int alignment_pad = 0;

        if (rem_info->plane_alignment)
                alignment_pad = ALIGN(*gtt_offset, rem_info->plane_alignment) - *gtt_offset;

        if (rem_info->plane[color_plane].linear)
                sg = remap_linear_color_plane_pages(obj,
                                                    rem_info->plane[color_plane].offset,
                                                    alignment_pad,
                                                    rem_info->plane[color_plane].size,
                                                    st, sg,
                                                    gtt_offset);

        else
                sg = remap_tiled_color_plane_pages(obj,
                                                   rem_info->plane[color_plane].offset,
                                                   alignment_pad,
                                                   rem_info->plane[color_plane].width,
                                                   rem_info->plane[color_plane].height,
                                                   rem_info->plane[color_plane].src_stride,
                                                   rem_info->plane[color_plane].dst_stride,
                                                   st, sg,
                                                   gtt_offset);

        return sg;
}

static noinline struct sg_table *
intel_remap_pages(struct intel_remapped_info *rem_info,
                  struct drm_i915_gem_object *obj)
{
        unsigned int size = intel_remapped_info_size(rem_info);
        struct drm_i915_private *i915 = to_i915(obj->base.dev);
        struct sg_table *st;
        struct scatterlist *sg;
        unsigned int gtt_offset = 0;
        int ret = -ENOMEM;
        int i;

        /* Allocate target SG list. */
        st = kmalloc(sizeof(*st), GFP_KERNEL);
        if (!st)
                goto err_st_alloc;

        ret = sg_alloc_table(st, size, GFP_KERNEL);
        if (ret)
                goto err_sg_alloc;

        st->nents = 0;
        sg = st->sgl;

        for (i = 0 ; i < ARRAY_SIZE(rem_info->plane); i++)
                sg = remap_color_plane_pages(rem_info, obj, i, st, sg, &gtt_offset);

        i915_sg_trim(st);

        return st;

err_sg_alloc:
        kfree(st);
err_st_alloc:

        drm_dbg(&i915->drm, "Failed to create remapped mapping for object size %zu! (%ux%u tiles, %u pages)\n",
                obj->base.size, rem_info->plane[0].width,
                rem_info->plane[0].height, size);

        return ERR_PTR(ret);
}

static noinline struct sg_table *
intel_partial_pages(const struct i915_ggtt_view *view,
                    struct drm_i915_gem_object *obj)
{
        struct sg_table *st;
        struct scatterlist *sg;
        unsigned int count = view->partial.size;
        int ret = -ENOMEM;

        st = kmalloc(sizeof(*st), GFP_KERNEL);
        if (!st)
                goto err_st_alloc;

        ret = sg_alloc_table(st, count, GFP_KERNEL);
        if (ret)
                goto err_sg_alloc;

        st->nents = 0;

        sg = remap_contiguous_pages(obj, view->partial.offset, count, st, st->sgl);

        sg_mark_end(sg);
        i915_sg_trim(st); /* Drop any unused tail entries. */

        return st;

err_sg_alloc:
        kfree(st);
err_st_alloc:
        return ERR_PTR(ret);
}

static int
__i915_vma_get_pages(struct i915_vma *vma)
{
        struct sg_table *pages;

        /*
         * The vma->pages are only valid within the lifespan of the borrowed
         * obj->mm.pages. When the obj->mm.pages sg_table is regenerated, so
         * must be the vma->pages. A simple rule is that vma->pages must only
         * be accessed when the obj->mm.pages are pinned.
         */
        GEM_BUG_ON(!i915_gem_object_has_pinned_pages(vma->obj));

        switch (vma->ggtt_view.type) {
        default:
                GEM_BUG_ON(vma->ggtt_view.type);
                fallthrough;
        case I915_GGTT_VIEW_NORMAL:
                pages = vma->obj->mm.pages;
                break;

        case I915_GGTT_VIEW_ROTATED:
                pages =
                        intel_rotate_pages(&vma->ggtt_view.rotated, vma->obj);
                break;

        case I915_GGTT_VIEW_REMAPPED:
                pages =
                        intel_remap_pages(&vma->ggtt_view.remapped, vma->obj);
                break;

        case I915_GGTT_VIEW_PARTIAL:
                pages = intel_partial_pages(&vma->ggtt_view, vma->obj);
                break;
        }

        if (IS_ERR(pages)) {
                drm_err(&vma->vm->i915->drm,
                        "Failed to get pages for VMA view type %u (%ld)!\n",
                        vma->ggtt_view.type, PTR_ERR(pages));
                return PTR_ERR(pages);
        }

        vma->pages = pages;

        return 0;
}

I915_SELFTEST_EXPORT int i915_vma_get_pages(struct i915_vma *vma)
{
        int err;

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

        err = i915_gem_object_pin_pages(vma->obj);
        if (err)
                return err;

        err = __i915_vma_get_pages(vma);
        if (err)
                goto err_unpin;

        vma->page_sizes = vma->obj->mm.page_sizes;
        atomic_inc(&vma->pages_count);

        return 0;

err_unpin:
        __i915_gem_object_unpin_pages(vma->obj);

        return err;
}

static void __vma_put_pages(struct i915_vma *vma, unsigned int count)
{
        /* We allocate under vma_get_pages, so beware the shrinker */
        GEM_BUG_ON(atomic_read(&vma->pages_count) < count);

        if (atomic_sub_return(count, &vma->pages_count) == 0) {
                if (vma->pages != vma->obj->mm.pages) {
                        sg_free_table(vma->pages);
                        kfree(vma->pages);
                }
                vma->pages = NULL;

                i915_gem_object_unpin_pages(vma->obj);
        }
}

I915_SELFTEST_EXPORT void i915_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_ww(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,
                    u64 size, u64 alignment, u64 flags)
{
        struct i915_vma_work *work = NULL;
        struct dma_fence *moving = NULL;
        struct i915_vma_resource *vma_res = NULL;
        intel_wakeref_t wakeref = 0;
        unsigned int bound;
        int err;

        assert_vma_held(vma);
        GEM_BUG_ON(!ww);

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

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

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

        err = i915_vma_get_pages(vma);
        if (err)
                return err;

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

        if (flags & vma->vm->bind_async_flags) {
                /* lock VM */
                err = i915_vm_lock_objects(vma->vm, ww);
                if (err)
                        goto err_rpm;

                work = i915_vma_work();
                if (!work) {
                        err = -ENOMEM;
                        goto err_rpm;
                }

                work->vm = vma->vm;

                err = i915_gem_object_get_moving_fence(vma->obj, &moving);
                if (err)
                        goto err_rpm;

                dma_fence_work_chain(&work->base, moving);

                /* Allocate enough page directories to used PTE */
                if (vma->vm->allocate_va_range) {
                        err = i915_vm_alloc_pt_stash(vma->vm,
                                                     &work->stash,
                                                     vma->size);
                        if (err)
                                goto err_fence;

                        err = i915_vm_map_pt_stash(vma->vm, &work->stash);
                        if (err)
                                goto err_fence;
                }
        }

        vma_res = i915_vma_resource_alloc();
        if (IS_ERR(vma_res)) {
                err = PTR_ERR(vma_res);
                goto err_fence;
        }

        /*
         * Differentiate between user/kernel vma inside the aliasing-ppgtt.
         *
         * We conflate the Global GTT with the user's vma when using the
         * aliasing-ppgtt, but it is still vitally important to try and
         * keep the use cases distinct. For example, userptr objects are
         * not allowed inside the Global GTT as that will cause lock
         * inversions when we have to evict them the mmu_notifier callbacks -
         * but they are allowed to be part of the user ppGTT which can never
         * be mapped. As such we try to give the distinct users of the same
         * mutex, distinct lockclasses [equivalent to how we keep i915_ggtt
         * and i915_ppgtt separate].
         *
         * NB this may cause us to mask real lock inversions -- while the
         * code is safe today, lockdep may not be able to spot future
         * transgressions.
         */
        err = mutex_lock_interruptible_nested(&vma->vm->mutex,
                                              !(flags & PIN_GLOBAL));
        if (err)
                goto err_vma_res;

        /* No more allocations allowed now we hold vm->mutex */

        if (unlikely(i915_vma_is_closed(vma))) {
                err = -ENOENT;
                goto err_unlock;
        }

        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))) {
                if (!(flags & PIN_VALIDATE))
                        __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, ww, 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->cache_level,
                            flags, work, vma_res);
        vma_res = NULL;
        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);

        if (!(flags & PIN_VALIDATE)) {
                __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_vma_res:
        i915_vma_resource_free(vma_res);
err_fence:
        if (work)
                dma_fence_work_commit_imm(&work->base);
err_rpm:
        if (wakeref)
                intel_runtime_pm_put(&vma->vm->i915->runtime_pm, wakeref);

        if (moving)
                dma_fence_put(moving);

        i915_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);
}

static int __i915_ggtt_pin(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,
                           u32 align, unsigned int flags)
{
        struct i915_address_space *vm = vma->vm;
        int err;

        do {
                err = i915_vma_pin_ww(vma, ww, 0, align, flags | PIN_GLOBAL);

                if (err != -ENOSPC) {
                        if (!err) {
                                err = i915_vma_wait_for_bind(vma);
                                if (err)
                                        i915_vma_unpin(vma);
                        }
                        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) {
                        /*
                         * We pass NULL ww here, as we don't want to unbind
                         * locked objects when called from execbuf when pinning
                         * is removed. This would probably regress badly.
                         */
                        i915_gem_evict_vm(vm, NULL);
                        mutex_unlock(&vm->mutex);
                }
        } while (1);
}

int i915_ggtt_pin(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,
                  u32 align, unsigned int flags)
{
        struct i915_gem_ww_ctx _ww;
        int err;

        GEM_BUG_ON(!i915_vma_is_ggtt(vma));

        if (ww)
                return __i915_ggtt_pin(vma, ww, align, flags);

        lockdep_assert_not_held(&vma->obj->base.resv->lock.base);

        for_i915_gem_ww(&_ww, err, true) {
                err = i915_gem_object_lock(vma->obj, &_ww);
                if (!err)
                        err = __i915_ggtt_pin(vma, &_ww, align, flags);
        }

        return err;
}

static void __vma_close(struct i915_vma *vma, struct intel_gt *gt)
{
        /*
         * 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.
         */
        GEM_BUG_ON(i915_vma_is_closed(vma));
        list_add(&vma->closed_link, &gt->closed_vma);
}

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

        if (i915_vma_is_ggtt(vma))
                return;

        GEM_BUG_ON(!atomic_read(&vma->open_count));
        if (atomic_dec_and_lock_irqsave(&vma->open_count,
                                        &gt->closed_lock,
                                        flags)) {
                __vma_close(vma, gt);
                spin_unlock_irqrestore(&gt->closed_lock, flags);
        }
}

static void __i915_vma_remove_closed(struct i915_vma *vma)
{
        list_del_init(&vma->closed_link);
}

void i915_vma_reopen(struct i915_vma *vma)
{
        struct intel_gt *gt = vma->vm->gt;

        spin_lock_irq(&gt->closed_lock);
        if (i915_vma_is_closed(vma))
                __i915_vma_remove_closed(vma);
        spin_unlock_irq(&gt->closed_lock);
}

static void force_unbind(struct i915_vma *vma)
{
        if (!drm_mm_node_allocated(&vma->node))
                return;

        atomic_and(~I915_VMA_PIN_MASK, &vma->flags);
        WARN_ON(__i915_vma_unbind(vma));
        GEM_BUG_ON(drm_mm_node_allocated(&vma->node));
}

static void release_references(struct i915_vma *vma, struct intel_gt *gt,
                               bool vm_ddestroy)
{
        struct drm_i915_gem_object *obj = vma->obj;

        GEM_BUG_ON(i915_vma_is_active(vma));

        spin_lock(&obj->vma.lock);
        list_del(&vma->obj_link);
        if (!RB_EMPTY_NODE(&vma->obj_node))
                rb_erase(&vma->obj_node, &obj->vma.tree);

        spin_unlock(&obj->vma.lock);

        spin_lock_irq(&gt->closed_lock);
        __i915_vma_remove_closed(vma);
        spin_unlock_irq(&gt->closed_lock);

        if (vm_ddestroy)
                i915_vm_resv_put(vma->vm);

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

/**
 * i915_vma_destroy_locked - Remove all weak reference to the vma and put
 * the initial reference.
 *
 * This function should be called when it's decided the vma isn't needed
 * anymore. The caller must assure that it doesn't race with another lookup
 * plus destroy, typically by taking an appropriate reference.
 *
 * Current callsites are
 * - __i915_gem_object_pages_fini()
 * - __i915_vm_close() - Blocks the above function by taking a reference on
 * the object.
 * - __i915_vma_parked() - Blocks the above functions by taking a reference
 * on the vm and a reference on the object. Also takes the object lock so
 * destruction from __i915_vma_parked() can be blocked by holding the
 * object lock. Since the object lock is only allowed from within i915 with
 * an object refcount, holding the object lock also implicitly blocks the
 * vma freeing from __i915_gem_object_pages_fini().
 *
 * Because of locks taken during destruction, a vma is also guaranteed to
 * stay alive while the following locks are held if it was looked up while
 * holding one of the locks:
 * - vm->mutex
 * - obj->vma.lock
 * - gt->closed_lock
 */
void i915_vma_destroy_locked(struct i915_vma *vma)
{
        lockdep_assert_held(&vma->vm->mutex);

        force_unbind(vma);
        list_del_init(&vma->vm_link);
        release_references(vma, vma->vm->gt, false);
}

void i915_vma_destroy(struct i915_vma *vma)
{
        struct intel_gt *gt;
        bool vm_ddestroy;

        mutex_lock(&vma->vm->mutex);
        force_unbind(vma);
        list_del_init(&vma->vm_link);
        vm_ddestroy = vma->vm_ddestroy;
        vma->vm_ddestroy = false;

        /* vma->vm may be freed when releasing vma->vm->mutex. */
        gt = vma->vm->gt;
        mutex_unlock(&vma->vm->mutex);
        release_references(vma, gt, vm_ddestroy);
}

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

        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_tryget(vm)) {
                        i915_gem_object_put(obj);
                        continue;
                }

                list_move(&vma->closed_link, &closed);
        }
        spin_unlock_irq(&gt->closed_lock);

        /* As the GT is held idle, no vma can be reopened as we destroy them */
        list_for_each_entry_safe(vma, next, &closed, closed_link) {
                struct drm_i915_gem_object *obj = vma->obj;
                struct i915_address_space *vm = vma->vm;

                if (i915_gem_object_trylock(obj, NULL)) {
                        INIT_LIST_HEAD(&vma->closed_link);
                        i915_vma_destroy(vma);
                        i915_gem_object_unlock(obj);
                } else {
                        /* back you go.. */
                        spin_lock_irq(&gt->closed_lock);
                        list_add(&vma->closed_link, &gt->closed_vma);
                        spin_unlock_irq(&gt->closed_lock);
                }

                i915_gem_object_put(obj);
                i915_vm_put(vm);
        }
}

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);
}

static int
__i915_request_await_bind(struct i915_request *rq, struct i915_vma *vma)
{
        return __i915_request_await_exclusive(rq, &vma->active);
}

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

        /* Wait for the vma to be bound before we start! */
        err = __i915_request_await_bind(rq, vma);
        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,
                             struct dma_fence *fence,
                             unsigned int flags)
{
        struct drm_i915_gem_object *obj = vma->obj;
        int err;

        assert_object_held(obj);

        GEM_BUG_ON(!vma->pages);

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

        /*
         * Reserve fences slot early to prevent an allocation after preparing
         * the workload and associating fences with dma_resv.
         */
        if (fence && !(flags & __EXEC_OBJECT_NO_RESERVE)) {
                struct dma_fence *curr;
                int idx;

                dma_fence_array_for_each(curr, idx, fence)
                        ;
                err = dma_resv_reserve_fences(vma->obj->base.resv, idx);
                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);
                }
        }

        if (fence) {
                struct dma_fence *curr;
                enum dma_resv_usage usage;
                int idx;

                obj->read_domains = 0;
                if (flags & EXEC_OBJECT_WRITE) {
                        usage = DMA_RESV_USAGE_WRITE;
                        obj->write_domain = I915_GEM_DOMAIN_RENDER;
                } else {
                        usage = DMA_RESV_USAGE_READ;
                }

                dma_fence_array_for_each(curr, idx, fence)
                        dma_resv_add_fence(vma->obj->base.resv, curr, usage);
        }

        if (flags & EXEC_OBJECT_NEEDS_FENCE && vma->fence)
                i915_active_add_request(&vma->fence->active, rq);

        obj->read_domains |= I915_GEM_GPU_DOMAINS;
        obj->mm.dirty = true;

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

struct dma_fence *__i915_vma_evict(struct i915_vma *vma, bool async)
{
        struct i915_vma_resource *vma_res = vma->resource;
        struct dma_fence *unbind_fence;

        GEM_BUG_ON(i915_vma_is_pinned(vma));
        assert_vma_held_evict(vma);

        if (i915_vma_is_map_and_fenceable(vma)) {
                /* Force a pagefault for domain tracking on next user access */
                i915_vma_revoke_mmap(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.
                 *
                 * Note that we may be concurrently poking at the GGTT_WRITE
                 * bit from set-domain, as we mark all GGTT vma associated
                 * with an object. We know this is for another vma, as we
                 * are currently unbinding this one -- so if this vma will be
                 * reused, it will be refaulted and have its dirty bit set
                 * before the next write.
                 */
                i915_vma_flush_writes(vma);

                /* release the fence reg _after_ flushing */
                i915_vma_revoke_fence(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));

        /* Object backend must be async capable. */
        GEM_WARN_ON(async && !vma->resource->bi.pages_rsgt);

        /* If vm is not open, unbind is a nop. */
        vma_res->needs_wakeref = i915_vma_is_bound(vma, I915_VMA_GLOBAL_BIND) &&
                kref_read(&vma->vm->ref);
        vma_res->skip_pte_rewrite = !kref_read(&vma->vm->ref) ||
                vma->vm->skip_pte_rewrite;
        trace_i915_vma_unbind(vma);

        unbind_fence = i915_vma_resource_unbind(vma_res);
        vma->resource = NULL;

        atomic_and(~(I915_VMA_BIND_MASK | I915_VMA_ERROR | I915_VMA_GGTT_WRITE),
                   &vma->flags);

        i915_vma_detach(vma);

        if (!async && unbind_fence) {
                dma_fence_wait(unbind_fence, false);
                dma_fence_put(unbind_fence);
                unbind_fence = NULL;
        }

        /*
         * Binding itself may not have completed until the unbind fence signals,
         * so don't drop the pages until that happens, unless the resource is
         * async_capable.
         */

        vma_unbind_pages(vma);
        return unbind_fence;
}

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

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

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

        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;

        GEM_BUG_ON(i915_vma_is_active(vma));
        __i915_vma_evict(vma, false);

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

static struct dma_fence *__i915_vma_unbind_async(struct i915_vma *vma)
{
        struct dma_fence *fence;

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

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

        if (i915_vma_is_pinned(vma) ||
            &vma->obj->mm.rsgt->table != vma->resource->bi.pages)
                return ERR_PTR(-EAGAIN);

        /*
         * We probably need to replace this with awaiting the fences of the
         * object's dma_resv when the vma active goes away. When doing that

         * we need to be careful to not add the vma_resource unbind fence
         * immediately to the object's dma_resv, because then unbinding
         * the next vma from the object, in case there are many, will
         * actually await the unbinding of the previous vmas, which is
         * undesirable.
         */
        if (i915_sw_fence_await_active(&vma->resource->chain, &vma->active,
                                       I915_ACTIVE_AWAIT_EXCL |
                                       I915_ACTIVE_AWAIT_ACTIVE) < 0) {
                return ERR_PTR(-EBUSY);
        }

        fence = __i915_vma_evict(vma, true);

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

        return fence;
}

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

        assert_object_held_shared(vma->obj);

        /* Optimistic wait before taking the mutex */
        err = i915_vma_sync(vma);
        if (err)
                return err;

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

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

        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_nested(&vma->vm->mutex, !wakeref);
        if (err)
                goto out_rpm;

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

out_rpm:
        if (wakeref)
                intel_runtime_pm_put(&vm->i915->runtime_pm, wakeref);
        return err;
}

int i915_vma_unbind_async(struct i915_vma *vma, bool trylock_vm)
{
        struct drm_i915_gem_object *obj = vma->obj;
        struct i915_address_space *vm = vma->vm;
        intel_wakeref_t wakeref = 0;
        struct dma_fence *fence;
        int err;

        /*
         * We need the dma-resv lock since we add the
         * unbind fence to the dma-resv object.
         */
        assert_object_held(obj);

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

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

        if (!obj->mm.rsgt)
                return -EBUSY;

        err = dma_resv_reserve_fences(obj->base.resv, 1);
        if (err)
                return -EBUSY;

        /*
         * It would be great if we could grab this wakeref from the
         * async unbind work if needed, but we can't because it uses
         * kmalloc and it's in the dma-fence signalling critical path.
         */
        if (i915_vma_is_bound(vma, I915_VMA_GLOBAL_BIND))
                wakeref = intel_runtime_pm_get(&vm->i915->runtime_pm);

        if (trylock_vm && !mutex_trylock(&vm->mutex)) {
                err = -EBUSY;
                goto out_rpm;
        } else if (!trylock_vm) {
                err = mutex_lock_interruptible_nested(&vm->mutex, !wakeref);
                if (err)
                        goto out_rpm;
        }

        fence = __i915_vma_unbind_async(vma);
        mutex_unlock(&vm->mutex);
        if (IS_ERR_OR_NULL(fence)) {
                err = PTR_ERR_OR_ZERO(fence);
                goto out_rpm;
        }

        dma_resv_add_fence(obj->base.resv, fence, DMA_RESV_USAGE_READ);
        dma_fence_put(fence);

out_rpm:
        if (wakeref)
                intel_runtime_pm_put(&vm->i915->runtime_pm, wakeref);
        return err;
}

int i915_vma_unbind_unlocked(struct i915_vma *vma)
{
        int err;

        i915_gem_object_lock(vma->obj, NULL);
        err = i915_vma_unbind(vma);
        i915_gem_object_unlock(vma->obj);

        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

void i915_vma_module_exit(void)
{
        kmem_cache_destroy(slab_vmas);
}

int __init i915_vma_module_init(void)
{
        slab_vmas = KMEM_CACHE(i915_vma, SLAB_HWCACHE_ALIGN);
        if (!slab_vmas)
                return -ENOMEM;

        return 0;
}