/* SPDX-License-Identifier: GPL-2.0 OR MIT */
/**************************************************************************
 *
 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
 * All Rights Reserved.
 *
 * 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, sub license, 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 NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS 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.
 *
 **************************************************************************/
/*
 * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
 */

#define pr_fmt(fmt) "[TTM] " fmt

#include <drm/drm_print.h>
#include <drm/ttm/ttm_allocation.h>
#include <drm/ttm/ttm_bo.h>
#include <drm/ttm/ttm_placement.h>
#include <drm/ttm/ttm_tt.h>

#include <linux/export.h>
#include <linux/jiffies.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/file.h>
#include <linux/module.h>
#include <linux/atomic.h>
#include <linux/cgroup_dmem.h>
#include <linux/dma-resv.h>

#include "ttm_module.h"
#include "ttm_bo_internal.h"

static void ttm_bo_mem_space_debug(struct ttm_buffer_object *bo,
                                        struct ttm_placement *placement)
{
        struct drm_printer p = drm_dbg_printer(NULL, DRM_UT_CORE, TTM_PFX);
        struct ttm_resource_manager *man;
        int i, mem_type;

        for (i = 0; i < placement->num_placement; i++) {
                mem_type = placement->placement[i].mem_type;
                drm_printf(&p, "  placement[%d]=0x%08X (%d)\n",
                           i, placement->placement[i].flags, mem_type);
                man = ttm_manager_type(bo->bdev, mem_type);
                ttm_resource_manager_debug(man, &p);
        }
}

/**
 * ttm_bo_move_to_lru_tail
 *
 * @bo: The buffer object.
 *
 * Move this BO to the tail of all lru lists used to lookup and reserve an
 * object. This function must be called with struct ttm_global::lru_lock
 * held, and is used to make a BO less likely to be considered for eviction.
 */
void ttm_bo_move_to_lru_tail(struct ttm_buffer_object *bo)
{
        dma_resv_assert_held(bo->base.resv);

        if (bo->resource)
                ttm_resource_move_to_lru_tail(bo->resource);
}
EXPORT_SYMBOL(ttm_bo_move_to_lru_tail);

/**
 * ttm_bo_set_bulk_move - update BOs bulk move object
 *
 * @bo: The buffer object.
 * @bulk: bulk move structure
 *
 * Update the BOs bulk move object, making sure that resources are added/removed
 * as well. A bulk move allows to move many resource on the LRU at once,
 * resulting in much less overhead of maintaining the LRU.
 * The only requirement is that the resources stay together on the LRU and are
 * never separated. This is enforces by setting the bulk_move structure on a BO.
 * ttm_lru_bulk_move_tail() should be used to move all resources to the tail of
 * their LRU list.
 */
void ttm_bo_set_bulk_move(struct ttm_buffer_object *bo,
                          struct ttm_lru_bulk_move *bulk)
{
        dma_resv_assert_held(bo->base.resv);

        if (bo->bulk_move == bulk)
                return;

        spin_lock(&bo->bdev->lru_lock);
        if (bo->resource)
                ttm_resource_del_bulk_move(bo->resource, bo);
        bo->bulk_move = bulk;
        if (bo->resource)
                ttm_resource_add_bulk_move(bo->resource, bo);
        spin_unlock(&bo->bdev->lru_lock);
}
EXPORT_SYMBOL(ttm_bo_set_bulk_move);

static int ttm_bo_handle_move_mem(struct ttm_buffer_object *bo,
                                  struct ttm_resource *mem, bool evict,
                                  struct ttm_operation_ctx *ctx,
                                  struct ttm_place *hop)
{
        struct ttm_device *bdev = bo->bdev;
        bool old_use_tt, new_use_tt;
        int ret;

        old_use_tt = !bo->resource || ttm_manager_type(bdev, bo->resource->mem_type)->use_tt;
        new_use_tt = ttm_manager_type(bdev, mem->mem_type)->use_tt;

        ttm_bo_unmap_virtual(bo);

        /*
         * Create and bind a ttm if required.
         */

        if (new_use_tt) {
                /* Zero init the new TTM structure if the old location should
                 * have used one as well.
                 */
                ret = ttm_tt_create(bo, old_use_tt);
                if (ret)
                        goto out_err;

                if (mem->mem_type != TTM_PL_SYSTEM) {
                        ret = ttm_bo_populate(bo, ctx);
                        if (ret)
                                goto out_err;
                }
        }

        ret = dma_resv_reserve_fences(bo->base.resv, 1);
        if (ret)
                goto out_err;

        ret = bdev->funcs->move(bo, evict, ctx, mem, hop);
        if (ret) {
                if (ret == -EMULTIHOP)
                        return ret;
                goto out_err;
        }

        ctx->bytes_moved += bo->base.size;
        return 0;

out_err:
        if (!old_use_tt)
                ttm_bo_tt_destroy(bo);

        return ret;
}

/*
 * Call bo::reserved.
 * Will release GPU memory type usage on destruction.
 * This is the place to put in driver specific hooks to release
 * driver private resources.
 * Will release the bo::reserved lock.
 */

static void ttm_bo_cleanup_memtype_use(struct ttm_buffer_object *bo)
{
        if (bo->bdev->funcs->delete_mem_notify)
                bo->bdev->funcs->delete_mem_notify(bo);

        ttm_bo_tt_destroy(bo);
        ttm_resource_free(bo, &bo->resource);
}

static int ttm_bo_individualize_resv(struct ttm_buffer_object *bo)
{
        int r;

        if (bo->base.resv == &bo->base._resv)
                return 0;

        BUG_ON(!dma_resv_trylock(&bo->base._resv));

        r = dma_resv_copy_fences(&bo->base._resv, bo->base.resv);
        dma_resv_unlock(&bo->base._resv);
        if (r)
                return r;

        if (bo->type != ttm_bo_type_sg) {
                /* This works because the BO is about to be destroyed and nobody
                 * reference it any more. The only tricky case is the trylock on
                 * the resv object while holding the lru_lock.
                 */
                spin_lock(&bo->bdev->lru_lock);
                bo->base.resv = &bo->base._resv;
                spin_unlock(&bo->bdev->lru_lock);
        }

        return r;
}

static void ttm_bo_flush_all_fences(struct ttm_buffer_object *bo)
{
        struct dma_resv *resv = &bo->base._resv;
        struct dma_resv_iter cursor;
        struct dma_fence *fence;

        dma_resv_iter_begin(&cursor, resv, DMA_RESV_USAGE_BOOKKEEP);
        dma_resv_for_each_fence_unlocked(&cursor, fence) {
                if (!fence->ops->signaled)
                        dma_fence_enable_sw_signaling(fence);
        }
        dma_resv_iter_end(&cursor);
}

/*
 * Block for the dma_resv object to become idle, lock the buffer and clean up
 * the resource and tt object.
 */
static void ttm_bo_delayed_delete(struct work_struct *work)
{
        struct ttm_buffer_object *bo;

        bo = container_of(work, typeof(*bo), delayed_delete);

        dma_resv_wait_timeout(&bo->base._resv, DMA_RESV_USAGE_BOOKKEEP, false,
                              MAX_SCHEDULE_TIMEOUT);
        dma_resv_lock(bo->base.resv, NULL);
        ttm_bo_cleanup_memtype_use(bo);
        dma_resv_unlock(bo->base.resv);
        ttm_bo_put(bo);
}

static void ttm_bo_release(struct kref *kref)
{
        struct ttm_buffer_object *bo =
            container_of(kref, struct ttm_buffer_object, kref);
        struct ttm_device *bdev = bo->bdev;
        int ret;

        WARN_ON_ONCE(bo->pin_count);
        WARN_ON_ONCE(bo->bulk_move);

        if (!bo->deleted) {
                ret = ttm_bo_individualize_resv(bo);
                if (ret) {
                        /* Last resort, if we fail to allocate memory for the
                         * fences block for the BO to become idle
                         */
                        dma_resv_wait_timeout(bo->base.resv,
                                              DMA_RESV_USAGE_BOOKKEEP, false,
                                              30 * HZ);
                }

                if (bdev->funcs->release_notify)
                        bdev->funcs->release_notify(bo);

                drm_vma_offset_remove(bdev->vma_manager, &bo->base.vma_node);
                ttm_mem_io_free(bdev, bo->resource);

                if (!dma_resv_test_signaled(&bo->base._resv,
                                            DMA_RESV_USAGE_BOOKKEEP) ||
                    (want_init_on_free() && (bo->ttm != NULL)) ||
                    bo->type == ttm_bo_type_sg ||
                    !dma_resv_trylock(bo->base.resv)) {
                        /* The BO is not idle, resurrect it for delayed destroy */
                        ttm_bo_flush_all_fences(bo);
                        bo->deleted = true;

                        spin_lock(&bdev->lru_lock);

                        /*
                         * Make pinned bos immediately available to
                         * shrinkers, now that they are queued for
                         * destruction.
                         *
                         * FIXME: QXL is triggering this. Can be removed when the
                         * driver is fixed.
                         */
                        if (bo->pin_count) {
                                bo->pin_count = 0;
                                ttm_resource_move_to_lru_tail(bo->resource);
                        }

                        kref_init(&bo->kref);
                        spin_unlock(&bdev->lru_lock);

                        INIT_WORK(&bo->delayed_delete, ttm_bo_delayed_delete);

                        /* Schedule the worker on the closest NUMA node. This
                         * improves performance since system memory might be
                         * cleared on free and that is best done on a CPU core
                         * close to it.
                         */
                        queue_work_node(bdev->pool.nid, bdev->wq, &bo->delayed_delete);
                        return;
                }

                ttm_bo_cleanup_memtype_use(bo);
                dma_resv_unlock(bo->base.resv);
        }

        atomic_dec(&ttm_glob.bo_count);
        bo->destroy(bo);
}

/* TODO: remove! */
void ttm_bo_put(struct ttm_buffer_object *bo)
{
        kref_put(&bo->kref, ttm_bo_release);
}

void ttm_bo_fini(struct ttm_buffer_object *bo)
{
        ttm_bo_put(bo);
}
EXPORT_SYMBOL(ttm_bo_fini);

static int ttm_bo_bounce_temp_buffer(struct ttm_buffer_object *bo,
                                     struct ttm_operation_ctx *ctx,
                                     struct ttm_place *hop)
{
        struct ttm_placement hop_placement;
        struct ttm_resource *hop_mem;
        int ret;

        hop_placement.num_placement = 1;
        hop_placement.placement = hop;

        /* find space in the bounce domain */
        ret = ttm_bo_mem_space(bo, &hop_placement, &hop_mem, ctx);
        if (ret)
                return ret;
        /* move to the bounce domain */
        ret = ttm_bo_handle_move_mem(bo, hop_mem, false, ctx, NULL);
        if (ret) {
                ttm_resource_free(bo, &hop_mem);
                return ret;
        }
        return 0;
}

static int ttm_bo_evict(struct ttm_buffer_object *bo,
                        struct ttm_operation_ctx *ctx)
{
        struct ttm_resource *evict_mem;
        struct ttm_placement placement;
        struct ttm_place hop;
        int ret = 0;

        memset(&hop, 0, sizeof(hop));

        dma_resv_assert_held(bo->base.resv);

        placement.num_placement = 0;
        bo->bdev->funcs->evict_flags(bo, &placement);

        if (!placement.num_placement) {
                ret = ttm_bo_wait_ctx(bo, ctx);
                if (ret)
                        return ret;

                /*
                 * Since we've already synced, this frees backing store
                 * immediately.
                 */
                return ttm_bo_pipeline_gutting(bo);
        }

        ret = ttm_bo_mem_space(bo, &placement, &evict_mem, ctx);
        if (ret) {
                if (ret != -ERESTARTSYS) {
                        pr_err("Failed to find memory space for buffer 0x%p eviction\n",
                               bo);
                        ttm_bo_mem_space_debug(bo, &placement);
                }
                goto out;
        }

        do {
                ret = ttm_bo_handle_move_mem(bo, evict_mem, true, ctx, &hop);
                if (ret != -EMULTIHOP)
                        break;

                ret = ttm_bo_bounce_temp_buffer(bo, ctx, &hop);
        } while (!ret);

        if (ret) {
                ttm_resource_free(bo, &evict_mem);
                if (ret != -ERESTARTSYS && ret != -EINTR)
                        pr_err("Buffer eviction failed\n");
        }
out:
        return ret;
}

/**
 * ttm_bo_eviction_valuable
 *
 * @bo: The buffer object to evict
 * @place: the placement we need to make room for
 *
 * Check if it is valuable to evict the BO to make room for the given placement.
 */
bool ttm_bo_eviction_valuable(struct ttm_buffer_object *bo,
                              const struct ttm_place *place)
{
        struct ttm_resource *res = bo->resource;

        dma_resv_assert_held(bo->base.resv);

        if (res->mem_type == TTM_PL_SYSTEM)
                return true;

        /* Don't evict this BO if it's outside of the
         * requested placement range
         */
        return ttm_resource_intersects(bo->bdev, res, place, bo->base.size);
}
EXPORT_SYMBOL(ttm_bo_eviction_valuable);

/**
 * ttm_bo_evict_first() - Evict the first bo on the manager's LRU list.
 * @bdev: The ttm device.
 * @man: The manager whose bo to evict.
 * @ctx: The TTM operation ctx governing the eviction.
 *
 * Return: 0 if successful or the resource disappeared. Negative error code on error.
 */
int ttm_bo_evict_first(struct ttm_device *bdev, struct ttm_resource_manager *man,
                       struct ttm_operation_ctx *ctx)
{
        struct ttm_resource_cursor cursor;
        struct ttm_buffer_object *bo;
        struct ttm_resource *res;
        unsigned int mem_type;
        int ret = 0;

        spin_lock(&bdev->lru_lock);
        ttm_resource_cursor_init(&cursor, man);
        res = ttm_resource_manager_first(&cursor);
        ttm_resource_cursor_fini(&cursor);
        if (!res) {
                ret = -ENOENT;
                goto out_no_ref;
        }
        bo = res->bo;
        if (!ttm_bo_get_unless_zero(bo))
                goto out_no_ref;
        mem_type = res->mem_type;
        spin_unlock(&bdev->lru_lock);
        ret = ttm_bo_reserve(bo, ctx->interruptible, ctx->no_wait_gpu, NULL);
        if (ret)
                goto out_no_lock;
        if (!bo->resource || bo->resource->mem_type != mem_type)
                goto out_bo_moved;

        if (bo->deleted) {
                ret = ttm_bo_wait_ctx(bo, ctx);
                if (!ret)
                        ttm_bo_cleanup_memtype_use(bo);
        } else {
                ret = ttm_bo_evict(bo, ctx);
        }
out_bo_moved:
        dma_resv_unlock(bo->base.resv);
out_no_lock:
        ttm_bo_put(bo);
        return ret;

out_no_ref:
        spin_unlock(&bdev->lru_lock);
        return ret;
}

/**
 * struct ttm_bo_evict_walk - Parameters for the evict walk.
 */
struct ttm_bo_evict_walk {
        /** @walk: The walk base parameters. */
        struct ttm_lru_walk walk;
        /** @place: The place passed to the resource allocation. */
        const struct ttm_place *place;
        /** @evictor: The buffer object we're trying to make room for. */
        struct ttm_buffer_object *evictor;
        /** @res: The allocated resource if any. */
        struct ttm_resource **res;
        /** @evicted: Number of successful evictions. */
        unsigned long evicted;

        /** @limit_pool: Which pool limit we should test against */
        struct dmem_cgroup_pool_state *limit_pool;
        /** @try_low: Whether we should attempt to evict BO's with low watermark threshold */
        bool try_low;
        /** @hit_low: If we cannot evict a bo when @try_low is false (first pass) */
        bool hit_low;
};

static s64 ttm_bo_evict_cb(struct ttm_lru_walk *walk, struct ttm_buffer_object *bo)
{
        struct ttm_bo_evict_walk *evict_walk =
                container_of(walk, typeof(*evict_walk), walk);
        s64 lret;

        if (!dmem_cgroup_state_evict_valuable(evict_walk->limit_pool, bo->resource->css,
                                              evict_walk->try_low, &evict_walk->hit_low))
                return 0;

        if (bo->pin_count || !bo->bdev->funcs->eviction_valuable(bo, evict_walk->place))
                return 0;

        if (bo->deleted) {
                lret = ttm_bo_wait_ctx(bo, walk->arg.ctx);
                if (!lret)
                        ttm_bo_cleanup_memtype_use(bo);
        } else {
                lret = ttm_bo_evict(bo, walk->arg.ctx);
        }

        if (lret)
                goto out;

        evict_walk->evicted++;
        if (evict_walk->res)
                lret = ttm_resource_alloc(evict_walk->evictor, evict_walk->place,
                                          evict_walk->res, NULL);
        if (lret == 0)
                return 1;
out:
        /* Errors that should terminate the walk. */
        if (lret == -ENOSPC)
                return -EBUSY;

        return lret;
}

static const struct ttm_lru_walk_ops ttm_evict_walk_ops = {
        .process_bo = ttm_bo_evict_cb,
};

static int ttm_bo_evict_alloc(struct ttm_device *bdev,
                              struct ttm_resource_manager *man,
                              const struct ttm_place *place,
                              struct ttm_buffer_object *evictor,
                              struct ttm_operation_ctx *ctx,
                              struct ww_acquire_ctx *ticket,
                              struct ttm_resource **res,
                              struct dmem_cgroup_pool_state *limit_pool)
{
        struct ttm_bo_evict_walk evict_walk = {
                .walk = {
                        .ops = &ttm_evict_walk_ops,
                        .arg = {
                                .ctx = ctx,
                                .ticket = ticket,
                        }
                },
                .place = place,
                .evictor = evictor,
                .res = res,
                .limit_pool = limit_pool,
        };
        s64 lret;

        evict_walk.walk.arg.trylock_only = true;
        lret = ttm_lru_walk_for_evict(&evict_walk.walk, bdev, man, 1);

        /* One more attempt if we hit low limit? */
        if (!lret && evict_walk.hit_low) {
                evict_walk.try_low = true;
                lret = ttm_lru_walk_for_evict(&evict_walk.walk, bdev, man, 1);
        }
        if (lret || !ticket)
                goto out;

        /* Reset low limit */
        evict_walk.try_low = evict_walk.hit_low = false;
        /* If ticket-locking, repeat while making progress. */
        evict_walk.walk.arg.trylock_only = false;

retry:
        do {
                /* The walk may clear the evict_walk.walk.ticket field */
                evict_walk.walk.arg.ticket = ticket;
                evict_walk.evicted = 0;
                lret = ttm_lru_walk_for_evict(&evict_walk.walk, bdev, man, 1);
        } while (!lret && evict_walk.evicted);

        /* We hit the low limit? Try once more */
        if (!lret && evict_walk.hit_low && !evict_walk.try_low) {
                evict_walk.try_low = true;
                goto retry;
        }
out:
        if (lret < 0)
                return lret;
        if (lret == 0)
                return -EBUSY;
        return 0;
}

/**
 * ttm_bo_pin - Pin the buffer object.
 * @bo: The buffer object to pin
 *
 * Make sure the buffer is not evicted any more during memory pressure.
 * @bo must be unpinned again by calling ttm_bo_unpin().
 */
void ttm_bo_pin(struct ttm_buffer_object *bo)
{
        dma_resv_assert_held(bo->base.resv);
        WARN_ON_ONCE(!kref_read(&bo->kref));
        spin_lock(&bo->bdev->lru_lock);
        if (bo->resource)
                ttm_resource_del_bulk_move(bo->resource, bo);
        if (!bo->pin_count++ && bo->resource)
                ttm_resource_move_to_lru_tail(bo->resource);
        spin_unlock(&bo->bdev->lru_lock);
}
EXPORT_SYMBOL(ttm_bo_pin);

/**
 * ttm_bo_unpin - Unpin the buffer object.
 * @bo: The buffer object to unpin
 *
 * Allows the buffer object to be evicted again during memory pressure.
 */
void ttm_bo_unpin(struct ttm_buffer_object *bo)
{
        dma_resv_assert_held(bo->base.resv);
        WARN_ON_ONCE(!kref_read(&bo->kref));
        if (WARN_ON_ONCE(!bo->pin_count))
                return;

        spin_lock(&bo->bdev->lru_lock);
        if (!--bo->pin_count && bo->resource) {
                ttm_resource_add_bulk_move(bo->resource, bo);
                ttm_resource_move_to_lru_tail(bo->resource);
        }
        spin_unlock(&bo->bdev->lru_lock);
}
EXPORT_SYMBOL(ttm_bo_unpin);

/*
 * Add the pipelined eviction fencesto the BO as kernel dependency and reserve new
 * fence slots.
 */
static int ttm_bo_add_pipelined_eviction_fences(struct ttm_buffer_object *bo,
                                                struct ttm_resource_manager *man,
                                                bool no_wait_gpu)
{
        struct dma_fence *fence;
        int i;

        spin_lock(&man->eviction_lock);
        for (i = 0; i < TTM_NUM_MOVE_FENCES; i++) {
                fence = man->eviction_fences[i];
                if (!fence)
                        continue;

                if (no_wait_gpu) {
                        if (!dma_fence_is_signaled(fence)) {
                                spin_unlock(&man->eviction_lock);
                                return -EBUSY;
                        }
                } else {
                        dma_resv_add_fence(bo->base.resv, fence, DMA_RESV_USAGE_KERNEL);
                }
        }
        spin_unlock(&man->eviction_lock);

        /* TODO: this call should be removed. */
        return dma_resv_reserve_fences(bo->base.resv, 1);
}

/**
 * ttm_bo_alloc_resource - Allocate backing store for a BO
 *
 * @bo: Pointer to a struct ttm_buffer_object of which we want a resource for
 * @placement: Proposed new placement for the buffer object
 * @ctx: if and how to sleep, lock buffers and alloc memory
 * @force_space: If we should evict buffers to force space
 * @res: The resulting struct ttm_resource.
 *
 * Allocates a resource for the buffer object pointed to by @bo, using the
 * placement flags in @placement, potentially evicting other buffer objects when
 * @force_space is true.
 * This function may sleep while waiting for resources to become available.
 * Returns:
 * -EBUSY: No space available (only if no_wait == true).
 * -ENOSPC: Could not allocate space for the buffer object, either due to
 * fragmentation or concurrent allocators.
 * -ERESTARTSYS: An interruptible sleep was interrupted by a signal.
 */
static int ttm_bo_alloc_resource(struct ttm_buffer_object *bo,
                                 struct ttm_placement *placement,
                                 struct ttm_operation_ctx *ctx,
                                 bool force_space,
                                 struct ttm_resource **res)
{
        struct ttm_device *bdev = bo->bdev;
        struct ww_acquire_ctx *ticket;
        int i, ret;

        ticket = dma_resv_locking_ctx(bo->base.resv);
        ret = dma_resv_reserve_fences(bo->base.resv, TTM_NUM_MOVE_FENCES);
        if (unlikely(ret))
                return ret;

        for (i = 0; i < placement->num_placement; ++i) {
                const struct ttm_place *place = &placement->placement[i];
                struct dmem_cgroup_pool_state *limit_pool = NULL;
                struct ttm_resource_manager *man;
                bool may_evict;

                man = ttm_manager_type(bdev, place->mem_type);
                if (!man || !ttm_resource_manager_used(man))
                        continue;

                if (place->flags & (force_space ? TTM_PL_FLAG_DESIRED :
                                    TTM_PL_FLAG_FALLBACK))
                        continue;

                may_evict = (force_space && place->mem_type != TTM_PL_SYSTEM);
                ret = ttm_resource_alloc(bo, place, res, force_space ? &limit_pool : NULL);
                if (ret) {
                        if (ret != -ENOSPC && ret != -EAGAIN) {
                                dmem_cgroup_pool_state_put(limit_pool);
                                return ret;
                        }
                        if (!may_evict) {
                                dmem_cgroup_pool_state_put(limit_pool);
                                continue;
                        }

                        ret = ttm_bo_evict_alloc(bdev, man, place, bo, ctx,
                                                 ticket, res, limit_pool);
                        dmem_cgroup_pool_state_put(limit_pool);
                        if (ret == -EBUSY)
                                continue;
                        if (ret)
                                return ret;
                }

                ret = ttm_bo_add_pipelined_eviction_fences(bo, man, ctx->no_wait_gpu);
                if (unlikely(ret)) {
                        ttm_resource_free(bo, res);
                        if (ret == -EBUSY)
                                continue;

                        return ret;
                }
                return 0;
        }

        return -ENOSPC;
}

/*
 * ttm_bo_mem_space - Wrapper around ttm_bo_alloc_resource
 *
 * @bo: Pointer to a struct ttm_buffer_object of which we want a resource for
 * @placement: Proposed new placement for the buffer object
 * @res: The resulting struct ttm_resource.
 * @ctx: if and how to sleep, lock buffers and alloc memory
 *
 * Tries both idle allocation and forcefully eviction of buffers. See
 * ttm_bo_alloc_resource for details.
 */
int ttm_bo_mem_space(struct ttm_buffer_object *bo,
                     struct ttm_placement *placement,
                     struct ttm_resource **res,
                     struct ttm_operation_ctx *ctx)
{
        bool force_space = false;
        int ret;

        do {
                ret = ttm_bo_alloc_resource(bo, placement, ctx,
                                            force_space, res);
                force_space = !force_space;
        } while (ret == -ENOSPC && force_space);

        return ret;
}
EXPORT_SYMBOL(ttm_bo_mem_space);

/**
 * ttm_bo_validate
 *
 * @bo: The buffer object.
 * @placement: Proposed placement for the buffer object.
 * @ctx: validation parameters.
 *
 * Changes placement and caching policy of the buffer object
 * according proposed placement.
 * Returns
 * -EINVAL on invalid proposed placement.
 * -ENOMEM on out-of-memory condition.
 * -EBUSY if no_wait is true and buffer busy.
 * -ERESTARTSYS if interrupted by a signal.
 */
int ttm_bo_validate(struct ttm_buffer_object *bo,
                    struct ttm_placement *placement,
                    struct ttm_operation_ctx *ctx)
{
        struct ttm_resource *res;
        struct ttm_place hop;
        bool force_space;
        int ret;

        dma_resv_assert_held(bo->base.resv);

        /*
         * Remove the backing store if no placement is given.
         */
        if (!placement->num_placement)
                return ttm_bo_pipeline_gutting(bo);

        force_space = false;
        do {
                /* Check whether we need to move buffer. */
                if (bo->resource &&
                    ttm_resource_compatible(bo->resource, placement,
                                            force_space))
                        return 0;

                /* Moving of pinned BOs is forbidden */
                if (bo->pin_count)
                        return -EINVAL;

                /*
                 * Determine where to move the buffer.
                 *
                 * If driver determines move is going to need
                 * an extra step then it will return -EMULTIHOP
                 * and the buffer will be moved to the temporary
                 * stop and the driver will be called to make
                 * the second hop.
                 */
                ret = ttm_bo_alloc_resource(bo, placement, ctx, force_space,
                                            &res);
                force_space = !force_space;
                if (ret == -ENOSPC)
                        continue;
                if (ret)
                        return ret;

bounce:
                ret = ttm_bo_handle_move_mem(bo, res, false, ctx, &hop);
                if (ret == -EMULTIHOP) {
                        ret = ttm_bo_bounce_temp_buffer(bo, ctx, &hop);
                        /* try and move to final place now. */
                        if (!ret)
                                goto bounce;
                }
                if (ret) {
                        ttm_resource_free(bo, &res);
                        return ret;
                }

        } while (ret && force_space);

        /* For backward compatibility with userspace */
        if (ret == -ENOSPC)
                return bo->bdev->alloc_flags & TTM_ALLOCATION_PROPAGATE_ENOSPC ?
                       ret : -ENOMEM;

        /*
         * We might need to add a TTM.
         */
        if (!bo->resource || bo->resource->mem_type == TTM_PL_SYSTEM) {
                ret = ttm_tt_create(bo, true);
                if (ret)
                        return ret;
        }
        return 0;
}
EXPORT_SYMBOL(ttm_bo_validate);

/**
 * ttm_bo_init_reserved
 *
 * @bdev: Pointer to a ttm_device struct.
 * @bo: Pointer to a ttm_buffer_object to be initialized.
 * @type: Requested type of buffer object.
 * @placement: Initial placement for buffer object.
 * @alignment: Data alignment in pages.
 * @ctx: TTM operation context for memory allocation.
 * @sg: Scatter-gather table.
 * @resv: Pointer to a dma_resv, or NULL to let ttm allocate one.
 * @destroy: Destroy function. Use NULL for kfree().
 *
 * This function initializes a pre-allocated struct ttm_buffer_object.
 * As this object may be part of a larger structure, this function,
 * together with the @destroy function, enables driver-specific objects
 * derived from a ttm_buffer_object.
 *
 * On successful return, the caller owns an object kref to @bo. The kref and
 * list_kref are usually set to 1, but note that in some situations, other
 * tasks may already be holding references to @bo as well.
 * Furthermore, if resv == NULL, the buffer's reservation lock will be held,
 * and it is the caller's responsibility to call ttm_bo_unreserve.
 *
 * If a failure occurs, the function will call the @destroy function. Thus,
 * after a failure, dereferencing @bo is illegal and will likely cause memory
 * corruption.
 *
 * Returns
 * -ENOMEM: Out of memory.
 * -EINVAL: Invalid placement flags.
 * -ERESTARTSYS: Interrupted by signal while sleeping waiting for resources.
 */
int ttm_bo_init_reserved(struct ttm_device *bdev, struct ttm_buffer_object *bo,
                         enum ttm_bo_type type, struct ttm_placement *placement,
                         uint32_t alignment, struct ttm_operation_ctx *ctx,
                         struct sg_table *sg, struct dma_resv *resv,
                         void (*destroy) (struct ttm_buffer_object *))
{
        int ret;

        kref_init(&bo->kref);
        bo->bdev = bdev;
        bo->type = type;
        bo->page_alignment = alignment;
        bo->destroy = destroy;
        bo->pin_count = 0;
        bo->sg = sg;
        bo->bulk_move = NULL;
        if (resv)
                bo->base.resv = resv;
        else
                bo->base.resv = &bo->base._resv;
        atomic_inc(&ttm_glob.bo_count);

        /*
         * For ttm_bo_type_device buffers, allocate
         * address space from the device.
         */
        if (bo->type == ttm_bo_type_device || bo->type == ttm_bo_type_sg) {
                ret = drm_vma_offset_add(bdev->vma_manager, &bo->base.vma_node,
                                         PFN_UP(bo->base.size));
                if (ret)
                        goto err_put;
        }

        /* passed reservation objects should already be locked,
         * since otherwise lockdep will be angered in radeon.
         */
        if (!resv)
                WARN_ON(!dma_resv_trylock(bo->base.resv));
        else
                dma_resv_assert_held(resv);

        ret = ttm_bo_validate(bo, placement, ctx);
        if (unlikely(ret))
                goto err_unlock;

        return 0;

err_unlock:
        if (!resv)
                dma_resv_unlock(bo->base.resv);

err_put:
        ttm_bo_put(bo);
        return ret;
}
EXPORT_SYMBOL(ttm_bo_init_reserved);

/**
 * ttm_bo_init_validate
 *
 * @bdev: Pointer to a ttm_device struct.
 * @bo: Pointer to a ttm_buffer_object to be initialized.
 * @type: Requested type of buffer object.
 * @placement: Initial placement for buffer object.
 * @alignment: Data alignment in pages.
 * @interruptible: If needing to sleep to wait for GPU resources,
 * sleep interruptible.
 * pinned in physical memory. If this behaviour is not desired, this member
 * holds a pointer to a persistent shmem object. Typically, this would
 * point to the shmem object backing a GEM object if TTM is used to back a
 * GEM user interface.
 * @sg: Scatter-gather table.
 * @resv: Pointer to a dma_resv, or NULL to let ttm allocate one.
 * @destroy: Destroy function. Use NULL for kfree().
 *
 * This function initializes a pre-allocated struct ttm_buffer_object.
 * As this object may be part of a larger structure, this function,
 * together with the @destroy function,
 * enables driver-specific objects derived from a ttm_buffer_object.
 *
 * On successful return, the caller owns an object kref to @bo. The kref and
 * list_kref are usually set to 1, but note that in some situations, other
 * tasks may already be holding references to @bo as well.
 *
 * If a failure occurs, the function will call the @destroy function, Thus,
 * after a failure, dereferencing @bo is illegal and will likely cause memory
 * corruption.
 *
 * Returns
 * -ENOMEM: Out of memory.
 * -EINVAL: Invalid placement flags.
 * -ERESTARTSYS: Interrupted by signal while sleeping waiting for resources.
 */
int ttm_bo_init_validate(struct ttm_device *bdev, struct ttm_buffer_object *bo,
                         enum ttm_bo_type type, struct ttm_placement *placement,
                         uint32_t alignment, bool interruptible,
                         struct sg_table *sg, struct dma_resv *resv,
                         void (*destroy) (struct ttm_buffer_object *))
{
        struct ttm_operation_ctx ctx = { .interruptible = interruptible };
        int ret;

        ret = ttm_bo_init_reserved(bdev, bo, type, placement, alignment, &ctx,
                                   sg, resv, destroy);
        if (ret)
                return ret;

        if (!resv)
                ttm_bo_unreserve(bo);

        return 0;
}
EXPORT_SYMBOL(ttm_bo_init_validate);

/*
 * buffer object vm functions.
 */

/**
 * ttm_bo_unmap_virtual
 *
 * @bo: tear down the virtual mappings for this BO
 */
void ttm_bo_unmap_virtual(struct ttm_buffer_object *bo)
{
        struct ttm_device *bdev = bo->bdev;

        drm_vma_node_unmap(&bo->base.vma_node, bdev->dev_mapping);
        ttm_mem_io_free(bdev, bo->resource);
}
EXPORT_SYMBOL(ttm_bo_unmap_virtual);

/**
 * ttm_bo_wait_ctx - wait for buffer idle.
 *
 * @bo:  The buffer object.
 * @ctx: defines how to wait
 *
 * Waits for the buffer to be idle. Used timeout depends on the context.
 * Returns -EBUSY if wait timed outt, -ERESTARTSYS if interrupted by a signal or
 * zero on success.
 */
int ttm_bo_wait_ctx(struct ttm_buffer_object *bo, struct ttm_operation_ctx *ctx)
{
        long ret;

        if (ctx->no_wait_gpu) {
                if (dma_resv_test_signaled(bo->base.resv,
                                           DMA_RESV_USAGE_BOOKKEEP))
                        return 0;
                else
                        return -EBUSY;
        }

        ret = dma_resv_wait_timeout(bo->base.resv, DMA_RESV_USAGE_BOOKKEEP,
                                    ctx->interruptible, 15 * HZ);
        if (unlikely(ret < 0))
                return ret;
        if (unlikely(ret == 0))
                return -EBUSY;
        return 0;
}
EXPORT_SYMBOL(ttm_bo_wait_ctx);

/**
 * struct ttm_bo_swapout_walk - Parameters for the swapout walk
 */
struct ttm_bo_swapout_walk {
        /** @walk: The walk base parameters. */
        struct ttm_lru_walk walk;
        /** @gfp_flags: The gfp flags to use for ttm_tt_swapout() */
        gfp_t gfp_flags;
        /** @hit_low: Whether we should attempt to swap BO's with low watermark threshold */
        /** @evict_low: If we cannot swap a bo when @try_low is false (first pass) */
        bool hit_low, evict_low;
};

static s64
ttm_bo_swapout_cb(struct ttm_lru_walk *walk, struct ttm_buffer_object *bo)
{
        struct ttm_place place = { .mem_type = bo->resource->mem_type };
        struct ttm_bo_swapout_walk *swapout_walk =
                container_of(walk, typeof(*swapout_walk), walk);
        struct ttm_operation_ctx *ctx = walk->arg.ctx;
        struct ttm_device *bdev = bo->bdev;
        struct ttm_tt *tt = bo->ttm;
        s64 ret;

        /*
         * While the bo may already reside in SYSTEM placement, set
         * SYSTEM as new placement to cover also the move further below.
         * The driver may use the fact that we're moving from SYSTEM
         * as an indication that we're about to swap out.
         */
        if (bo->pin_count || !bdev->funcs->eviction_valuable(bo, &place)) {
                ret = -EBUSY;
                goto out;
        }

        if (!tt || !ttm_tt_is_populated(tt) ||
            tt->page_flags & (TTM_TT_FLAG_EXTERNAL | TTM_TT_FLAG_SWAPPED)) {
                ret = -EBUSY;
                goto out;
        }

        if (bo->deleted) {
                pgoff_t num_pages = tt->num_pages;

                ret = ttm_bo_wait_ctx(bo, ctx);
                if (ret)
                        goto out;

                ttm_bo_cleanup_memtype_use(bo);
                ret = num_pages;
                goto out;
        }

        /*
         * Move to system cached
         */
        if (bo->resource->mem_type != TTM_PL_SYSTEM) {
                struct ttm_resource *evict_mem;
                struct ttm_place hop;

                memset(&hop, 0, sizeof(hop));
                place.mem_type = TTM_PL_SYSTEM;
                ret = ttm_resource_alloc(bo, &place, &evict_mem, NULL);
                if (ret)
                        goto out;

                ret = ttm_bo_handle_move_mem(bo, evict_mem, true, ctx, &hop);
                if (ret) {
                        WARN(ret == -EMULTIHOP,
                             "Unexpected multihop in swapout - likely driver bug.\n");
                        ttm_resource_free(bo, &evict_mem);
                        goto out;
                }
        }

        /*
         * Make sure BO is idle.
         */
        ret = ttm_bo_wait_ctx(bo, ctx);
        if (ret)
                goto out;

        ttm_bo_unmap_virtual(bo);
        if (bdev->funcs->swap_notify)
                bdev->funcs->swap_notify(bo);

        if (ttm_tt_is_populated(tt)) {
                spin_lock(&bdev->lru_lock);
                ttm_resource_del_bulk_move(bo->resource, bo);
                spin_unlock(&bdev->lru_lock);

                ret = ttm_tt_swapout(bdev, tt, swapout_walk->gfp_flags);

                spin_lock(&bdev->lru_lock);
                if (ret)
                        ttm_resource_add_bulk_move(bo->resource, bo);
                ttm_resource_move_to_lru_tail(bo->resource);
                spin_unlock(&bdev->lru_lock);
        }

out:
        /* Consider -ENOMEM and -ENOSPC non-fatal. */
        if (ret == -ENOMEM || ret == -ENOSPC)
                ret = -EBUSY;

        return ret;
}

const struct ttm_lru_walk_ops ttm_swap_ops = {
        .process_bo = ttm_bo_swapout_cb,
};

/**
 * ttm_bo_swapout() - Swap out buffer objects on the LRU list to shmem.
 * @bdev: The ttm device.
 * @ctx: The ttm_operation_ctx governing the swapout operation.
 * @man: The resource manager whose resources / buffer objects are
 * goint to be swapped out.
 * @gfp_flags: The gfp flags used for shmem page allocations.
 * @target: The desired number of bytes to swap out.
 *
 * Return: The number of bytes actually swapped out, or negative error code
 * on error.
 */
s64 ttm_bo_swapout(struct ttm_device *bdev, struct ttm_operation_ctx *ctx,
                   struct ttm_resource_manager *man, gfp_t gfp_flags,
                   s64 target)
{
        struct ttm_bo_swapout_walk swapout_walk = {
                .walk = {
                        .ops = &ttm_swap_ops,
                        .arg = {
                                .ctx = ctx,
                                .trylock_only = true,
                        },
                },
                .gfp_flags = gfp_flags,
        };

        return ttm_lru_walk_for_evict(&swapout_walk.walk, bdev, man, target);
}

void ttm_bo_tt_destroy(struct ttm_buffer_object *bo)
{
        if (bo->ttm == NULL)
                return;

        ttm_tt_unpopulate(bo->bdev, bo->ttm);
        ttm_tt_destroy(bo->bdev, bo->ttm);
        bo->ttm = NULL;
}

/**
 * ttm_bo_populate() - Ensure that a buffer object has backing pages
 * @bo: The buffer object
 * @ctx: The ttm_operation_ctx governing the operation.
 *
 * For buffer objects in a memory type whose manager uses
 * struct ttm_tt for backing pages, ensure those backing pages
 * are present and with valid content. The bo's resource is also
 * placed on the correct LRU list if it was previously swapped
 * out.
 *
 * Return: 0 if successful, negative error code on failure.
 * Note: May return -EINTR or -ERESTARTSYS if @ctx::interruptible
 * is set to true.
 */
int ttm_bo_populate(struct ttm_buffer_object *bo,
                    struct ttm_operation_ctx *ctx)
{
        struct ttm_device *bdev = bo->bdev;
        struct ttm_tt *tt = bo->ttm;
        bool swapped;
        int ret;

        dma_resv_assert_held(bo->base.resv);

        if (!tt)
                return 0;

        swapped = ttm_tt_is_swapped(tt);
        ret = ttm_tt_populate(bdev, tt, ctx);
        if (ret)
                return ret;

        if (swapped && !ttm_tt_is_swapped(tt) && !bo->pin_count &&
            bo->resource) {
                spin_lock(&bdev->lru_lock);
                ttm_resource_add_bulk_move(bo->resource, bo);
                ttm_resource_move_to_lru_tail(bo->resource);
                spin_unlock(&bdev->lru_lock);
        }

        return 0;
}
EXPORT_SYMBOL(ttm_bo_populate);

int ttm_bo_setup_export(struct ttm_buffer_object *bo,
                        struct ttm_operation_ctx *ctx)
{
        int ret;

        ret = ttm_bo_reserve(bo, false, false, NULL);
        if (ret != 0)
                return ret;

        ret = ttm_bo_populate(bo, ctx);
        ttm_bo_unreserve(bo);
        return ret;
}
EXPORT_SYMBOL(ttm_bo_setup_export);