[linux-2.6-microblaze.git] / drivers / gpu / drm / ttm / ttm_bo.c

/* 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/ttm/ttm_bo.h>
#include <drm/ttm/ttm_placement.h>
#include <drm/ttm/ttm_tt.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/dma-resv.h>

#include "ttm_module.h"

static void ttm_bo_mem_space_debug(struct ttm_buffer_object *bo,
                                        struct ttm_placement *placement)
{
        struct drm_printer p = drm_debug_printer(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.
 *
 * 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_tt_populate(bo->bdev, bo->ttm, 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);
}

/**
 * ttm_bo_cleanup_refs
 * If bo idle, remove from lru lists, and unref.
 * If not idle, block if possible.
 *
 * Must be called with lru_lock and reservation held, this function
 * will drop the lru lock and optionally the reservation lock before returning.
 *
 * @bo:                    The buffer object to clean-up
 * @interruptible:         Any sleeps should occur interruptibly.
 * @no_wait_gpu:           Never wait for gpu. Return -EBUSY instead.
 * @unlock_resv:           Unlock the reservation lock as well.
 */

static int ttm_bo_cleanup_refs(struct ttm_buffer_object *bo,
                               bool interruptible, bool no_wait_gpu,
                               bool unlock_resv)
{
        struct dma_resv *resv = &bo->base._resv;
        int ret;

        if (dma_resv_test_signaled(resv, DMA_RESV_USAGE_BOOKKEEP))
                ret = 0;
        else
                ret = -EBUSY;

        if (ret && !no_wait_gpu) {
                long lret;

                if (unlock_resv)
                        dma_resv_unlock(bo->base.resv);
                spin_unlock(&bo->bdev->lru_lock);

                lret = dma_resv_wait_timeout(resv, DMA_RESV_USAGE_BOOKKEEP,
                                             interruptible,
                                             30 * HZ);

                if (lret < 0)
                        return lret;
                else if (lret == 0)
                        return -EBUSY;

                spin_lock(&bo->bdev->lru_lock);
                if (unlock_resv && !dma_resv_trylock(bo->base.resv)) {
                        /*
                         * We raced, and lost, someone else holds the reservation now,
                         * and is probably busy in ttm_bo_cleanup_memtype_use.
                         *
                         * Even if it's not the case, because we finished waiting any
                         * delayed destruction would succeed, so just return success
                         * here.
                         */
                        spin_unlock(&bo->bdev->lru_lock);
                        return 0;
                }
                ret = 0;
        }

        if (ret) {
                if (unlock_resv)
                        dma_resv_unlock(bo->base.resv);
                spin_unlock(&bo->bdev->lru_lock);
                return ret;
        }

        spin_unlock(&bo->bdev->lru_lock);
        ttm_bo_cleanup_memtype_use(bo);

        if (unlock_resv)
                dma_resv_unlock(bo->base.resv);

        ttm_bo_put(bo);

        return 0;
}

/*
 * 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 (bo->bdev->funcs->release_notify)
                        bo->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) ||
                    !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(&bo->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(&bo->bdev->lru_lock);

                        INIT_WORK(&bo->delayed_delete, ttm_bo_delayed_delete);
                        queue_work(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);
}

/**
 * ttm_bo_put
 *
 * @bo: The buffer object.
 *
 * Unreference a buffer object.
 */
void ttm_bo_put(struct ttm_buffer_object *bo)
{
        kref_put(&bo->kref, ttm_bo_release);
}
EXPORT_SYMBOL(ttm_bo_put);

static int ttm_bo_bounce_temp_buffer(struct ttm_buffer_object *bo,
                                     struct ttm_resource **mem,
                                     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 = hop_placement.num_busy_placement = 1;
        hop_placement.placement = hop_placement.busy_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_device *bdev = bo->bdev;
        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;
        placement.num_busy_placement = 0;
        bdev->funcs->evict_flags(bo, &placement);

        if (!placement.num_placement && !placement.num_busy_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;
        }

bounce:
        ret = ttm_bo_handle_move_mem(bo, evict_mem, true, ctx, &hop);
        if (ret == -EMULTIHOP) {
                ret = ttm_bo_bounce_temp_buffer(bo, &evict_mem, ctx, &hop);
                if (ret) {
                        pr_err("Buffer eviction failed\n");
                        ttm_resource_free(bo, &evict_mem);
                        goto out;
                }
                /* try and move to final place now. */
                goto bounce;
        }
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;
        struct ttm_device *bdev = bo->bdev;

        dma_resv_assert_held(bo->base.resv);
        if (bo->resource->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(bdev, res, place, bo->base.size);
}
EXPORT_SYMBOL(ttm_bo_eviction_valuable);

/*
 * Check the target bo is allowable to be evicted or swapout, including cases:
 *
 * a. if share same reservation object with ctx->resv, have assumption
 * reservation objects should already be locked, so not lock again and
 * return true directly when either the opreation allow_reserved_eviction
 * or the target bo already is in delayed free list;
 *
 * b. Otherwise, trylock it.
 */
static bool ttm_bo_evict_swapout_allowable(struct ttm_buffer_object *bo,
                                           struct ttm_operation_ctx *ctx,
                                           const struct ttm_place *place,
                                           bool *locked, bool *busy)
{
        bool ret = false;

        if (bo->base.resv == ctx->resv) {
                dma_resv_assert_held(bo->base.resv);
                if (ctx->allow_res_evict)
                        ret = true;
                *locked = false;
                if (busy)
                        *busy = false;
        } else {
                ret = dma_resv_trylock(bo->base.resv);
                *locked = ret;
                if (busy)
                        *busy = !ret;
        }

        if (ret && place && (bo->resource->mem_type != place->mem_type ||
                !bo->bdev->funcs->eviction_valuable(bo, place))) {
                ret = false;
                if (*locked) {
                        dma_resv_unlock(bo->base.resv);
                        *locked = false;
                }
        }

        return ret;
}

/**
 * ttm_mem_evict_wait_busy - wait for a busy BO to become available
 *
 * @busy_bo: BO which couldn't be locked with trylock
 * @ctx: operation context
 * @ticket: acquire ticket
 *
 * Try to lock a busy buffer object to avoid failing eviction.
 */
static int ttm_mem_evict_wait_busy(struct ttm_buffer_object *busy_bo,
                                   struct ttm_operation_ctx *ctx,
                                   struct ww_acquire_ctx *ticket)
{
        int r;

        if (!busy_bo || !ticket)
                return -EBUSY;

        if (ctx->interruptible)
                r = dma_resv_lock_interruptible(busy_bo->base.resv,
                                                          ticket);
        else
                r = dma_resv_lock(busy_bo->base.resv, ticket);

        /*
         * TODO: It would be better to keep the BO locked until allocation is at
         * least tried one more time, but that would mean a much larger rework
         * of TTM.
         */
        if (!r)
                dma_resv_unlock(busy_bo->base.resv);

        return r == -EDEADLK ? -EBUSY : r;
}

int ttm_mem_evict_first(struct ttm_device *bdev,
                        struct ttm_resource_manager *man,
                        const struct ttm_place *place,
                        struct ttm_operation_ctx *ctx,
                        struct ww_acquire_ctx *ticket)
{
        struct ttm_buffer_object *bo = NULL, *busy_bo = NULL;
        struct ttm_resource_cursor cursor;
        struct ttm_resource *res;
        bool locked = false;
        int ret;

        spin_lock(&bdev->lru_lock);
        ttm_resource_manager_for_each_res(man, &cursor, res) {
                bool busy;

                if (!ttm_bo_evict_swapout_allowable(res->bo, ctx, place,
                                                    &locked, &busy)) {
                        if (busy && !busy_bo && ticket !=
                            dma_resv_locking_ctx(res->bo->base.resv))
                                busy_bo = res->bo;
                        continue;
                }

                if (ttm_bo_get_unless_zero(res->bo)) {
                        bo = res->bo;
                        break;
                }
                if (locked)
                        dma_resv_unlock(res->bo->base.resv);
        }

        if (!bo) {
                if (busy_bo && !ttm_bo_get_unless_zero(busy_bo))
                        busy_bo = NULL;
                spin_unlock(&bdev->lru_lock);
                ret = ttm_mem_evict_wait_busy(busy_bo, ctx, ticket);
                if (busy_bo)
                        ttm_bo_put(busy_bo);
                return ret;
        }

        if (bo->deleted) {
                ret = ttm_bo_cleanup_refs(bo, ctx->interruptible,
                                          ctx->no_wait_gpu, locked);
                ttm_bo_put(bo);
                return ret;
        }

        spin_unlock(&bdev->lru_lock);

        ret = ttm_bo_evict(bo, ctx);
        if (locked)
                ttm_bo_unreserve(bo);
        else
                ttm_bo_move_to_lru_tail_unlocked(bo);

        ttm_bo_put(bo);
        return ret;
}

/**
 * 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);
        ++bo->pin_count;
        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);
        --bo->pin_count;
        if (bo->resource)
                ttm_resource_add_bulk_move(bo->resource, bo);
        spin_unlock(&bo->bdev->lru_lock);
}
EXPORT_SYMBOL(ttm_bo_unpin);

/*
 * Add the last move fence to the BO as kernel dependency and reserve a new
 * fence slot.
 */
static int ttm_bo_add_move_fence(struct ttm_buffer_object *bo,
                                 struct ttm_resource_manager *man,
                                 struct ttm_resource *mem,
                                 bool no_wait_gpu)
{
        struct dma_fence *fence;
        int ret;

        spin_lock(&man->move_lock);
        fence = dma_fence_get(man->move);
        spin_unlock(&man->move_lock);

        if (!fence)
                return 0;

        if (no_wait_gpu) {
                ret = dma_fence_is_signaled(fence) ? 0 : -EBUSY;
                dma_fence_put(fence);
                return ret;
        }

        dma_resv_add_fence(bo->base.resv, fence, DMA_RESV_USAGE_KERNEL);

        ret = dma_resv_reserve_fences(bo->base.resv, 1);
        dma_fence_put(fence);
        return ret;
}

/*
 * Repeatedly evict memory from the LRU for @mem_type until we create enough
 * space, or we've evicted everything and there isn't enough space.
 */
static int ttm_bo_mem_force_space(struct ttm_buffer_object *bo,
                                  const struct ttm_place *place,
                                  struct ttm_resource **mem,
                                  struct ttm_operation_ctx *ctx)
{
        struct ttm_device *bdev = bo->bdev;
        struct ttm_resource_manager *man;
        struct ww_acquire_ctx *ticket;
        int ret;

        man = ttm_manager_type(bdev, place->mem_type);
        ticket = dma_resv_locking_ctx(bo->base.resv);
        do {
                ret = ttm_resource_alloc(bo, place, mem);
                if (likely(!ret))
                        break;
                if (unlikely(ret != -ENOSPC))
                        return ret;
                ret = ttm_mem_evict_first(bdev, man, place, ctx,
                                          ticket);
                if (unlikely(ret != 0))
                        return ret;
        } while (1);

        return ttm_bo_add_move_fence(bo, man, *mem, ctx->no_wait_gpu);
}

/**
 * ttm_bo_mem_space
 *
 * @bo: Pointer to a struct ttm_buffer_object. the data of which
 * we want to allocate space for.
 * @proposed_placement: Proposed new placement for the buffer object.
 * @mem: A struct ttm_resource.
 * @ctx: if and how to sleep, lock buffers and alloc memory
 *
 * Allocate memory space for the buffer object pointed to by @bo, using
 * the placement flags in @placement, potentially evicting other idle buffer objects.
 * This function may sleep while waiting for space to become available.
 * Returns:
 * -EBUSY: No space available (only if no_wait == 1).
 * -ENOMEM: Could not allocate memory for the buffer object, either due to
 * fragmentation or concurrent allocators.
 * -ERESTARTSYS: An interruptible sleep was interrupted by a signal.
 */
int ttm_bo_mem_space(struct ttm_buffer_object *bo,
                        struct ttm_placement *placement,
                        struct ttm_resource **mem,
                        struct ttm_operation_ctx *ctx)
{
        struct ttm_device *bdev = bo->bdev;
        bool type_found = false;
        int i, ret;

        ret = dma_resv_reserve_fences(bo->base.resv, 1);
        if (unlikely(ret))
                return ret;

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

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

                type_found = true;
                ret = ttm_resource_alloc(bo, place, mem);
                if (ret == -ENOSPC)
                        continue;
                if (unlikely(ret))
                        goto error;

                ret = ttm_bo_add_move_fence(bo, man, *mem, ctx->no_wait_gpu);
                if (unlikely(ret)) {
                        ttm_resource_free(bo, mem);
                        if (ret == -EBUSY)
                                continue;

                        goto error;
                }
                return 0;
        }

        for (i = 0; i < placement->num_busy_placement; ++i) {
                const struct ttm_place *place = &placement->busy_placement[i];
                struct ttm_resource_manager *man;

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

                type_found = true;
                ret = ttm_bo_mem_force_space(bo, place, mem, ctx);
                if (likely(!ret))
                        return 0;

                if (ret && ret != -EBUSY)
                        goto error;
        }

        ret = -ENOMEM;
        if (!type_found) {
                pr_err(TTM_PFX "No compatible memory type found\n");
                ret = -EINVAL;
        }

error:
        return ret;
}
EXPORT_SYMBOL(ttm_bo_mem_space);

static int ttm_bo_move_buffer(struct ttm_buffer_object *bo,
                              struct ttm_placement *placement,
                              struct ttm_operation_ctx *ctx)
{
        struct ttm_resource *mem;
        struct ttm_place hop;
        int ret;

        dma_resv_assert_held(bo->base.resv);

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

/**
 * 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)
{
        int ret;

        dma_resv_assert_held(bo->base.resv);

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

        /* Check whether we need to move buffer. */
        if (bo->resource && ttm_resource_compat(bo->resource, placement))
                return 0;

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

        ret = ttm_bo_move_buffer(bo, placement, ctx);
        if (ret)
                return ret;

        /*
         * 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, false };
        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);

int ttm_bo_swapout(struct ttm_buffer_object *bo, struct ttm_operation_ctx *ctx,
                   gfp_t gfp_flags)
{
        struct ttm_place place;
        bool locked;
        long 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.
         */
        memset(&place, 0, sizeof(place));
        place.mem_type = bo->resource->mem_type;
        if (!ttm_bo_evict_swapout_allowable(bo, ctx, &place, &locked, NULL))
                return -EBUSY;

        if (!bo->ttm || !ttm_tt_is_populated(bo->ttm) ||
            bo->ttm->page_flags & TTM_TT_FLAG_EXTERNAL ||
            bo->ttm->page_flags & TTM_TT_FLAG_SWAPPED ||
            !ttm_bo_get_unless_zero(bo)) {
                if (locked)
                        dma_resv_unlock(bo->base.resv);
                return -EBUSY;
        }

        if (bo->deleted) {
                ret = ttm_bo_cleanup_refs(bo, false, false, locked);
                ttm_bo_put(bo);
                return ret == -EBUSY ? -ENOSPC : ret;
        }

        /* TODO: Cleanup the locking */
        spin_unlock(&bo->bdev->lru_lock);

        /*
         * Move to system cached
         */
        if (bo->resource->mem_type != TTM_PL_SYSTEM) {
                struct ttm_operation_ctx ctx = { false, false };
                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);
                if (unlikely(ret))
                        goto out;

                ret = ttm_bo_handle_move_mem(bo, evict_mem, true, &ctx, &hop);
                if (unlikely(ret != 0)) {
                        WARN(ret == -EMULTIHOP, "Unexpected multihop in swaput - likely driver bug.\n");
                        goto out;
                }
        }

        /*
         * Make sure BO is idle.
         */
        ret = ttm_bo_wait_ctx(bo, ctx);
        if (unlikely(ret != 0))
                goto out;

        ttm_bo_unmap_virtual(bo);

        /*
         * Swap out. Buffer will be swapped in again as soon as
         * anyone tries to access a ttm page.
         */
        if (bo->bdev->funcs->swap_notify)
                bo->bdev->funcs->swap_notify(bo);

        if (ttm_tt_is_populated(bo->ttm))
                ret = ttm_tt_swapout(bo->bdev, bo->ttm, gfp_flags);
out:

        /*
         * Unreserve without putting on LRU to avoid swapping out an
         * already swapped buffer.
         */
        if (locked)
                dma_resv_unlock(bo->base.resv);
        ttm_bo_put(bo);
        return ret == -EBUSY ? -ENOSPC : ret;
}

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;
}