/* 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 <linux/export.h>
#include <linux/swap.h>
#include <linux/vmalloc.h>

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

#include <drm/drm_cache.h>

#include "ttm_bo_internal.h"

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

int ttm_mem_io_reserve(struct ttm_device *bdev,
                       struct ttm_resource *mem)
{
        if (mem->bus.offset || mem->bus.addr)
                return 0;

        mem->bus.is_iomem = false;
        if (!bdev->funcs->io_mem_reserve)
                return 0;

        return bdev->funcs->io_mem_reserve(bdev, mem);
}

void ttm_mem_io_free(struct ttm_device *bdev,
                     struct ttm_resource *mem)
{
        if (!mem)
                return;

        if (!mem->bus.offset && !mem->bus.addr)
                return;

        if (bdev->funcs->io_mem_free)
                bdev->funcs->io_mem_free(bdev, mem);

        mem->bus.offset = 0;
        mem->bus.addr = NULL;
}

/**
 * ttm_move_memcpy - Helper to perform a memcpy ttm move operation.
 * @clear: Whether to clear rather than copy.
 * @num_pages: Number of pages of the operation.
 * @dst_iter: A struct ttm_kmap_iter representing the destination resource.
 * @src_iter: A struct ttm_kmap_iter representing the source resource.
 *
 * This function is intended to be able to move out async under a
 * dma-fence if desired.
 */
void ttm_move_memcpy(bool clear,
                     u32 num_pages,
                     struct ttm_kmap_iter *dst_iter,
                     struct ttm_kmap_iter *src_iter)
{
        const struct ttm_kmap_iter_ops *dst_ops = dst_iter->ops;
        const struct ttm_kmap_iter_ops *src_ops = src_iter->ops;
        struct iosys_map src_map, dst_map;
        pgoff_t i;

        /* Single TTM move. NOP */
        if (dst_ops->maps_tt && src_ops->maps_tt)
                return;

        /* Don't move nonexistent data. Clear destination instead. */
        if (clear) {
                for (i = 0; i < num_pages; ++i) {
                        dst_ops->map_local(dst_iter, &dst_map, i);
                        if (dst_map.is_iomem)
                                memset_io(dst_map.vaddr_iomem, 0, PAGE_SIZE);
                        else
                                memset(dst_map.vaddr, 0, PAGE_SIZE);
                        if (dst_ops->unmap_local)
                                dst_ops->unmap_local(dst_iter, &dst_map);
                }
                return;
        }

        for (i = 0; i < num_pages; ++i) {
                dst_ops->map_local(dst_iter, &dst_map, i);
                src_ops->map_local(src_iter, &src_map, i);

                drm_memcpy_from_wc(&dst_map, &src_map, PAGE_SIZE);

                if (src_ops->unmap_local)
                        src_ops->unmap_local(src_iter, &src_map);
                if (dst_ops->unmap_local)
                        dst_ops->unmap_local(dst_iter, &dst_map);
        }
}
EXPORT_SYMBOL(ttm_move_memcpy);

/**
 * ttm_bo_move_memcpy
 *
 * @bo: A pointer to a struct ttm_buffer_object.
 * @ctx: operation context
 * @dst_mem: struct ttm_resource indicating where to move.
 *
 * Fallback move function for a mappable buffer object in mappable memory.
 * The function will, if successful,
 * free any old aperture space, and set (@new_mem)->mm_node to NULL,
 * and update the (@bo)->mem placement flags. If unsuccessful, the old
 * data remains untouched, and it's up to the caller to free the
 * memory space indicated by @new_mem.
 * Returns:
 * !0: Failure.
 */
int ttm_bo_move_memcpy(struct ttm_buffer_object *bo,
                       struct ttm_operation_ctx *ctx,
                       struct ttm_resource *dst_mem)
{
        struct ttm_device *bdev = bo->bdev;
        struct ttm_resource_manager *dst_man =
                ttm_manager_type(bo->bdev, dst_mem->mem_type);
        struct ttm_tt *ttm = bo->ttm;
        struct ttm_resource *src_mem = bo->resource;
        struct ttm_resource_manager *src_man;
        union {
                struct ttm_kmap_iter_tt tt;
                struct ttm_kmap_iter_linear_io io;
        } _dst_iter, _src_iter;
        struct ttm_kmap_iter *dst_iter, *src_iter;
        bool clear;
        int ret = 0;

        if (WARN_ON(!src_mem))
                return -EINVAL;

        src_man = ttm_manager_type(bdev, src_mem->mem_type);
        if (ttm && ((ttm->page_flags & TTM_TT_FLAG_SWAPPED) ||
                    dst_man->use_tt)) {
                ret = ttm_bo_populate(bo, ctx);
                if (ret)
                        return ret;
        }

        dst_iter = ttm_kmap_iter_linear_io_init(&_dst_iter.io, bdev, dst_mem);
        if (PTR_ERR(dst_iter) == -EINVAL && dst_man->use_tt)
                dst_iter = ttm_kmap_iter_tt_init(&_dst_iter.tt, ttm);
        if (IS_ERR(dst_iter))
                return PTR_ERR(dst_iter);

        src_iter = ttm_kmap_iter_linear_io_init(&_src_iter.io, bdev, src_mem);
        if (PTR_ERR(src_iter) == -EINVAL && src_man->use_tt)
                src_iter = ttm_kmap_iter_tt_init(&_src_iter.tt, ttm);
        if (IS_ERR(src_iter)) {
                ret = PTR_ERR(src_iter);
                goto out_src_iter;
        }

        clear = src_iter->ops->maps_tt && (!ttm || !ttm_tt_is_populated(ttm));
        if (!(clear && ttm && !(ttm->page_flags & TTM_TT_FLAG_ZERO_ALLOC)))
                ttm_move_memcpy(clear, PFN_UP(dst_mem->size), dst_iter, src_iter);

        if (!src_iter->ops->maps_tt)
                ttm_kmap_iter_linear_io_fini(&_src_iter.io, bdev, src_mem);
        ttm_bo_move_sync_cleanup(bo, dst_mem);

out_src_iter:
        if (!dst_iter->ops->maps_tt)
                ttm_kmap_iter_linear_io_fini(&_dst_iter.io, bdev, dst_mem);

        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);
        dma_resv_fini(&fbo->base.base._resv);
        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_obj(*fbo);
        if (!fbo)
                return -ENOMEM;

        fbo->base = *bo;

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

        atomic_inc(&ttm_glob.bo_count);
        drm_vma_node_reset(&fbo->base.base.vma_node);

        kref_init(&fbo->base.kref);
        fbo->base.destroy = &ttm_transfered_destroy;
        fbo->base.pin_count = 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);

        ret = dma_resv_reserve_fences(&fbo->base.base._resv, TTM_NUM_MOVE_FENCES);
        if (ret) {
                dma_resv_unlock(&fbo->base.base._resv);
                kfree(fbo);
                return ret;
        }

        if (fbo->base.resource) {
                ttm_resource_set_bo(fbo->base.resource, &fbo->base);
                bo->resource = NULL;
                ttm_bo_set_bulk_move(&fbo->base, NULL);
        } else {
                fbo->base.bulk_move = NULL;
        }

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

        ttm_bo_move_to_lru_tail_unlocked(&fbo->base);

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

/**
 * ttm_io_prot
 *
 * @bo: ttm buffer object
 * @res: ttm resource object
 * @tmp: Page protection flag for a normal, cached mapping.
 *
 * Utility function that returns the pgprot_t that should be used for
 * setting up a PTE with the caching model indicated by @c_state.
 */
pgprot_t ttm_io_prot(struct ttm_buffer_object *bo, struct ttm_resource *res,
                     pgprot_t tmp)
{
        struct ttm_resource_manager *man;
        enum ttm_caching caching;

        man = ttm_manager_type(bo->bdev, res->mem_type);
        if (man->use_tt) {
                caching = bo->ttm->caching;
                if (bo->ttm->page_flags & TTM_TT_FLAG_DECRYPTED)
                        tmp = pgprot_decrypted(tmp);
        } else  {
                caching = res->bus.caching;
        }

        return ttm_prot_from_caching(caching, 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_resource *mem = bo->resource;

        if (mem->bus.addr) {
                map->bo_kmap_type = ttm_bo_map_premapped;
                map->virtual = ((u8 *)mem->bus.addr) + offset;
        } else {
                resource_size_t res = mem->bus.offset + offset;

                map->bo_kmap_type = ttm_bo_map_iomap;
                if (mem->bus.caching == ttm_write_combined)
                        map->virtual = ioremap_wc(res, size);
#ifdef CONFIG_X86
                else if (mem->bus.caching == ttm_cached)
                        map->virtual = ioremap_cache(res, size);
#endif
                else
                        map->virtual = ioremap(res, 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_resource *mem = bo->resource;
        struct ttm_operation_ctx ctx = { };
        struct ttm_tt *ttm = bo->ttm;
        struct ttm_resource_manager *man =
                        ttm_manager_type(bo->bdev, mem->mem_type);
        pgprot_t prot;
        int ret;

        BUG_ON(!ttm);

        ret = ttm_bo_populate(bo, &ctx);
        if (ret)
                return ret;

        if (num_pages == 1 && ttm->caching == ttm_cached &&
            !(man->use_tt && (ttm->page_flags & TTM_TT_FLAG_DECRYPTED))) {
                /*
                 * 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(bo, mem, 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;
}

/**
 * ttm_bo_kmap_try_from_panic
 *
 * @bo: The buffer object
 * @page: The page to map
 *
 * Sets up a kernel virtual mapping using kmap_local_page_try_from_panic().
 * This should only be called from the panic handler, if you make sure the bo
 * is the one being displayed, so is properly allocated, and protected.
 *
 * Returns the vaddr, that you can use to write to the bo, and that you should
 * pass to kunmap_local() when you're done with this page, or NULL if the bo
 * is in iomem.
 */
void *ttm_bo_kmap_try_from_panic(struct ttm_buffer_object *bo, unsigned long page)
{
        if (page + 1 > PFN_UP(bo->resource->size))
                return NULL;

        if (!bo->resource->bus.is_iomem && bo->ttm->pages && bo->ttm->pages[page])
                return kmap_local_page_try_from_panic(bo->ttm->pages[page]);

        return NULL;
}
EXPORT_SYMBOL(ttm_bo_kmap_try_from_panic);

/**
 * ttm_bo_kmap
 *
 * @bo: The buffer object.
 * @start_page: The first page to map.
 * @num_pages: Number of pages to map.
 * @map: pointer to a struct ttm_bo_kmap_obj representing the map.
 *
 * Sets up a kernel virtual mapping, using ioremap, vmap or kmap to the
 * data in the buffer object. The ttm_kmap_obj_virtual function can then be
 * used to obtain a virtual address to the data.
 *
 * Returns
 * -ENOMEM: Out of memory.
 * -EINVAL: Invalid range.
 */
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_resource *res = bo->resource;
        unsigned long offset, size;
        int ret;

        map->virtual = NULL;
        map->bo = bo;
        if (num_pages > PFN_UP(res->size))
                return -EINVAL;
        if ((start_page + num_pages) > PFN_UP(res->size))
                return -EINVAL;

        ret = ttm_mem_io_reserve(bo->bdev, res);
        if (ret)
                return ret;
        if (!res->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);

/**
 * ttm_bo_kunmap
 *
 * @map: Object describing the map to unmap.
 *
 * Unmaps a kernel map set up by ttm_bo_kmap.
 */
void ttm_bo_kunmap(struct ttm_bo_kmap_obj *map)
{
        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();
        }
        ttm_mem_io_free(map->bo->bdev, map->bo->resource);
        map->virtual = NULL;
        map->page = NULL;
}
EXPORT_SYMBOL(ttm_bo_kunmap);

/**
 * ttm_bo_vmap
 *
 * @bo: The buffer object.
 * @map: pointer to a struct iosys_map representing the map.
 *
 * Sets up a kernel virtual mapping, using ioremap or vmap to the
 * data in the buffer object. The parameter @map returns the virtual
 * address as struct iosys_map. Unmap the buffer with ttm_bo_vunmap().
 *
 * Returns
 * -ENOMEM: Out of memory.
 * -EINVAL: Invalid range.
 */
int ttm_bo_vmap(struct ttm_buffer_object *bo, struct iosys_map *map)
{
        struct ttm_resource *mem = bo->resource;
        int ret;

        dma_resv_assert_held(bo->base.resv);

        ret = ttm_mem_io_reserve(bo->bdev, mem);
        if (ret)
                return ret;

        if (mem->bus.is_iomem) {
                void __iomem *vaddr_iomem;

                if (mem->bus.addr)
                        vaddr_iomem = (void __iomem *)mem->bus.addr;
                else if (mem->bus.caching == ttm_write_combined)
                        vaddr_iomem = ioremap_wc(mem->bus.offset,
                                                 bo->base.size);
#ifdef CONFIG_X86
                else if (mem->bus.caching == ttm_cached)
                        vaddr_iomem = ioremap_cache(mem->bus.offset,
                                                  bo->base.size);
#endif
                else
                        vaddr_iomem = ioremap(mem->bus.offset, bo->base.size);

                if (!vaddr_iomem)
                        return -ENOMEM;

                iosys_map_set_vaddr_iomem(map, vaddr_iomem);

        } else {
                struct ttm_operation_ctx ctx = { };
                struct ttm_tt *ttm = bo->ttm;
                pgprot_t prot;
                void *vaddr;

                ret = ttm_bo_populate(bo, &ctx);
                if (ret)
                        return ret;

                /*
                 * We need to use vmap to get the desired page protection
                 * or to make the buffer object look contiguous.
                 */
                prot = ttm_io_prot(bo, mem, PAGE_KERNEL);
                vaddr = vmap(ttm->pages, ttm->num_pages, 0, prot);
                if (!vaddr)
                        return -ENOMEM;

                iosys_map_set_vaddr(map, vaddr);
        }

        return 0;
}
EXPORT_SYMBOL(ttm_bo_vmap);

/**
 * ttm_bo_vunmap
 *
 * @bo: The buffer object.
 * @map: Object describing the map to unmap.
 *
 * Unmaps a kernel map set up by ttm_bo_vmap().
 */
void ttm_bo_vunmap(struct ttm_buffer_object *bo, struct iosys_map *map)
{
        struct ttm_resource *mem = bo->resource;

        dma_resv_assert_held(bo->base.resv);

        if (iosys_map_is_null(map))
                return;

        if (!map->is_iomem)
                vunmap(map->vaddr);
        else if (!mem->bus.addr)
                iounmap(map->vaddr_iomem);
        iosys_map_clear(map);

        ttm_mem_io_free(bo->bdev, mem);
}
EXPORT_SYMBOL(ttm_bo_vunmap);

static int ttm_bo_wait_free_node(struct ttm_buffer_object *bo,
                                 bool dst_use_tt)
{
        long ret;

        ret = dma_resv_wait_timeout(bo->base.resv, DMA_RESV_USAGE_BOOKKEEP,
                                    false, 15 * HZ);
        if (ret == 0)
                return -EBUSY;
        if (ret < 0)
                return ret;

        if (!dst_use_tt)
                ttm_bo_tt_destroy(bo);
        ttm_resource_free(bo, &bo->resource);
        return 0;
}

static int ttm_bo_move_to_ghost(struct ttm_buffer_object *bo,
                                struct dma_fence *fence,
                                bool dst_use_tt)
{
        struct ttm_buffer_object *ghost_obj;
        int ret;

        /**
         * 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.
         */

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

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

        /**
         * 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 (dst_use_tt)
                ghost_obj->ttm = NULL;
        else
                bo->ttm = NULL;

        dma_resv_unlock(&ghost_obj->base._resv);
        ttm_bo_put(ghost_obj);
        return 0;
}

static void ttm_bo_move_pipeline_evict(struct ttm_buffer_object *bo,
                                       struct dma_fence *fence)
{
        struct ttm_resource_manager *from;
        struct dma_fence *tmp;
        int i;

        from = ttm_manager_type(bo->bdev, bo->resource->mem_type);

        /**
         * BO doesn't have a TTM we need to bind/unbind. Just remember
         * this eviction and free up the allocation.
         * The fence will be saved in the first free slot or in the slot
         * already used to store a fence from the same context. Since
         * drivers can't use more than TTM_NUM_MOVE_FENCES contexts for
         * evictions we should always find a slot to use.
         */
        spin_lock(&from->eviction_lock);
        for (i = 0; i < TTM_NUM_MOVE_FENCES; i++) {
                tmp = from->eviction_fences[i];
                if (!tmp)
                        break;
                if (fence->context != tmp->context)
                        continue;
                if (dma_fence_is_later(fence, tmp)) {
                        dma_fence_put(tmp);
                        break;
                }
                goto unlock;
        }
        if (i < TTM_NUM_MOVE_FENCES) {
                from->eviction_fences[i] = dma_fence_get(fence);
        } else {
                WARN(1, "not enough fence slots for all fence contexts");
                spin_unlock(&from->eviction_lock);
                dma_fence_wait(fence, false);
                goto end;
        }

unlock:
        spin_unlock(&from->eviction_lock);
end:
        ttm_resource_free(bo, &bo->resource);
}

/**
 * ttm_bo_move_accel_cleanup - cleanup helper for hw copies
 *
 * @bo: A pointer to a struct ttm_buffer_object.
 * @fence: A fence object that signals when moving is complete.
 * @evict: This is an evict move. Don't return until the buffer is idle.
 * @pipeline: evictions are to be pipelined.
 * @new_mem: struct ttm_resource indicating where to move.
 *
 * Accelerated move function to be called when an accelerated move
 * has been scheduled. The function will create a new temporary buffer object
 * representing the old placement, and put the sync object on both buffer
 * objects. After that the newly created buffer object is unref'd to be
 * destroyed when the move is complete. This will help pipeline
 * buffer moves.
 */
int ttm_bo_move_accel_cleanup(struct ttm_buffer_object *bo,
                              struct dma_fence *fence,
                              bool evict,
                              bool pipeline,
                              struct ttm_resource *new_mem)
{
        struct ttm_device *bdev = bo->bdev;
        struct ttm_resource_manager *from = ttm_manager_type(bdev, bo->resource->mem_type);
        struct ttm_resource_manager *man = ttm_manager_type(bdev, new_mem->mem_type);
        int ret = 0;

        dma_resv_add_fence(bo->base.resv, fence, DMA_RESV_USAGE_KERNEL);
        if (!evict)
                ret = ttm_bo_move_to_ghost(bo, fence, man->use_tt);
        else if (!from->use_tt && pipeline)
                ttm_bo_move_pipeline_evict(bo, fence);
        else
                ret = ttm_bo_wait_free_node(bo, man->use_tt);

        if (ret)
                return ret;

        ttm_bo_assign_mem(bo, new_mem);

        return 0;
}
EXPORT_SYMBOL(ttm_bo_move_accel_cleanup);

/**
 * ttm_bo_move_sync_cleanup - cleanup by waiting for the move to finish
 *
 * @bo: A pointer to a struct ttm_buffer_object.
 * @new_mem: struct ttm_resource indicating where to move.
 *
 * Special case of ttm_bo_move_accel_cleanup where the bo is guaranteed
 * by the caller to be idle. Typically used after memcpy buffer moves.
 */
void ttm_bo_move_sync_cleanup(struct ttm_buffer_object *bo,
                              struct ttm_resource *new_mem)
{
        struct ttm_resource_manager *man =
                ttm_manager_type(bo->bdev, new_mem->mem_type);
        int ret;

        ret = ttm_bo_wait_free_node(bo, man->use_tt);
        if (WARN_ON(ret))
                return;

        ttm_bo_assign_mem(bo, new_mem);
}
EXPORT_SYMBOL(ttm_bo_move_sync_cleanup);

/**
 * ttm_bo_pipeline_gutting - purge the contents of a bo
 * @bo: The buffer object
 *
 * Purge the contents of a bo, async if the bo is not idle.
 * After a successful call, the bo is left unpopulated in
 * system placement. The function may wait uninterruptible
 * for idle on OOM.
 *
 * Return: 0 if successful, negative error code on failure.
 */
int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo)
{
        struct ttm_buffer_object *ghost;
        struct ttm_tt *ttm;
        int ret;

        /* If already idle, no need for ghost object dance. */
        if (dma_resv_test_signaled(bo->base.resv, DMA_RESV_USAGE_BOOKKEEP)) {
                if (!bo->ttm) {
                        /* See comment below about clearing. */
                        ret = ttm_tt_create(bo, true);
                        if (ret)
                                return ret;
                } else {
                        ttm_tt_unpopulate(bo->bdev, bo->ttm);
                        if (bo->type == ttm_bo_type_device)
                                ttm_tt_mark_for_clear(bo->ttm);
                }
                ttm_resource_free(bo, &bo->resource);
                return 0;
        }

        /*
         * We need an unpopulated ttm_tt after giving our current one,
         * if any, to the ghost object. And we can't afford to fail
         * creating one *after* the operation. If the bo subsequently gets
         * resurrected, make sure it's cleared (if ttm_bo_type_device)
         * to avoid leaking sensitive information to user-space.
         */

        ttm = bo->ttm;
        bo->ttm = NULL;
        ret = ttm_tt_create(bo, true);
        swap(bo->ttm, ttm);
        if (ret)
                return ret;

        ret = ttm_buffer_object_transfer(bo, &ghost);
        if (ret)
                goto error_destroy_tt;

        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) {
                dma_resv_wait_timeout(bo->base.resv, DMA_RESV_USAGE_BOOKKEEP,
                                      false, MAX_SCHEDULE_TIMEOUT);
        }

        dma_resv_unlock(&ghost->base._resv);
        ttm_bo_put(ghost);
        bo->ttm = ttm;
        return 0;

error_destroy_tt:
        ttm_tt_destroy(bo->bdev, ttm);
        return ret;
}

static bool ttm_lru_walk_trylock(struct ttm_bo_lru_cursor *curs,
                                 struct ttm_buffer_object *bo)
{
        struct ttm_operation_ctx *ctx = curs->arg->ctx;

        curs->needs_unlock = false;

        if (dma_resv_trylock(bo->base.resv)) {
                curs->needs_unlock = true;
                return true;
        }

        if (bo->base.resv == ctx->resv && ctx->allow_res_evict) {
                dma_resv_assert_held(bo->base.resv);
                return true;
        }

        return false;
}

static int ttm_lru_walk_ticketlock(struct ttm_bo_lru_cursor *curs,
                                   struct ttm_buffer_object *bo)
{
        struct ttm_lru_walk_arg *arg = curs->arg;
        int ret;

        if (arg->ctx->interruptible)
                ret = dma_resv_lock_interruptible(bo->base.resv, arg->ticket);
        else
                ret = dma_resv_lock(bo->base.resv, arg->ticket);

        if (!ret) {
                curs->needs_unlock = true;
                /*
                 * Only a single ticketlock per loop. Ticketlocks are prone
                 * to return -EDEADLK causing the eviction to fail, so
                 * after waiting for the ticketlock, revert back to
                 * trylocking for this walk.
                 */
                arg->ticket = NULL;
        } else if (ret == -EDEADLK) {
                /* Caller needs to exit the ww transaction. */
                ret = -ENOSPC;
        }

        return ret;
}

/**
 * ttm_lru_walk_for_evict() - Perform a LRU list walk, with actions taken on
 * valid items.
 * @walk: describe the walks and actions taken
 * @bdev: The TTM device.
 * @man: The struct ttm_resource manager whose LRU lists we're walking.
 * @target: The end condition for the walk.
 *
 * The LRU lists of @man are walk, and for each struct ttm_resource encountered,
 * the corresponding ttm_buffer_object is locked and taken a reference on, and
 * the LRU lock is dropped. the LRU lock may be dropped before locking and, in
 * that case, it's verified that the item actually remains on the LRU list after
 * the lock, and that the buffer object didn't switch resource in between.
 *
 * With a locked object, the actions indicated by @walk->process_bo are
 * performed, and after that, the bo is unlocked, the refcount dropped and the
 * next struct ttm_resource is processed. Here, the walker relies on
 * TTM's restartable LRU list implementation.
 *
 * Typically @walk->process_bo() would return the number of pages evicted,
 * swapped or shrunken, so that when the total exceeds @target, or when the
 * LRU list has been walked in full, iteration is terminated. It's also terminated
 * on error. Note that the definition of @target is done by the caller, it
 * could have a different meaning than the number of pages.
 *
 * Note that the way dma_resv individualization is done, locking needs to be done
 * either with the LRU lock held (trylocking only) or with a reference on the
 * object.
 *
 * Return: The progress made towards target or negative error code on error.
 */
s64 ttm_lru_walk_for_evict(struct ttm_lru_walk *walk, struct ttm_device *bdev,
                           struct ttm_resource_manager *man, s64 target)
{
        struct ttm_bo_lru_cursor cursor;
        struct ttm_buffer_object *bo;
        s64 progress = 0;
        s64 lret;

        ttm_bo_lru_for_each_reserved_guarded(&cursor, man, &walk->arg, bo) {
                lret = walk->ops->process_bo(walk, bo);
                if (lret == -EBUSY || lret == -EALREADY)
                        lret = 0;
                progress = (lret < 0) ? lret : progress + lret;
                if (progress < 0 || progress >= target)
                        break;
        }
        if (IS_ERR(bo))
                return PTR_ERR(bo);

        return progress;
}
EXPORT_SYMBOL(ttm_lru_walk_for_evict);

static void ttm_bo_lru_cursor_cleanup_bo(struct ttm_bo_lru_cursor *curs)
{
        struct ttm_buffer_object *bo = curs->bo;

        if (bo) {
                if (curs->needs_unlock)
                        dma_resv_unlock(bo->base.resv);
                ttm_bo_put(bo);
                curs->bo = NULL;
        }
}

/**
 * ttm_bo_lru_cursor_fini() - Stop using a struct ttm_bo_lru_cursor
 * and clean up any iteration it was used for.
 * @curs: The cursor.
 */
void ttm_bo_lru_cursor_fini(struct ttm_bo_lru_cursor *curs)
{
        spinlock_t *lru_lock = &curs->res_curs.man->bdev->lru_lock;

        ttm_bo_lru_cursor_cleanup_bo(curs);
        spin_lock(lru_lock);
        ttm_resource_cursor_fini(&curs->res_curs);
        spin_unlock(lru_lock);
}
EXPORT_SYMBOL(ttm_bo_lru_cursor_fini);

/**
 * ttm_bo_lru_cursor_init() - Initialize a struct ttm_bo_lru_cursor
 * @curs: The ttm_bo_lru_cursor to initialize.
 * @man: The ttm resource_manager whose LRU lists to iterate over.
 * @arg: The ttm_lru_walk_arg to govern the walk.
 *
 * Initialize a struct ttm_bo_lru_cursor.
 *
 * Return: Pointer to @curs. The function does not fail.
 */
struct ttm_bo_lru_cursor *
ttm_bo_lru_cursor_init(struct ttm_bo_lru_cursor *curs,
                       struct ttm_resource_manager *man,
                       struct ttm_lru_walk_arg *arg)
{
        memset(curs, 0, sizeof(*curs));
        ttm_resource_cursor_init(&curs->res_curs, man);
        curs->arg = arg;

        return curs;
}
EXPORT_SYMBOL(ttm_bo_lru_cursor_init);

static struct ttm_buffer_object *
__ttm_bo_lru_cursor_next(struct ttm_bo_lru_cursor *curs)
{
        spinlock_t *lru_lock = &curs->res_curs.man->bdev->lru_lock;
        struct ttm_resource *res = NULL;
        struct ttm_buffer_object *bo;
        struct ttm_lru_walk_arg *arg = curs->arg;
        bool first = !curs->bo;

        ttm_bo_lru_cursor_cleanup_bo(curs);

        spin_lock(lru_lock);
        for (;;) {
                int mem_type, ret = 0;
                bool bo_locked = false;

                if (first) {
                        res = ttm_resource_manager_first(&curs->res_curs);
                        first = false;
                } else {
                        res = ttm_resource_manager_next(&curs->res_curs);
                }
                if (!res)
                        break;

                bo = res->bo;
                if (ttm_lru_walk_trylock(curs, bo))
                        bo_locked = true;
                else if (!arg->ticket || arg->ctx->no_wait_gpu || arg->trylock_only)
                        continue;

                if (!ttm_bo_get_unless_zero(bo)) {
                        if (curs->needs_unlock)
                                dma_resv_unlock(bo->base.resv);
                        continue;
                }

                mem_type = res->mem_type;
                spin_unlock(lru_lock);
                if (!bo_locked)
                        ret = ttm_lru_walk_ticketlock(curs, bo);

                /*
                 * Note that in between the release of the lru lock and the
                 * ticketlock, the bo may have switched resource,
                 * and also memory type, since the resource may have been
                 * freed and allocated again with a different memory type.
                 * In that case, just skip it.
                 */
                curs->bo = bo;
                if (!ret && bo->resource && bo->resource->mem_type == mem_type)
                        return bo;

                ttm_bo_lru_cursor_cleanup_bo(curs);
                if (ret && ret != -EALREADY)
                        return ERR_PTR(ret);

                spin_lock(lru_lock);
        }

        spin_unlock(lru_lock);
        return res ? bo : NULL;
}

/**
 * ttm_bo_lru_cursor_next() - Continue iterating a manager's LRU lists
 * to find and lock buffer object.
 * @curs: The cursor initialized using ttm_bo_lru_cursor_init() and
 * ttm_bo_lru_cursor_first().
 *
 * Return: A pointer to a locked and reference-counted buffer object,
 * or NULL if none could be found and looping should be terminated.
 */
struct ttm_buffer_object *ttm_bo_lru_cursor_next(struct ttm_bo_lru_cursor *curs)
{
        return __ttm_bo_lru_cursor_next(curs);
}
EXPORT_SYMBOL(ttm_bo_lru_cursor_next);

/**
 * ttm_bo_lru_cursor_first() - Start iterating a manager's LRU lists
 * to find and lock buffer object.
 * @curs: The cursor initialized using ttm_bo_lru_cursor_init().
 *
 * Return: A pointer to a locked and reference-counted buffer object,
 * or NULL if none could be found and looping should be terminated.
 */
struct ttm_buffer_object *ttm_bo_lru_cursor_first(struct ttm_bo_lru_cursor *curs)
{
        ttm_bo_lru_cursor_cleanup_bo(curs);
        return __ttm_bo_lru_cursor_next(curs);
}
EXPORT_SYMBOL(ttm_bo_lru_cursor_first);

/**
 * ttm_bo_shrink() - Helper to shrink a ttm buffer object.
 * @ctx: The struct ttm_operation_ctx used for the shrinking operation.
 * @bo: The buffer object.
 * @flags: Flags governing the shrinking behaviour.
 *
 * The function uses the ttm_tt_back_up functionality to back up or
 * purge a struct ttm_tt. If the bo is not in system, it's first
 * moved there.
 *
 * Return: The number of pages shrunken or purged, or
 * negative error code on failure.
 */
long ttm_bo_shrink(struct ttm_operation_ctx *ctx, struct ttm_buffer_object *bo,
                   const struct ttm_bo_shrink_flags flags)
{
        static const struct ttm_place sys_placement_flags = {
                .fpfn = 0,
                .lpfn = 0,
                .mem_type = TTM_PL_SYSTEM,
                .flags = 0,
        };
        static struct ttm_placement sys_placement = {
                .num_placement = 1,
                .placement = &sys_placement_flags,
        };
        struct ttm_device *bdev = bo->bdev;
        long lret;

        dma_resv_assert_held(bo->base.resv);

        if (flags.allow_move && bo->resource->mem_type != TTM_PL_SYSTEM) {
                int ret = ttm_bo_validate(bo, &sys_placement, ctx);

                /* Consider -ENOMEM and -ENOSPC non-fatal. */
                if (ret) {
                        if (ret == -ENOMEM || ret == -ENOSPC)
                                ret = -EBUSY;
                        return ret;
                }
        }

        ttm_bo_unmap_virtual(bo);
        lret = ttm_bo_wait_ctx(bo, ctx);
        if (lret < 0)
                return lret;

        lret = ttm_tt_backup(bdev, bo->ttm, (struct ttm_backup_flags)
                             {.purge = flags.purge,
                              .writeback = flags.writeback});

        if (lret > 0) {
                spin_lock(&bdev->lru_lock);
                ttm_resource_del_bulk_move_unevictable(bo->resource, bo);
                ttm_resource_move_to_lru_tail(bo->resource);
                spin_unlock(&bdev->lru_lock);
        }

        if (lret < 0 && lret != -EINTR)
                return -EBUSY;

        return lret;
}
EXPORT_SYMBOL(ttm_bo_shrink);

/**
 * ttm_bo_shrink_suitable() - Whether a bo is suitable for shinking
 * @ctx: The struct ttm_operation_ctx governing the shrinking.
 * @bo: The candidate for shrinking.
 *
 * Check whether the object, given the information available to TTM,
 * is suitable for shinking, This function can and should be used
 * before attempting to shrink an object.
 *
 * Return: true if suitable. false if not.
 */
bool ttm_bo_shrink_suitable(struct ttm_buffer_object *bo, struct ttm_operation_ctx *ctx)
{
        return bo->ttm && ttm_tt_is_populated(bo->ttm) && !bo->pin_count &&
                (!ctx->no_wait_gpu ||
                 dma_resv_test_signaled(bo->base.resv, DMA_RESV_USAGE_BOOKKEEP));
}
EXPORT_SYMBOL(ttm_bo_shrink_suitable);

/**
 * ttm_bo_shrink_avoid_wait() - Whether to avoid waiting for GPU
 * during shrinking
 *
 * In some situations, like direct reclaim, waiting (in particular gpu waiting)
 * should be avoided since it may stall a system that could otherwise make progress
 * shrinking something else less time consuming.
 *
 * Return: true if gpu waiting should be avoided, false if not.
 */
bool ttm_bo_shrink_avoid_wait(void)
{
        return !current_is_kswapd();
}
EXPORT_SYMBOL(ttm_bo_shrink_avoid_wait);