/*
 * Copyright 2018 Red Hat Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */
#include "nouveau_dmem.h"
#include "nouveau_drv.h"
#include "nouveau_chan.h"
#include "nouveau_dma.h"
#include "nouveau_mem.h"
#include "nouveau_bo.h"

#include <nvif/class.h>
#include <nvif/object.h>
#include <nvif/if500b.h>
#include <nvif/if900b.h>

#include <linux/sched/mm.h>
#include <linux/hmm.h>

/*
 * FIXME: this is ugly right now we are using TTM to allocate vram and we pin
 * it in vram while in use. We likely want to overhaul memory management for
 * nouveau to be more page like (not necessarily with system page size but a
 * bigger page size) at lowest level and have some shim layer on top that would
 * provide the same functionality as TTM.
 */
#define DMEM_CHUNK_SIZE (2UL << 20)
#define DMEM_CHUNK_NPAGES (DMEM_CHUNK_SIZE >> PAGE_SHIFT)

struct nouveau_migrate;

enum nouveau_aper {
        NOUVEAU_APER_VIRT,
        NOUVEAU_APER_VRAM,
        NOUVEAU_APER_HOST,
};

typedef int (*nouveau_migrate_copy_t)(struct nouveau_drm *drm, u64 npages,
                                      enum nouveau_aper, u64 dst_addr,
                                      enum nouveau_aper, u64 src_addr);

struct nouveau_dmem_chunk {
        struct list_head list;
        struct nouveau_bo *bo;
        struct nouveau_drm *drm;
        unsigned long pfn_first;
        unsigned long callocated;
        unsigned long bitmap[BITS_TO_LONGS(DMEM_CHUNK_NPAGES)];
        spinlock_t lock;
};

struct nouveau_dmem_migrate {
        nouveau_migrate_copy_t copy_func;
        struct nouveau_channel *chan;
};

struct nouveau_dmem {
        struct hmm_devmem *devmem;
        struct nouveau_dmem_migrate migrate;
        struct list_head chunk_free;
        struct list_head chunk_full;
        struct list_head chunk_empty;
        struct mutex mutex;
};

struct nouveau_dmem_fault {
        struct nouveau_drm *drm;
        struct nouveau_fence *fence;
        dma_addr_t *dma;
        unsigned long npages;
};

struct nouveau_migrate {
        struct vm_area_struct *vma;
        struct nouveau_drm *drm;
        struct nouveau_fence *fence;
        unsigned long npages;
        dma_addr_t *dma;
        unsigned long dma_nr;
};

static void
nouveau_dmem_free(struct hmm_devmem *devmem, struct page *page)
{
        struct nouveau_dmem_chunk *chunk;
        unsigned long idx;

        chunk = (void *)hmm_devmem_page_get_drvdata(page);
        idx = page_to_pfn(page) - chunk->pfn_first;

        /*
         * FIXME:
         *
         * This is really a bad example, we need to overhaul nouveau memory
         * management to be more page focus and allow lighter locking scheme
         * to be use in the process.
         */
        spin_lock(&chunk->lock);
        clear_bit(idx, chunk->bitmap);
        WARN_ON(!chunk->callocated);
        chunk->callocated--;
        /*
         * FIXME when chunk->callocated reach 0 we should add the chunk to
         * a reclaim list so that it can be freed in case of memory pressure.
         */
        spin_unlock(&chunk->lock);
}

static void
nouveau_dmem_fault_alloc_and_copy(struct vm_area_struct *vma,
                                  const unsigned long *src_pfns,
                                  unsigned long *dst_pfns,
                                  unsigned long start,
                                  unsigned long end,
                                  void *private)
{
        struct nouveau_dmem_fault *fault = private;
        struct nouveau_drm *drm = fault->drm;
        struct device *dev = drm->dev->dev;
        unsigned long addr, i, npages = 0;
        nouveau_migrate_copy_t copy;
        int ret;


        /* First allocate new memory */
        for (addr = start, i = 0; addr < end; addr += PAGE_SIZE, i++) {
                struct page *dpage, *spage;

                dst_pfns[i] = 0;
                spage = migrate_pfn_to_page(src_pfns[i]);
                if (!spage || !(src_pfns[i] & MIGRATE_PFN_MIGRATE))
                        continue;

                dpage = hmm_vma_alloc_locked_page(vma, addr);
                if (!dpage) {
                        dst_pfns[i] = MIGRATE_PFN_ERROR;
                        continue;
                }

                dst_pfns[i] = migrate_pfn(page_to_pfn(dpage)) |
                              MIGRATE_PFN_LOCKED;
                npages++;
        }

        /* Allocate storage for DMA addresses, so we can unmap later. */
        fault->dma = kmalloc(sizeof(*fault->dma) * npages, GFP_KERNEL);
        if (!fault->dma)
                goto error;

        /* Copy things over */
        copy = drm->dmem->migrate.copy_func;
        for (addr = start, i = 0; addr < end; addr += PAGE_SIZE, i++) {
                struct nouveau_dmem_chunk *chunk;
                struct page *spage, *dpage;
                u64 src_addr, dst_addr;

                dpage = migrate_pfn_to_page(dst_pfns[i]);
                if (!dpage || dst_pfns[i] == MIGRATE_PFN_ERROR)
                        continue;

                spage = migrate_pfn_to_page(src_pfns[i]);
                if (!spage || !(src_pfns[i] & MIGRATE_PFN_MIGRATE)) {
                        dst_pfns[i] = MIGRATE_PFN_ERROR;
                        __free_page(dpage);
                        continue;
                }

                fault->dma[fault->npages] =
                        dma_map_page_attrs(dev, dpage, 0, PAGE_SIZE,
                                           PCI_DMA_BIDIRECTIONAL,
                                           DMA_ATTR_SKIP_CPU_SYNC);
                if (dma_mapping_error(dev, fault->dma[fault->npages])) {
                        dst_pfns[i] = MIGRATE_PFN_ERROR;
                        __free_page(dpage);
                        continue;
                }

                dst_addr = fault->dma[fault->npages++];

                chunk = (void *)hmm_devmem_page_get_drvdata(spage);
                src_addr = page_to_pfn(spage) - chunk->pfn_first;
                src_addr = (src_addr << PAGE_SHIFT) + chunk->bo->bo.offset;

                ret = copy(drm, 1, NOUVEAU_APER_HOST, dst_addr,
                                   NOUVEAU_APER_VRAM, src_addr);
                if (ret) {
                        dst_pfns[i] = MIGRATE_PFN_ERROR;
                        __free_page(dpage);
                        continue;
                }
        }

        nouveau_fence_new(drm->dmem->migrate.chan, false, &fault->fence);

        return;

error:
        for (addr = start, i = 0; addr < end; addr += PAGE_SIZE, ++i) {
                struct page *page;

                if (!dst_pfns[i] || dst_pfns[i] == MIGRATE_PFN_ERROR)
                        continue;

                page = migrate_pfn_to_page(dst_pfns[i]);
                dst_pfns[i] = MIGRATE_PFN_ERROR;
                if (page == NULL)
                        continue;

                __free_page(page);
        }
}

void nouveau_dmem_fault_finalize_and_map(struct vm_area_struct *vma,
                                         const unsigned long *src_pfns,
                                         const unsigned long *dst_pfns,
                                         unsigned long start,
                                         unsigned long end,
                                         void *private)
{
        struct nouveau_dmem_fault *fault = private;
        struct nouveau_drm *drm = fault->drm;

        if (fault->fence) {
                nouveau_fence_wait(fault->fence, true, false);
                nouveau_fence_unref(&fault->fence);
        } else {
                /*
                 * FIXME wait for channel to be IDLE before calling finalizing
                 * the hmem object below (nouveau_migrate_hmem_fini()).
                 */
        }

        while (fault->npages--) {
                dma_unmap_page(drm->dev->dev, fault->dma[fault->npages],
                               PAGE_SIZE, PCI_DMA_BIDIRECTIONAL);
        }
        kfree(fault->dma);
}

static const struct migrate_vma_ops nouveau_dmem_fault_migrate_ops = {
        .alloc_and_copy         = nouveau_dmem_fault_alloc_and_copy,
        .finalize_and_map       = nouveau_dmem_fault_finalize_and_map,
};

static vm_fault_t
nouveau_dmem_fault(struct hmm_devmem *devmem,
                   struct vm_area_struct *vma,
                   unsigned long addr,
                   const struct page *page,
                   unsigned int flags,
                   pmd_t *pmdp)
{
        struct drm_device *drm_dev = dev_get_drvdata(devmem->device);
        unsigned long src[1] = {0}, dst[1] = {0};
        struct nouveau_dmem_fault fault = {0};
        int ret;



        /*
         * FIXME what we really want is to find some heuristic to migrate more
         * than just one page on CPU fault. When such fault happens it is very
         * likely that more surrounding page will CPU fault too.
         */
        fault.drm = nouveau_drm(drm_dev);
        ret = migrate_vma(&nouveau_dmem_fault_migrate_ops, vma, addr,
                          addr + PAGE_SIZE, src, dst, &fault);
        if (ret)
                return VM_FAULT_SIGBUS;

        if (dst[0] == MIGRATE_PFN_ERROR)
                return VM_FAULT_SIGBUS;

        return 0;
}

static const struct hmm_devmem_ops
nouveau_dmem_devmem_ops = {
        .free = nouveau_dmem_free,
        .fault = nouveau_dmem_fault,
};

static int
nouveau_dmem_chunk_alloc(struct nouveau_drm *drm)
{
        struct nouveau_dmem_chunk *chunk;
        int ret;

        if (drm->dmem == NULL)
                return -EINVAL;

        mutex_lock(&drm->dmem->mutex);
        chunk = list_first_entry_or_null(&drm->dmem->chunk_empty,
                                         struct nouveau_dmem_chunk,
                                         list);
        if (chunk == NULL) {
                mutex_unlock(&drm->dmem->mutex);
                return -ENOMEM;
        }

        list_del(&chunk->list);
        mutex_unlock(&drm->dmem->mutex);

        ret = nouveau_bo_new(&drm->client, DMEM_CHUNK_SIZE, 0,
                             TTM_PL_FLAG_VRAM, 0, 0, NULL, NULL,
                             &chunk->bo);
        if (ret)
                goto out;

        ret = nouveau_bo_pin(chunk->bo, TTM_PL_FLAG_VRAM, false);
        if (ret) {
                nouveau_bo_ref(NULL, &chunk->bo);
                goto out;
        }

        bitmap_zero(chunk->bitmap, DMEM_CHUNK_NPAGES);
        spin_lock_init(&chunk->lock);

out:
        mutex_lock(&drm->dmem->mutex);
        if (chunk->bo)
                list_add(&chunk->list, &drm->dmem->chunk_empty);
        else
                list_add_tail(&chunk->list, &drm->dmem->chunk_empty);
        mutex_unlock(&drm->dmem->mutex);

        return ret;
}

static struct nouveau_dmem_chunk *
nouveau_dmem_chunk_first_free_locked(struct nouveau_drm *drm)
{
        struct nouveau_dmem_chunk *chunk;

        chunk = list_first_entry_or_null(&drm->dmem->chunk_free,
                                         struct nouveau_dmem_chunk,
                                         list);
        if (chunk)
                return chunk;

        chunk = list_first_entry_or_null(&drm->dmem->chunk_empty,
                                         struct nouveau_dmem_chunk,
                                         list);
        if (chunk->bo)
                return chunk;

        return NULL;
}

static int
nouveau_dmem_pages_alloc(struct nouveau_drm *drm,
                         unsigned long npages,
                         unsigned long *pages)
{
        struct nouveau_dmem_chunk *chunk;
        unsigned long c;
        int ret;

        memset(pages, 0xff, npages * sizeof(*pages));

        mutex_lock(&drm->dmem->mutex);
        for (c = 0; c < npages;) {
                unsigned long i;

                chunk = nouveau_dmem_chunk_first_free_locked(drm);
                if (chunk == NULL) {
                        mutex_unlock(&drm->dmem->mutex);
                        ret = nouveau_dmem_chunk_alloc(drm);
                        if (ret) {
                                if (c)
                                        break;
                                return ret;
                        }
                        continue;
                }

                spin_lock(&chunk->lock);
                i = find_first_zero_bit(chunk->bitmap, DMEM_CHUNK_NPAGES);
                while (i < DMEM_CHUNK_NPAGES && c < npages) {
                        pages[c] = chunk->pfn_first + i;
                        set_bit(i, chunk->bitmap);
                        chunk->callocated++;
                        c++;

                        i = find_next_zero_bit(chunk->bitmap,
                                        DMEM_CHUNK_NPAGES, i);
                }
                spin_unlock(&chunk->lock);
        }
        mutex_unlock(&drm->dmem->mutex);

        return 0;
}

static struct page *
nouveau_dmem_page_alloc_locked(struct nouveau_drm *drm)
{
        unsigned long pfns[1];
        struct page *page;
        int ret;

        /* FIXME stop all the miss-match API ... */
        ret = nouveau_dmem_pages_alloc(drm, 1, pfns);
        if (ret)
                return NULL;

        page = pfn_to_page(pfns[0]);
        get_page(page);
        lock_page(page);
        return page;
}

static void
nouveau_dmem_page_free_locked(struct nouveau_drm *drm, struct page *page)
{
        unlock_page(page);
        put_page(page);
}

void
nouveau_dmem_resume(struct nouveau_drm *drm)
{
        struct nouveau_dmem_chunk *chunk;
        int ret;

        if (drm->dmem == NULL)
                return;

        mutex_lock(&drm->dmem->mutex);
        list_for_each_entry (chunk, &drm->dmem->chunk_free, list) {
                ret = nouveau_bo_pin(chunk->bo, TTM_PL_FLAG_VRAM, false);
                /* FIXME handle pin failure */
                WARN_ON(ret);
        }
        list_for_each_entry (chunk, &drm->dmem->chunk_full, list) {
                ret = nouveau_bo_pin(chunk->bo, TTM_PL_FLAG_VRAM, false);
                /* FIXME handle pin failure */
                WARN_ON(ret);
        }
        mutex_unlock(&drm->dmem->mutex);
}

void
nouveau_dmem_suspend(struct nouveau_drm *drm)
{
        struct nouveau_dmem_chunk *chunk;

        if (drm->dmem == NULL)
                return;

        mutex_lock(&drm->dmem->mutex);
        list_for_each_entry (chunk, &drm->dmem->chunk_free, list) {
                nouveau_bo_unpin(chunk->bo);
        }
        list_for_each_entry (chunk, &drm->dmem->chunk_full, list) {
                nouveau_bo_unpin(chunk->bo);
        }
        mutex_unlock(&drm->dmem->mutex);
}

void
nouveau_dmem_fini(struct nouveau_drm *drm)
{
        struct nouveau_dmem_chunk *chunk, *tmp;

        if (drm->dmem == NULL)
                return;

        mutex_lock(&drm->dmem->mutex);

        WARN_ON(!list_empty(&drm->dmem->chunk_free));
        WARN_ON(!list_empty(&drm->dmem->chunk_full));

        list_for_each_entry_safe (chunk, tmp, &drm->dmem->chunk_empty, list) {
                if (chunk->bo) {
                        nouveau_bo_unpin(chunk->bo);
                        nouveau_bo_ref(NULL, &chunk->bo);
                }
                list_del(&chunk->list);
                kfree(chunk);
        }

        mutex_unlock(&drm->dmem->mutex);
}

static int
nvc0b5_migrate_copy(struct nouveau_drm *drm, u64 npages,
                    enum nouveau_aper dst_aper, u64 dst_addr,
                    enum nouveau_aper src_aper, u64 src_addr)
{
        struct nouveau_channel *chan = drm->dmem->migrate.chan;
        u32 launch_dma = (1 << 9) /* MULTI_LINE_ENABLE. */ |
                         (1 << 8) /* DST_MEMORY_LAYOUT_PITCH. */ |
                         (1 << 7) /* SRC_MEMORY_LAYOUT_PITCH. */ |
                         (1 << 2) /* FLUSH_ENABLE_TRUE. */ |
                         (2 << 0) /* DATA_TRANSFER_TYPE_NON_PIPELINED. */;
        int ret;

        ret = RING_SPACE(chan, 13);
        if (ret)
                return ret;

        if (src_aper != NOUVEAU_APER_VIRT) {
                switch (src_aper) {
                case NOUVEAU_APER_VRAM:
                        BEGIN_IMC0(chan, NvSubCopy, 0x0260, 0);
                        break;
                case NOUVEAU_APER_HOST:
                        BEGIN_IMC0(chan, NvSubCopy, 0x0260, 1);
                        break;
                default:
                        return -EINVAL;
                }
                launch_dma |= 0x00001000; /* SRC_TYPE_PHYSICAL. */
        }

        if (dst_aper != NOUVEAU_APER_VIRT) {
                switch (dst_aper) {
                case NOUVEAU_APER_VRAM:
                        BEGIN_IMC0(chan, NvSubCopy, 0x0264, 0);
                        break;
                case NOUVEAU_APER_HOST:
                        BEGIN_IMC0(chan, NvSubCopy, 0x0264, 1);
                        break;
                default:
                        return -EINVAL;
                }
                launch_dma |= 0x00002000; /* DST_TYPE_PHYSICAL. */
        }

        BEGIN_NVC0(chan, NvSubCopy, 0x0400, 8);
        OUT_RING  (chan, upper_32_bits(src_addr));
        OUT_RING  (chan, lower_32_bits(src_addr));
        OUT_RING  (chan, upper_32_bits(dst_addr));
        OUT_RING  (chan, lower_32_bits(dst_addr));
        OUT_RING  (chan, PAGE_SIZE);
        OUT_RING  (chan, PAGE_SIZE);
        OUT_RING  (chan, PAGE_SIZE);
        OUT_RING  (chan, npages);
        BEGIN_NVC0(chan, NvSubCopy, 0x0300, 1);
        OUT_RING  (chan, launch_dma);
        return 0;
}

static int
nouveau_dmem_migrate_init(struct nouveau_drm *drm)
{
        switch (drm->ttm.copy.oclass) {
        case PASCAL_DMA_COPY_A:
        case PASCAL_DMA_COPY_B:
        case  VOLTA_DMA_COPY_A:
        case TURING_DMA_COPY_A:
                drm->dmem->migrate.copy_func = nvc0b5_migrate_copy;
                drm->dmem->migrate.chan = drm->ttm.chan;
                return 0;
        default:
                break;
        }
        return -ENODEV;
}

void
nouveau_dmem_init(struct nouveau_drm *drm)
{
        struct device *device = drm->dev->dev;
        unsigned long i, size;
        int ret;

        /* This only make sense on PASCAL or newer */
        if (drm->client.device.info.family < NV_DEVICE_INFO_V0_PASCAL)
                return;

        if (!(drm->dmem = kzalloc(sizeof(*drm->dmem), GFP_KERNEL)))
                return;

        mutex_init(&drm->dmem->mutex);
        INIT_LIST_HEAD(&drm->dmem->chunk_free);
        INIT_LIST_HEAD(&drm->dmem->chunk_full);
        INIT_LIST_HEAD(&drm->dmem->chunk_empty);

        size = ALIGN(drm->client.device.info.ram_user, DMEM_CHUNK_SIZE);

        /* Initialize migration dma helpers before registering memory */
        ret = nouveau_dmem_migrate_init(drm);
        if (ret) {
                kfree(drm->dmem);
                drm->dmem = NULL;
                return;
        }

        /*
         * FIXME we need some kind of policy to decide how much VRAM we
         * want to register with HMM. For now just register everything
         * and latter if we want to do thing like over commit then we
         * could revisit this.
         */
        drm->dmem->devmem = hmm_devmem_add(&nouveau_dmem_devmem_ops,
                                           device, size);
        if (IS_ERR(drm->dmem->devmem)) {
                kfree(drm->dmem);
                drm->dmem = NULL;
                return;
        }

        for (i = 0; i < (size / DMEM_CHUNK_SIZE); ++i) {
                struct nouveau_dmem_chunk *chunk;
                struct page *page;
                unsigned long j;

                chunk = kzalloc(sizeof(*chunk), GFP_KERNEL);
                if (chunk == NULL) {
                        nouveau_dmem_fini(drm);
                        return;
                }

                chunk->drm = drm;
                chunk->pfn_first = drm->dmem->devmem->pfn_first;
                chunk->pfn_first += (i * DMEM_CHUNK_NPAGES);
                list_add_tail(&chunk->list, &drm->dmem->chunk_empty);

                page = pfn_to_page(chunk->pfn_first);
                for (j = 0; j < DMEM_CHUNK_NPAGES; ++j, ++page) {
                        hmm_devmem_page_set_drvdata(page, (long)chunk);
                }
        }

        NV_INFO(drm, "DMEM: registered %ldMB of device memory\n", size >> 20);
}

static void
nouveau_dmem_migrate_alloc_and_copy(struct vm_area_struct *vma,
                                    const unsigned long *src_pfns,
                                    unsigned long *dst_pfns,
                                    unsigned long start,
                                    unsigned long end,
                                    void *private)
{
        struct nouveau_migrate *migrate = private;
        struct nouveau_drm *drm = migrate->drm;
        struct device *dev = drm->dev->dev;
        unsigned long addr, i, npages = 0;
        nouveau_migrate_copy_t copy;
        int ret;

        /* First allocate new memory */
        for (addr = start, i = 0; addr < end; addr += PAGE_SIZE, i++) {
                struct page *dpage, *spage;

                dst_pfns[i] = 0;
                spage = migrate_pfn_to_page(src_pfns[i]);
                if (!spage || !(src_pfns[i] & MIGRATE_PFN_MIGRATE))
                        continue;

                dpage = nouveau_dmem_page_alloc_locked(drm);
                if (!dpage)
                        continue;

                dst_pfns[i] = migrate_pfn(page_to_pfn(dpage)) |
                              MIGRATE_PFN_LOCKED |
                              MIGRATE_PFN_DEVICE;
                npages++;
        }

        if (!npages)
                return;

        /* Allocate storage for DMA addresses, so we can unmap later. */
        migrate->dma = kmalloc(sizeof(*migrate->dma) * npages, GFP_KERNEL);
        if (!migrate->dma)
                goto error;

        /* Copy things over */
        copy = drm->dmem->migrate.copy_func;
        for (addr = start, i = 0; addr < end; addr += PAGE_SIZE, i++) {
                struct nouveau_dmem_chunk *chunk;
                struct page *spage, *dpage;
                u64 src_addr, dst_addr;

                dpage = migrate_pfn_to_page(dst_pfns[i]);
                if (!dpage || dst_pfns[i] == MIGRATE_PFN_ERROR)
                        continue;

                chunk = (void *)hmm_devmem_page_get_drvdata(dpage);
                dst_addr = page_to_pfn(dpage) - chunk->pfn_first;
                dst_addr = (dst_addr << PAGE_SHIFT) + chunk->bo->bo.offset;

                spage = migrate_pfn_to_page(src_pfns[i]);
                if (!spage || !(src_pfns[i] & MIGRATE_PFN_MIGRATE)) {
                        nouveau_dmem_page_free_locked(drm, dpage);
                        dst_pfns[i] = 0;
                        continue;
                }

                migrate->dma[migrate->dma_nr] =
                        dma_map_page_attrs(dev, spage, 0, PAGE_SIZE,
                                           PCI_DMA_BIDIRECTIONAL,
                                           DMA_ATTR_SKIP_CPU_SYNC);
                if (dma_mapping_error(dev, migrate->dma[migrate->dma_nr])) {
                        nouveau_dmem_page_free_locked(drm, dpage);
                        dst_pfns[i] = 0;
                        continue;
                }

                src_addr = migrate->dma[migrate->dma_nr++];

                ret = copy(drm, 1, NOUVEAU_APER_VRAM, dst_addr,
                                   NOUVEAU_APER_HOST, src_addr);
                if (ret) {
                        nouveau_dmem_page_free_locked(drm, dpage);
                        dst_pfns[i] = 0;
                        continue;
                }
        }

        nouveau_fence_new(drm->dmem->migrate.chan, false, &migrate->fence);

        return;

error:
        for (addr = start, i = 0; addr < end; addr += PAGE_SIZE, ++i) {
                struct page *page;

                if (!dst_pfns[i] || dst_pfns[i] == MIGRATE_PFN_ERROR)
                        continue;

                page = migrate_pfn_to_page(dst_pfns[i]);
                dst_pfns[i] = MIGRATE_PFN_ERROR;
                if (page == NULL)
                        continue;

                __free_page(page);
        }
}

void nouveau_dmem_migrate_finalize_and_map(struct vm_area_struct *vma,
                                           const unsigned long *src_pfns,
                                           const unsigned long *dst_pfns,
                                           unsigned long start,
                                           unsigned long end,
                                           void *private)
{
        struct nouveau_migrate *migrate = private;
        struct nouveau_drm *drm = migrate->drm;

        if (migrate->fence) {
                nouveau_fence_wait(migrate->fence, true, false);
                nouveau_fence_unref(&migrate->fence);
        } else {
                /*
                 * FIXME wait for channel to be IDLE before finalizing
                 * the hmem object below (nouveau_migrate_hmem_fini()) ?
                 */
        }

        while (migrate->dma_nr--) {
                dma_unmap_page(drm->dev->dev, migrate->dma[migrate->dma_nr],
                               PAGE_SIZE, PCI_DMA_BIDIRECTIONAL);
        }
        kfree(migrate->dma);

        /*
         * FIXME optimization: update GPU page table to point to newly
         * migrated memory.
         */
}

static const struct migrate_vma_ops nouveau_dmem_migrate_ops = {
        .alloc_and_copy         = nouveau_dmem_migrate_alloc_and_copy,
        .finalize_and_map       = nouveau_dmem_migrate_finalize_and_map,
};

int
nouveau_dmem_migrate_vma(struct nouveau_drm *drm,
                         struct vm_area_struct *vma,
                         unsigned long start,
                         unsigned long end)
{
        unsigned long *src_pfns, *dst_pfns, npages;
        struct nouveau_migrate migrate = {0};
        unsigned long i, c, max;
        int ret = 0;

        npages = (end - start) >> PAGE_SHIFT;
        max = min(SG_MAX_SINGLE_ALLOC, npages);
        src_pfns = kzalloc(sizeof(long) * max, GFP_KERNEL);
        if (src_pfns == NULL)
                return -ENOMEM;
        dst_pfns = kzalloc(sizeof(long) * max, GFP_KERNEL);
        if (dst_pfns == NULL) {
                kfree(src_pfns);
                return -ENOMEM;
        }

        migrate.drm = drm;
        migrate.vma = vma;
        migrate.npages = npages;
        for (i = 0; i < npages; i += c) {
                unsigned long next;

                c = min(SG_MAX_SINGLE_ALLOC, npages);
                next = start + (c << PAGE_SHIFT);
                ret = migrate_vma(&nouveau_dmem_migrate_ops, vma, start,
                                  next, src_pfns, dst_pfns, &migrate);
                if (ret)
                        goto out;
                start = next;
        }

out:
        kfree(dst_pfns);
        kfree(src_pfns);
        return ret;
}

static inline bool
nouveau_dmem_page(struct nouveau_drm *drm, struct page *page)
{
        if (!is_device_private_page(page))
                return false;

        if (drm->dmem->devmem != page->pgmap->data)
                return false;

        return true;
}

void
nouveau_dmem_convert_pfn(struct nouveau_drm *drm,
                         struct hmm_range *range)
{
        unsigned long i, npages;

        npages = (range->end - range->start) >> PAGE_SHIFT;
        for (i = 0; i < npages; ++i) {
                struct nouveau_dmem_chunk *chunk;
                struct page *page;
                uint64_t addr;

                page = hmm_pfn_to_page(range, range->pfns[i]);
                if (page == NULL)
                        continue;

                if (!(range->pfns[i] & range->flags[HMM_PFN_DEVICE_PRIVATE])) {
                        continue;
                }

                if (!nouveau_dmem_page(drm, page)) {
                        WARN(1, "Some unknown device memory !\n");
                        range->pfns[i] = 0;
                        continue;
                }

                chunk = (void *)hmm_devmem_page_get_drvdata(page);
                addr = page_to_pfn(page) - chunk->pfn_first;
                addr = (addr + chunk->bo->bo.mem.start) << PAGE_SHIFT;

                range->pfns[i] &= ((1UL << range->pfn_shift) - 1);
                range->pfns[i] |= (addr >> PAGE_SHIFT) << range->pfn_shift;
        }
}