ttm_bo_vm.c

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/**************************************************************************
 *
 * 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 <ttm/ttm_module.h>
#include <ttm/ttm_bo_driver.h>
#include <ttm/ttm_placement.h>
#include <linux/mm.h>
#include <linux/rbtree.h>
#include <linux/module.h>
#include <linux/uaccess.h>

#define TTM_BO_VM_NUM_PREFAULT 16

static struct ttm_buffer_object *ttm_bo_vm_lookup_rb(struct ttm_bo_device *bdev,
                             unsigned long page_start,
                             unsigned long num_pages)
{
    struct rb_node *cur = bdev->addr_space_rb.rb_node;
    unsigned long cur_offset;
    struct ttm_buffer_object *bo;
    struct ttm_buffer_object *best_bo = NULL;

    while (likely(cur != NULL)) {
        bo = rb_entry(cur, struct ttm_buffer_object, vm_rb);
        cur_offset = bo->vm_node->start;
        if (page_start >= cur_offset) {
            cur = cur->rb_right;
            best_bo = bo;
            if (page_start == cur_offset)
                break;
        } else
            cur = cur->rb_left;
    }

    if (unlikely(best_bo == NULL))
        return NULL;

    if (unlikely((best_bo->vm_node->start + best_bo->num_pages) <
             (page_start + num_pages)))
        return NULL;

    return best_bo;
}

static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
    struct ttm_buffer_object *bo = (struct ttm_buffer_object *)
        vma->vm_private_data;
    struct ttm_bo_device *bdev = bo->bdev;
    unsigned long page_offset;
    unsigned long page_last;
    unsigned long pfn;
    struct ttm_tt *ttm = NULL;
    struct page *page;
    int ret;
    int i;
    unsigned long address = (unsigned long)vmf->virtual_address;
    int retval = VM_FAULT_NOPAGE;
    struct ttm_mem_type_manager *man =
        &bdev->man[bo->mem.mem_type];

    /*
     * Work around locking order reversal in fault / nopfn
     * between mmap_sem and bo_reserve: Perform a trylock operation
     * for reserve, and if it fails, retry the fault after scheduling.
     */

    ret = ttm_bo_reserve(bo, true, true, false, 0);
    if (unlikely(ret != 0)) {
        if (ret == -EBUSY)
            set_need_resched();
        return VM_FAULT_NOPAGE;
    }

    if (bdev->driver->fault_reserve_notify) {
        ret = bdev->driver->fault_reserve_notify(bo);
        switch (ret) {
        case 0:
            break;
        case -EBUSY:
            set_need_resched();
        case -ERESTARTSYS:
            retval = VM_FAULT_NOPAGE;
            goto out_unlock;
        default:
            retval = VM_FAULT_SIGBUS;
            goto out_unlock;
        }
    }

    /*
     * Wait for buffer data in transit, due to a pipelined
     * move.
     */

    spin_lock(&bdev->fence_lock);
    if (test_bit(TTM_BO_PRIV_FLAG_MOVING, &bo->priv_flags)) {
        ret = ttm_bo_wait(bo, false, true, false);
        spin_unlock(&bdev->fence_lock);
        if (unlikely(ret != 0)) {
            retval = (ret != -ERESTARTSYS) ?
                VM_FAULT_SIGBUS : VM_FAULT_NOPAGE;
            goto out_unlock;
        }
    } else
        spin_unlock(&bdev->fence_lock);

    ret = ttm_mem_io_lock(man, true);
    if (unlikely(ret != 0)) {
        retval = VM_FAULT_NOPAGE;
        goto out_unlock;
    }
    ret = ttm_mem_io_reserve_vm(bo);
    if (unlikely(ret != 0)) {
        retval = VM_FAULT_SIGBUS;
        goto out_io_unlock;
    }

    page_offset = ((address - vma->vm_start) >> PAGE_SHIFT) +
        bo->vm_node->start - vma->vm_pgoff;
    page_last = ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) +
        bo->vm_node->start - vma->vm_pgoff;

    if (unlikely(page_offset >= bo->num_pages)) {
        retval = VM_FAULT_SIGBUS;
        goto out_io_unlock;
    }

    /*
     * Strictly, we're not allowed to modify vma->vm_page_prot here,
     * since the mmap_sem is only held in read mode. However, we
     * modify only the caching bits of vma->vm_page_prot and
     * consider those bits protected by
     * the bo->mutex, as we should be the only writers.
     * There shouldn't really be any readers of these bits except
     * within vm_insert_mixed()? fork?
     *
     * TODO: Add a list of vmas to the bo, and change the
     * vma->vm_page_prot when the object changes caching policy, with
     * the correct locks held.
     */
    if (bo->mem.bus.is_iomem) {
        vma->vm_page_prot = ttm_io_prot(bo->mem.placement,
                        vma->vm_page_prot);
    } else {
        ttm = bo->ttm;
        vma->vm_page_prot = (bo->mem.placement & TTM_PL_FLAG_CACHED) ?
            vm_get_page_prot(vma->vm_flags) :
            ttm_io_prot(bo->mem.placement, vma->vm_page_prot);

        /* Allocate all page at once, most common usage */
        if (ttm->bdev->driver->ttm_tt_populate(ttm)) {
            retval = VM_FAULT_OOM;
            goto out_io_unlock;
        }
    }

    /*
     * Speculatively prefault a number of pages. Only error on
     * first page.
     */
    for (i = 0; i < TTM_BO_VM_NUM_PREFAULT; ++i) {
        if (bo->mem.bus.is_iomem)
            pfn = ((bo->mem.bus.base + bo->mem.bus.offset) >> PAGE_SHIFT) + page_offset;
        else {
            page = ttm->pages[page_offset];
            if (unlikely(!page && i == 0)) {
                retval = VM_FAULT_OOM;
                goto out_io_unlock;
            } else if (unlikely(!page)) {
                break;
            }
            pfn = page_to_pfn(page);
        }

        ret = vm_insert_mixed(vma, address, pfn);
        /*
         * Somebody beat us to this PTE or prefaulting to
         * an already populated PTE, or prefaulting error.
         */

        if (unlikely((ret == -EBUSY) || (ret != 0 && i > 0)))
            break;
        else if (unlikely(ret != 0)) {
            retval =
                (ret == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS;
            goto out_io_unlock;
        }

        address += PAGE_SIZE;
        if (unlikely(++page_offset >= page_last))
            break;
    }
out_io_unlock:
    ttm_mem_io_unlock(man);
out_unlock:
    ttm_bo_unreserve(bo);
    return retval;
}

static void ttm_bo_vm_open(struct vm_area_struct *vma)
{
    struct ttm_buffer_object *bo =
        (struct ttm_buffer_object *)vma->vm_private_data;

    (void)ttm_bo_reference(bo);
}

static void ttm_bo_vm_close(struct vm_area_struct *vma)
{
    struct ttm_buffer_object *bo = (struct ttm_buffer_object *)vma->vm_private_data;

    ttm_bo_unref(&bo);
    vma->vm_private_data = NULL;
}

static const struct vm_operations_struct ttm_bo_vm_ops = {
    .fault = ttm_bo_vm_fault,
    .open = ttm_bo_vm_open,
    .close = ttm_bo_vm_close
};

int ttm_bo_mmap(struct file *filp, struct vm_area_struct *vma,
        struct ttm_bo_device *bdev)
{
    struct ttm_bo_driver *driver;
    struct ttm_buffer_object *bo;
    int ret;

    read_lock(&bdev->vm_lock);
    bo = ttm_bo_vm_lookup_rb(bdev, vma->vm_pgoff,
                 (vma->vm_end - vma->vm_start) >> PAGE_SHIFT);
    if (likely(bo != NULL))
        ttm_bo_reference(bo);
    read_unlock(&bdev->vm_lock);

    if (unlikely(bo == NULL)) {
        pr_err("Could not find buffer object to map\n");
        return -EINVAL;
    }

    driver = bo->bdev->driver;
    if (unlikely(!driver->verify_access)) {
        ret = -EPERM;
        goto out_unref;
    }
    ret = driver->verify_access(bo, filp);
    if (unlikely(ret != 0))
        goto out_unref;

    vma->vm_ops = &ttm_bo_vm_ops;

    /*
     * Note: We're transferring the bo reference to
     * vma->vm_private_data here.
     */

    vma->vm_private_data = bo;
    vma->vm_flags |= VM_IO | VM_MIXEDMAP | VM_DONTEXPAND | VM_DONTDUMP;
    return 0;
out_unref:
    ttm_bo_unref(&bo);
    return ret;
}
EXPORT_SYMBOL(ttm_bo_mmap);

int ttm_fbdev_mmap(struct vm_area_struct *vma, struct ttm_buffer_object *bo)
{
    if (vma->vm_pgoff != 0)
        return -EACCES;

    vma->vm_ops = &ttm_bo_vm_ops;
    vma->vm_private_data = ttm_bo_reference(bo);
    vma->vm_flags |= VM_IO | VM_MIXEDMAP | VM_DONTEXPAND;
    return 0;
}
EXPORT_SYMBOL(ttm_fbdev_mmap);


ssize_t ttm_bo_io(struct ttm_bo_device *bdev, struct file *filp,
          const char __user *wbuf, char __user *rbuf, size_t count,
          loff_t *f_pos, bool write)
{
    struct ttm_buffer_object *bo;
    struct ttm_bo_driver *driver;
    struct ttm_bo_kmap_obj map;
    unsigned long dev_offset = (*f_pos >> PAGE_SHIFT);
    unsigned long kmap_offset;
    unsigned long kmap_end;
    unsigned long kmap_num;
    size_t io_size;
    unsigned int page_offset;
    char *virtual;
    int ret;
    bool no_wait = false;
    bool dummy;

    read_lock(&bdev->vm_lock);
    bo = ttm_bo_vm_lookup_rb(bdev, dev_offset, 1);
    if (likely(bo != NULL))
        ttm_bo_reference(bo);
    read_unlock(&bdev->vm_lock);

    if (unlikely(bo == NULL))
        return -EFAULT;

    driver = bo->bdev->driver;
    if (unlikely(!driver->verify_access)) {
        ret = -EPERM;
        goto out_unref;
    }

    ret = driver->verify_access(bo, filp);
    if (unlikely(ret != 0))
        goto out_unref;

    kmap_offset = dev_offset - bo->vm_node->start;
    if (unlikely(kmap_offset >= bo->num_pages)) {
        ret = -EFBIG;
        goto out_unref;
    }

    page_offset = *f_pos & ~PAGE_MASK;
    io_size = bo->num_pages - kmap_offset;
    io_size = (io_size << PAGE_SHIFT) - page_offset;
    if (count < io_size)
        io_size = count;

    kmap_end = (*f_pos + count - 1) >> PAGE_SHIFT;
    kmap_num = kmap_end - kmap_offset + 1;

    ret = ttm_bo_reserve(bo, true, no_wait, false, 0);

    switch (ret) {
    case 0:
        break;
    case -EBUSY:
        ret = -EAGAIN;
        goto out_unref;
    default:
        goto out_unref;
    }

    ret = ttm_bo_kmap(bo, kmap_offset, kmap_num, &map);
    if (unlikely(ret != 0)) {
        ttm_bo_unreserve(bo);
        goto out_unref;
    }

    virtual = ttm_kmap_obj_virtual(&map, &dummy);
    virtual += page_offset;

    if (write)
        ret = copy_from_user(virtual, wbuf, io_size);
    else
        ret = copy_to_user(rbuf, virtual, io_size);

    ttm_bo_kunmap(&map);
    ttm_bo_unreserve(bo);
    ttm_bo_unref(&bo);

    if (unlikely(ret != 0))
        return -EFBIG;

    *f_pos += io_size;

    return io_size;
out_unref:
    ttm_bo_unref(&bo);
    return ret;
}

ssize_t ttm_bo_fbdev_io(struct ttm_buffer_object *bo, const char __user *wbuf,
            char __user *rbuf, size_t count, loff_t *f_pos,
            bool write)
{
    struct ttm_bo_kmap_obj map;
    unsigned long kmap_offset;
    unsigned long kmap_end;
    unsigned long kmap_num;
    size_t io_size;
    unsigned int page_offset;
    char *virtual;
    int ret;
    bool no_wait = false;
    bool dummy;

    kmap_offset = (*f_pos >> PAGE_SHIFT);
    if (unlikely(kmap_offset >= bo->num_pages))
        return -EFBIG;

    page_offset = *f_pos & ~PAGE_MASK;
    io_size = bo->num_pages - kmap_offset;
    io_size = (io_size << PAGE_SHIFT) - page_offset;
    if (count < io_size)
        io_size = count;

    kmap_end = (*f_pos + count - 1) >> PAGE_SHIFT;
    kmap_num = kmap_end - kmap_offset + 1;

    ret = ttm_bo_reserve(bo, true, no_wait, false, 0);

    switch (ret) {
    case 0:
        break;
    case -EBUSY:
        return -EAGAIN;
    default:
        return ret;
    }

    ret = ttm_bo_kmap(bo, kmap_offset, kmap_num, &map);
    if (unlikely(ret != 0)) {
        ttm_bo_unreserve(bo);
        return ret;
    }

    virtual = ttm_kmap_obj_virtual(&map, &dummy);
    virtual += page_offset;

    if (write)
        ret = copy_from_user(virtual, wbuf, io_size);
    else
        ret = copy_to_user(rbuf, virtual, io_size);

    ttm_bo_kunmap(&map);
    ttm_bo_unreserve(bo);
    ttm_bo_unref(&bo);

    if (unlikely(ret != 0))
        return ret;

    *f_pos += io_size;

    return io_size;
}