/* SPDX-License-Identifier: GPL-2.0 OR MIT */
/**************************************************************************
 *
 * Copyright (c) 2007-2009 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>
 */

#include <drm/ttm/ttm_bo_driver.h>
#include <drm/ttm/ttm_placement.h>
#include <drm/drm_vma_manager.h>
#include <linux/io.h>
#include <linux/highmem.h>
#include <linux/wait.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/module.h>
#include <linux/dma-resv.h>

struct ttm_transfer_obj {
        struct ttm_buffer_object base;
        struct ttm_buffer_object *bo;
};

void ttm_bo_free_old_node(struct ttm_buffer_object *bo)
{
        ttm_bo_mem_put(bo, &bo->mem);
}

int ttm_bo_move_ttm(struct ttm_buffer_object *bo,
                   struct ttm_operation_ctx *ctx,
                    struct ttm_mem_reg *new_mem)
{
        struct ttm_tt *ttm = bo->ttm;
        struct ttm_mem_reg *old_mem = &bo->mem;
        int ret;

        if (old_mem->mem_type != TTM_PL_SYSTEM) {
                ret = ttm_bo_wait(bo, ctx->interruptible, ctx->no_wait_gpu);

                if (unlikely(ret != 0)) {
                        if (ret != -ERESTARTSYS)
                                pr_err("Failed to expire sync object before unbinding TTM\n");
                        return ret;
                }

                ttm_tt_unbind(ttm);
                ttm_bo_free_old_node(bo);
                ttm_flag_masked(&old_mem->placement, TTM_PL_FLAG_SYSTEM,
                                TTM_PL_MASK_MEM);
                old_mem->mem_type = TTM_PL_SYSTEM;
        }

        ret = ttm_tt_set_placement_caching(ttm, new_mem->placement);
        if (unlikely(ret != 0))
                return ret;

        if (new_mem->mem_type != TTM_PL_SYSTEM) {
                ret = ttm_tt_bind(ttm, new_mem, ctx);
                if (unlikely(ret != 0))
                        return ret;
        }

        *old_mem = *new_mem;
        new_mem->mm_node = NULL;

        return 0;
}
EXPORT_SYMBOL(ttm_bo_move_ttm);

int ttm_mem_io_lock(struct ttm_mem_type_manager *man, bool interruptible)
{
        if (likely(man->io_reserve_fastpath))
                return 0;

        if (interruptible)
                return mutex_lock_interruptible(&man->io_reserve_mutex);

        mutex_lock(&man->io_reserve_mutex);
        return 0;
}

void ttm_mem_io_unlock(struct ttm_mem_type_manager *man)
{
        if (likely(man->io_reserve_fastpath))
                return;

        mutex_unlock(&man->io_reserve_mutex);
}

static int ttm_mem_io_evict(struct ttm_mem_type_manager *man)
{
        struct ttm_buffer_object *bo;

        if (!man->use_io_reserve_lru || list_empty(&man->io_reserve_lru))
                return -EAGAIN;

        bo = list_first_entry(&man->io_reserve_lru,
                              struct ttm_buffer_object,
                              io_reserve_lru);
        list_del_init(&bo->io_reserve_lru);
        ttm_bo_unmap_virtual_locked(bo);

        return 0;
}


int ttm_mem_io_reserve(struct ttm_bo_device *bdev,
                       struct ttm_mem_reg *mem)
{
        struct ttm_mem_type_manager *man = &bdev->man[mem->mem_type];
        int ret = 0;

        if (!bdev->driver->io_mem_reserve)
                return 0;
        if (likely(man->io_reserve_fastpath))
                return bdev->driver->io_mem_reserve(bdev, mem);

        if (bdev->driver->io_mem_reserve &&
            mem->bus.io_reserved_count++ == 0) {
retry:
                ret = bdev->driver->io_mem_reserve(bdev, mem);
                if (ret == -EAGAIN) {
                        ret = ttm_mem_io_evict(man);
                        if (ret == 0)
                                goto retry;
                }
        }
        return ret;
}

void ttm_mem_io_free(struct ttm_bo_device *bdev,
                     struct ttm_mem_reg *mem)
{
        struct ttm_mem_type_manager *man = &bdev->man[mem->mem_type];

        if (likely(man->io_reserve_fastpath))
                return;

        if (bdev->driver->io_mem_reserve &&
            --mem->bus.io_reserved_count == 0 &&
            bdev->driver->io_mem_free)
                bdev->driver->io_mem_free(bdev, mem);

}

int ttm_mem_io_reserve_vm(struct ttm_buffer_object *bo)
{
        struct ttm_mem_reg *mem = &bo->mem;
        int ret;

        if (!mem->bus.io_reserved_vm) {
                struct ttm_mem_type_manager *man =
                        &bo->bdev->man[mem->mem_type];

                ret = ttm_mem_io_reserve(bo->bdev, mem);
                if (unlikely(ret != 0))
                        return ret;
                mem->bus.io_reserved_vm = true;
                if (man->use_io_reserve_lru)
                        list_add_tail(&bo->io_reserve_lru,
                                      &man->io_reserve_lru);
        }
        return 0;
}

void ttm_mem_io_free_vm(struct ttm_buffer_object *bo)
{
        struct ttm_mem_reg *mem = &bo->mem;

        if (mem->bus.io_reserved_vm) {
                mem->bus.io_reserved_vm = false;
                list_del_init(&bo->io_reserve_lru);
                ttm_mem_io_free(bo->bdev, mem);
        }
}

static int ttm_mem_reg_ioremap(struct ttm_bo_device *bdev, struct ttm_mem_reg *mem,
                        void **virtual)
{
        struct ttm_mem_type_manager *man = &bdev->man[mem->mem_type];
        int ret;
        void *addr;

        *virtual = NULL;
        (void) ttm_mem_io_lock(man, false);
        ret = ttm_mem_io_reserve(bdev, mem);
        ttm_mem_io_unlock(man);
        if (ret || !mem->bus.is_iomem)
                return ret;

        if (mem->bus.addr) {
                addr = mem->bus.addr;
        } else {
                if (mem->placement & TTM_PL_FLAG_WC)
                        addr = ioremap_wc(mem->bus.base + mem->bus.offset, mem->bus.size);
                else
                        addr = ioremap(mem->bus.base + mem->bus.offset, mem->bus.size);
                if (!addr) {
                        (void) ttm_mem_io_lock(man, false);
                        ttm_mem_io_free(bdev, mem);
                        ttm_mem_io_unlock(man);
                        return -ENOMEM;
                }
        }
        *virtual = addr;
        return 0;
}

static void ttm_mem_reg_iounmap(struct ttm_bo_device *bdev, struct ttm_mem_reg *mem,
                         void *virtual)
{
        struct ttm_mem_type_manager *man;

        man = &bdev->man[mem->mem_type];

        if (virtual && mem->bus.addr == NULL)
                iounmap(virtual);
        (void) ttm_mem_io_lock(man, false);
        ttm_mem_io_free(bdev, mem);
        ttm_mem_io_unlock(man);
}

static int ttm_copy_io_page(void *dst, void *src, unsigned long page)
{
        uint32_t *dstP =
            (uint32_t *) ((unsigned long)dst + (page << PAGE_SHIFT));
        uint32_t *srcP =
            (uint32_t *) ((unsigned long)src + (page << PAGE_SHIFT));

        int i;
        for (i = 0; i < PAGE_SIZE / sizeof(uint32_t); ++i)
                iowrite32(ioread32(srcP++), dstP++);
        return 0;
}

static int ttm_copy_io_ttm_page(struct ttm_tt *ttm, void *src,
                                unsigned long page,
                                pgprot_t prot)
{
        struct page *d = ttm->pages[page];
        void *dst;

        if (!d)
                return -ENOMEM;

        src = (void *)((unsigned long)src + (page << PAGE_SHIFT));
        dst = kmap_atomic_prot(d, prot);
        if (!dst)
                return -ENOMEM;

        memcpy_fromio(dst, src, PAGE_SIZE);

        kunmap_atomic(dst);

        return 0;
}

static int ttm_copy_ttm_io_page(struct ttm_tt *ttm, void *dst,
                                unsigned long page,
                                pgprot_t prot)
{
        struct page *s = ttm->pages[page];
        void *src;

        if (!s)
                return -ENOMEM;

        dst = (void *)((unsigned long)dst + (page << PAGE_SHIFT));
        src = kmap_atomic_prot(s, prot);
        if (!src)
                return -ENOMEM;

        memcpy_toio(dst, src, PAGE_SIZE);

        kunmap_atomic(src);

        return 0;
}

int ttm_bo_move_memcpy(struct ttm_buffer_object *bo,
                       struct ttm_operation_ctx *ctx,
                       struct ttm_mem_reg *new_mem)
{
        struct ttm_bo_device *bdev = bo->bdev;
        struct ttm_mem_type_manager *man = &bdev->man[new_mem->mem_type];
        struct ttm_tt *ttm = bo->ttm;
        struct ttm_mem_reg *old_mem = &bo->mem;
        struct ttm_mem_reg old_copy = *old_mem;
        void *old_iomap;
        void *new_iomap;
        int ret;
        unsigned long i;
        unsigned long page;
        unsigned long add = 0;
        int dir;

        ret = ttm_bo_wait(bo, ctx->interruptible, ctx->no_wait_gpu);
        if (ret)
                return ret;

        ret = ttm_mem_reg_ioremap(bdev, old_mem, &old_iomap);
        if (ret)
                return ret;
        ret = ttm_mem_reg_ioremap(bdev, new_mem, &new_iomap);
        if (ret)
                goto out;

        /*
         * Single TTM move. NOP.
         */
        if (old_iomap == NULL && new_iomap == NULL)
                goto out2;

        /*
         * Don't move nonexistent data. Clear destination instead.
         */
        if (old_iomap == NULL &&
            (ttm == NULL || (ttm->state == tt_unpopulated &&
                             !(ttm->page_flags & TTM_PAGE_FLAG_SWAPPED)))) {
                memset_io(new_iomap, 0, new_mem->num_pages*PAGE_SIZE);
                goto out2;
        }

        /*
         * TTM might be null for moves within the same region.
         */
        if (ttm) {
                ret = ttm_tt_populate(ttm, ctx);
                if (ret)
                        goto out1;
        }

        add = 0;
        dir = 1;

        if ((old_mem->mem_type == new_mem->mem_type) &&
            (new_mem->start < old_mem->start + old_mem->size)) {
                dir = -1;
                add = new_mem->num_pages - 1;
        }

        for (i = 0; i < new_mem->num_pages; ++i) {
                page = i * dir + add;
                if (old_iomap == NULL) {
                        pgprot_t prot = ttm_io_prot(old_mem->placement,
                                                    PAGE_KERNEL);
                        ret = ttm_copy_ttm_io_page(ttm, new_iomap, page,
                                                   prot);
                } else if (new_iomap == NULL) {
                        pgprot_t prot = ttm_io_prot(new_mem->placement,
                                                    PAGE_KERNEL);
                        ret = ttm_copy_io_ttm_page(ttm, old_iomap, page,
                                                   prot);
                } else {
                        ret = ttm_copy_io_page(new_iomap, old_iomap, page);
                }
                if (ret)
                        goto out1;
        }
        mb();
out2:
        old_copy = *old_mem;
        *old_mem = *new_mem;
        new_mem->mm_node = NULL;

        if (man->flags & TTM_MEMTYPE_FLAG_FIXED) {
                ttm_tt_destroy(ttm);
                bo->ttm = NULL;
        }

out1:
        ttm_mem_reg_iounmap(bdev, old_mem, new_iomap);
out:
        ttm_mem_reg_iounmap(bdev, &old_copy, old_iomap);

        /*
         * On error, keep the mm node!
         */
        if (!ret)
                ttm_bo_mem_put(bo, &old_copy);
        return ret;
}
EXPORT_SYMBOL(ttm_bo_move_memcpy);

static void ttm_transfered_destroy(struct ttm_buffer_object *bo)
{
        struct ttm_transfer_obj *fbo;

        fbo = container_of(bo, struct ttm_transfer_obj, base);
        ttm_bo_put(fbo->bo);
        kfree(fbo);
}

/**
 * ttm_buffer_object_transfer
 *
 * @bo: A pointer to a struct ttm_buffer_object.
 * @new_obj: A pointer to a pointer to a newly created ttm_buffer_object,
 * holding the data of @bo with the old placement.
 *
 * This is a utility function that may be called after an accelerated move
 * has been scheduled. A new buffer object is created as a placeholder for
 * the old data while it's being copied. When that buffer object is idle,
 * it can be destroyed, releasing the space of the old placement.
 * Returns:
 * !0: Failure.
 */

static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo,
                                      struct ttm_buffer_object **new_obj)
{
        struct ttm_transfer_obj *fbo;
        int ret;

        fbo = kmalloc(sizeof(*fbo), GFP_KERNEL);
        if (!fbo)
                return -ENOMEM;

        fbo->base = *bo;
        fbo->base.mem.placement |= TTM_PL_FLAG_NO_EVICT;

        ttm_bo_get(bo);
        fbo->bo = bo;

        /**
         * Fix up members that we shouldn't copy directly:
         * TODO: Explicit member copy would probably be better here.
         */

        atomic_inc(&ttm_bo_glob.bo_count);
        INIT_LIST_HEAD(&fbo->base.ddestroy);
        INIT_LIST_HEAD(&fbo->base.lru);
        INIT_LIST_HEAD(&fbo->base.swap);
        INIT_LIST_HEAD(&fbo->base.io_reserve_lru);
        fbo->base.moving = NULL;
        drm_vma_node_reset(&fbo->base.base.vma_node);

        kref_init(&fbo->base.kref);
        fbo->base.destroy = &ttm_transfered_destroy;
        fbo->base.acc_size = 0;
        if (bo->type != ttm_bo_type_sg)
                fbo->base.base.resv = &fbo->base.base._resv;

        dma_resv_init(&fbo->base.base._resv);
        fbo->base.base.dev = NULL;
        ret = dma_resv_trylock(&fbo->base.base._resv);
        WARN_ON(!ret);

        *new_obj = &fbo->base;
        return 0;
}

pgprot_t ttm_io_prot(uint32_t caching_flags, pgprot_t tmp)
{
        /* Cached mappings need no adjustment */
        if (caching_flags & TTM_PL_FLAG_CACHED)
                return tmp;

#if defined(__i386__) || defined(__x86_64__)
        if (caching_flags & TTM_PL_FLAG_WC)
                tmp = pgprot_writecombine(tmp);
        else if (boot_cpu_data.x86 > 3)
                tmp = pgprot_noncached(tmp);
#endif
#if defined(__ia64__) || defined(__arm__) || defined(__aarch64__) || \
    defined(__powerpc__) || defined(__mips__)
        if (caching_flags & TTM_PL_FLAG_WC)
                tmp = pgprot_writecombine(tmp);
        else
                tmp = pgprot_noncached(tmp);
#endif
#if defined(__sparc__)
        tmp = pgprot_noncached(tmp);
#endif
        return tmp;
}
EXPORT_SYMBOL(ttm_io_prot);

static int ttm_bo_ioremap(struct ttm_buffer_object *bo,
                          unsigned long offset,
                          unsigned long size,
                          struct ttm_bo_kmap_obj *map)
{
        struct ttm_mem_reg *mem = &bo->mem;

        if (bo->mem.bus.addr) {
                map->bo_kmap_type = ttm_bo_map_premapped;
                map->virtual = (void *)(((u8 *)bo->mem.bus.addr) + offset);
        } else {
                map->bo_kmap_type = ttm_bo_map_iomap;
                if (mem->placement & TTM_PL_FLAG_WC)
                        map->virtual = ioremap_wc(bo->mem.bus.base + bo->mem.bus.offset + offset,
                                                  size);
                else
                        map->virtual = ioremap(bo->mem.bus.base + bo->mem.bus.offset + offset,
                                                       size);
        }
        return (!map->virtual) ? -ENOMEM : 0;
}

static int ttm_bo_kmap_ttm(struct ttm_buffer_object *bo,
                           unsigned long start_page,
                           unsigned long num_pages,
                           struct ttm_bo_kmap_obj *map)
{
        struct ttm_mem_reg *mem = &bo->mem;
        struct ttm_operation_ctx ctx = {
                .interruptible = false,
                .no_wait_gpu = false
        };
        struct ttm_tt *ttm = bo->ttm;
        pgprot_t prot;
        int ret;

        BUG_ON(!ttm);

        ret = ttm_tt_populate(ttm, &ctx);
        if (ret)
                return ret;

        if (num_pages == 1 && (mem->placement & TTM_PL_FLAG_CACHED)) {
                /*
                 * We're mapping a single page, and the desired
                 * page protection is consistent with the bo.
                 */

                map->bo_kmap_type = ttm_bo_map_kmap;
                map->page = ttm->pages[start_page];
                map->virtual = kmap(map->page);
        } else {
                /*
                 * We need to use vmap to get the desired page protection
                 * or to make the buffer object look contiguous.
                 */
                prot = ttm_io_prot(mem->placement, PAGE_KERNEL);
                map->bo_kmap_type = ttm_bo_map_vmap;
                map->virtual = vmap(ttm->pages + start_page, num_pages,
                                    0, prot);
        }
        return (!map->virtual) ? -ENOMEM : 0;
}

int ttm_bo_kmap(struct ttm_buffer_object *bo,
                unsigned long start_page, unsigned long num_pages,
                struct ttm_bo_kmap_obj *map)
{
        struct ttm_mem_type_manager *man =
                &bo->bdev->man[bo->mem.mem_type];
        unsigned long offset, size;
        int ret;

        map->virtual = NULL;
        map->bo = bo;
        if (num_pages > bo->num_pages)
                return -EINVAL;
        if (start_page > bo->num_pages)
                return -EINVAL;

        (void) ttm_mem_io_lock(man, false);
        ret = ttm_mem_io_reserve(bo->bdev, &bo->mem);
        ttm_mem_io_unlock(man);
        if (ret)
                return ret;
        if (!bo->mem.bus.is_iomem) {
                return ttm_bo_kmap_ttm(bo, start_page, num_pages, map);
        } else {
                offset = start_page << PAGE_SHIFT;
                size = num_pages << PAGE_SHIFT;
                return ttm_bo_ioremap(bo, offset, size, map);
        }
}
EXPORT_SYMBOL(ttm_bo_kmap);

void ttm_bo_kunmap(struct ttm_bo_kmap_obj *map)
{
        struct ttm_buffer_object *bo = map->bo;
        struct ttm_mem_type_manager *man =
                &bo->bdev->man[bo->mem.mem_type];

        if (!map->virtual)
                return;
        switch (map->bo_kmap_type) {
        case ttm_bo_map_iomap:
                iounmap(map->virtual);
                break;
        case ttm_bo_map_vmap:
                vunmap(map->virtual);
                break;
        case ttm_bo_map_kmap:
                kunmap(map->page);
                break;
        case ttm_bo_map_premapped:
                break;
        default:
                BUG();
        }
        (void) ttm_mem_io_lock(man, false);
        ttm_mem_io_free(map->bo->bdev, &map->bo->mem);
        ttm_mem_io_unlock(man);
        map->virtual = NULL;
        map->page = NULL;
}
EXPORT_SYMBOL(ttm_bo_kunmap);

int ttm_bo_move_accel_cleanup(struct ttm_buffer_object *bo,
                              struct dma_fence *fence,
                              bool evict,
                              struct ttm_mem_reg *new_mem)
{
        struct ttm_bo_device *bdev = bo->bdev;
        struct ttm_mem_type_manager *man = &bdev->man[new_mem->mem_type];
        struct ttm_mem_reg *old_mem = &bo->mem;
        int ret;
        struct ttm_buffer_object *ghost_obj;

        dma_resv_add_excl_fence(bo->base.resv, fence);
        if (evict) {
                ret = ttm_bo_wait(bo, false, false);
                if (ret)
                        return ret;

                if (man->flags & TTM_MEMTYPE_FLAG_FIXED) {
                        ttm_tt_destroy(bo->ttm);
                        bo->ttm = NULL;
                }
                ttm_bo_free_old_node(bo);
        } else {
                /**
                 * This should help pipeline ordinary buffer moves.
                 *
                 * Hang old buffer memory on a new buffer object,
                 * and leave it to be released when the GPU
                 * operation has completed.
                 */

                dma_fence_put(bo->moving);
                bo->moving = dma_fence_get(fence);

                ret = ttm_buffer_object_transfer(bo, &ghost_obj);
                if (ret)
                        return ret;

                dma_resv_add_excl_fence(&ghost_obj->base._resv, fence);

                /**
                 * If we're not moving to fixed memory, the TTM object
                 * needs to stay alive. Otherwhise hang it on the ghost
                 * bo to be unbound and destroyed.
                 */

                if (!(man->flags & TTM_MEMTYPE_FLAG_FIXED))
                        ghost_obj->ttm = NULL;
                else
                        bo->ttm = NULL;

                dma_resv_unlock(&ghost_obj->base._resv);
                ttm_bo_put(ghost_obj);
        }

        *old_mem = *new_mem;
        new_mem->mm_node = NULL;

        return 0;
}
EXPORT_SYMBOL(ttm_bo_move_accel_cleanup);

int ttm_bo_pipeline_move(struct ttm_buffer_object *bo,
                         struct dma_fence *fence, bool evict,
                         struct ttm_mem_reg *new_mem)
{
        struct ttm_bo_device *bdev = bo->bdev;
        struct ttm_mem_reg *old_mem = &bo->mem;

        struct ttm_mem_type_manager *from = &bdev->man[old_mem->mem_type];
        struct ttm_mem_type_manager *to = &bdev->man[new_mem->mem_type];

        int ret;

        dma_resv_add_excl_fence(bo->base.resv, fence);

        if (!evict) {
                struct ttm_buffer_object *ghost_obj;

                /**
                 * This should help pipeline ordinary buffer moves.
                 *
                 * Hang old buffer memory on a new buffer object,
                 * and leave it to be released when the GPU
                 * operation has completed.
                 */

                dma_fence_put(bo->moving);
                bo->moving = dma_fence_get(fence);

                ret = ttm_buffer_object_transfer(bo, &ghost_obj);
                if (ret)
                        return ret;

                dma_resv_add_excl_fence(&ghost_obj->base._resv, fence);

                /**
                 * If we're not moving to fixed memory, the TTM object
                 * needs to stay alive. Otherwhise hang it on the ghost
                 * bo to be unbound and destroyed.
                 */

                if (!(to->flags & TTM_MEMTYPE_FLAG_FIXED))
                        ghost_obj->ttm = NULL;
                else
                        bo->ttm = NULL;

                dma_resv_unlock(&ghost_obj->base._resv);
                ttm_bo_put(ghost_obj);

        } else if (from->flags & TTM_MEMTYPE_FLAG_FIXED) {

                /**
                 * BO doesn't have a TTM we need to bind/unbind. Just remember
                 * this eviction and free up the allocation
                 */

                spin_lock(&from->move_lock);
                if (!from->move || dma_fence_is_later(fence, from->move)) {
                        dma_fence_put(from->move);
                        from->move = dma_fence_get(fence);
                }
                spin_unlock(&from->move_lock);

                ttm_bo_free_old_node(bo);

                dma_fence_put(bo->moving);
                bo->moving = dma_fence_get(fence);

        } else {
                /**
                 * Last resort, wait for the move to be completed.
                 *
                 * Should never happen in pratice.
                 */

                ret = ttm_bo_wait(bo, false, false);
                if (ret)
                        return ret;

                if (to->flags & TTM_MEMTYPE_FLAG_FIXED) {
                        ttm_tt_destroy(bo->ttm);
                        bo->ttm = NULL;
                }
                ttm_bo_free_old_node(bo);
        }

        *old_mem = *new_mem;
        new_mem->mm_node = NULL;

        return 0;
}
EXPORT_SYMBOL(ttm_bo_pipeline_move);

int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo)
{
        struct ttm_buffer_object *ghost;
        int ret;

        ret = ttm_buffer_object_transfer(bo, &ghost);
        if (ret)
                return ret;

        ret = dma_resv_copy_fences(&ghost->base._resv, bo->base.resv);
        /* Last resort, wait for the BO to be idle when we are OOM */
        if (ret)
                ttm_bo_wait(bo, false, false);

        memset(&bo->mem, 0, sizeof(bo->mem));
        bo->mem.mem_type = TTM_PL_SYSTEM;
        bo->ttm = NULL;

        dma_resv_unlock(&ghost->base._resv);
        ttm_bo_put(ghost);

        return 0;
}