diff options
Diffstat (limited to 'kernel/drivers/xen/gntdev.c')
| -rw-r--r-- | kernel/drivers/xen/gntdev.c | 924 |
1 files changed, 924 insertions, 0 deletions
diff --git a/kernel/drivers/xen/gntdev.c b/kernel/drivers/xen/gntdev.c new file mode 100644 index 000000000..892748507 --- /dev/null +++ b/kernel/drivers/xen/gntdev.c @@ -0,0 +1,924 @@ +/****************************************************************************** + * gntdev.c + * + * Device for accessing (in user-space) pages that have been granted by other + * domains. + * + * Copyright (c) 2006-2007, D G Murray. + * (c) 2009 Gerd Hoffmann <kraxel@redhat.com> + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#undef DEBUG + +#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/miscdevice.h> +#include <linux/fs.h> +#include <linux/mm.h> +#include <linux/mman.h> +#include <linux/mmu_notifier.h> +#include <linux/types.h> +#include <linux/uaccess.h> +#include <linux/sched.h> +#include <linux/spinlock.h> +#include <linux/slab.h> +#include <linux/highmem.h> + +#include <xen/xen.h> +#include <xen/grant_table.h> +#include <xen/balloon.h> +#include <xen/gntdev.h> +#include <xen/events.h> +#include <asm/xen/hypervisor.h> +#include <asm/xen/hypercall.h> +#include <asm/xen/page.h> + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Derek G. Murray <Derek.Murray@cl.cam.ac.uk>, " + "Gerd Hoffmann <kraxel@redhat.com>"); +MODULE_DESCRIPTION("User-space granted page access driver"); + +static int limit = 1024*1024; +module_param(limit, int, 0644); +MODULE_PARM_DESC(limit, "Maximum number of grants that may be mapped by " + "the gntdev device"); + +static atomic_t pages_mapped = ATOMIC_INIT(0); + +static int use_ptemod; +#define populate_freeable_maps use_ptemod + +struct gntdev_priv { + /* maps with visible offsets in the file descriptor */ + struct list_head maps; + /* maps that are not visible; will be freed on munmap. + * Only populated if populate_freeable_maps == 1 */ + struct list_head freeable_maps; + /* lock protects maps and freeable_maps */ + struct mutex lock; + struct mm_struct *mm; + struct mmu_notifier mn; +}; + +struct unmap_notify { + int flags; + /* Address relative to the start of the grant_map */ + int addr; + int event; +}; + +struct grant_map { + struct list_head next; + struct vm_area_struct *vma; + int index; + int count; + int flags; + atomic_t users; + struct unmap_notify notify; + struct ioctl_gntdev_grant_ref *grants; + struct gnttab_map_grant_ref *map_ops; + struct gnttab_unmap_grant_ref *unmap_ops; + struct gnttab_map_grant_ref *kmap_ops; + struct gnttab_unmap_grant_ref *kunmap_ops; + struct page **pages; + unsigned long pages_vm_start; +}; + +static int unmap_grant_pages(struct grant_map *map, int offset, int pages); + +/* ------------------------------------------------------------------ */ + +static void gntdev_print_maps(struct gntdev_priv *priv, + char *text, int text_index) +{ +#ifdef DEBUG + struct grant_map *map; + + pr_debug("%s: maps list (priv %p)\n", __func__, priv); + list_for_each_entry(map, &priv->maps, next) + pr_debug(" index %2d, count %2d %s\n", + map->index, map->count, + map->index == text_index && text ? text : ""); +#endif +} + +static void gntdev_free_map(struct grant_map *map) +{ + if (map == NULL) + return; + + if (map->pages) + gnttab_free_pages(map->count, map->pages); + kfree(map->pages); + kfree(map->grants); + kfree(map->map_ops); + kfree(map->unmap_ops); + kfree(map->kmap_ops); + kfree(map->kunmap_ops); + kfree(map); +} + +static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count) +{ + struct grant_map *add; + int i; + + add = kzalloc(sizeof(struct grant_map), GFP_KERNEL); + if (NULL == add) + return NULL; + + add->grants = kcalloc(count, sizeof(add->grants[0]), GFP_KERNEL); + add->map_ops = kcalloc(count, sizeof(add->map_ops[0]), GFP_KERNEL); + add->unmap_ops = kcalloc(count, sizeof(add->unmap_ops[0]), GFP_KERNEL); + add->kmap_ops = kcalloc(count, sizeof(add->kmap_ops[0]), GFP_KERNEL); + add->kunmap_ops = kcalloc(count, sizeof(add->kunmap_ops[0]), GFP_KERNEL); + add->pages = kcalloc(count, sizeof(add->pages[0]), GFP_KERNEL); + if (NULL == add->grants || + NULL == add->map_ops || + NULL == add->unmap_ops || + NULL == add->kmap_ops || + NULL == add->kunmap_ops || + NULL == add->pages) + goto err; + + if (gnttab_alloc_pages(count, add->pages)) + goto err; + + for (i = 0; i < count; i++) { + add->map_ops[i].handle = -1; + add->unmap_ops[i].handle = -1; + add->kmap_ops[i].handle = -1; + add->kunmap_ops[i].handle = -1; + } + + add->index = 0; + add->count = count; + atomic_set(&add->users, 1); + + return add; + +err: + gntdev_free_map(add); + return NULL; +} + +static void gntdev_add_map(struct gntdev_priv *priv, struct grant_map *add) +{ + struct grant_map *map; + + list_for_each_entry(map, &priv->maps, next) { + if (add->index + add->count < map->index) { + list_add_tail(&add->next, &map->next); + goto done; + } + add->index = map->index + map->count; + } + list_add_tail(&add->next, &priv->maps); + +done: + gntdev_print_maps(priv, "[new]", add->index); +} + +static struct grant_map *gntdev_find_map_index(struct gntdev_priv *priv, + int index, int count) +{ + struct grant_map *map; + + list_for_each_entry(map, &priv->maps, next) { + if (map->index != index) + continue; + if (count && map->count != count) + continue; + return map; + } + return NULL; +} + +static void gntdev_put_map(struct gntdev_priv *priv, struct grant_map *map) +{ + if (!map) + return; + + if (!atomic_dec_and_test(&map->users)) + return; + + atomic_sub(map->count, &pages_mapped); + + if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) { + notify_remote_via_evtchn(map->notify.event); + evtchn_put(map->notify.event); + } + + if (populate_freeable_maps && priv) { + mutex_lock(&priv->lock); + list_del(&map->next); + mutex_unlock(&priv->lock); + } + + if (map->pages && !use_ptemod) + unmap_grant_pages(map, 0, map->count); + gntdev_free_map(map); +} + +/* ------------------------------------------------------------------ */ + +static int find_grant_ptes(pte_t *pte, pgtable_t token, + unsigned long addr, void *data) +{ + struct grant_map *map = data; + unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT; + int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte; + u64 pte_maddr; + + BUG_ON(pgnr >= map->count); + pte_maddr = arbitrary_virt_to_machine(pte).maddr; + + /* + * Set the PTE as special to force get_user_pages_fast() fall + * back to the slow path. If this is not supported as part of + * the grant map, it will be done afterwards. + */ + if (xen_feature(XENFEAT_gnttab_map_avail_bits)) + flags |= (1 << _GNTMAP_guest_avail0); + + gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags, + map->grants[pgnr].ref, + map->grants[pgnr].domid); + gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags, + -1 /* handle */); + return 0; +} + +#ifdef CONFIG_X86 +static int set_grant_ptes_as_special(pte_t *pte, pgtable_t token, + unsigned long addr, void *data) +{ + set_pte_at(current->mm, addr, pte, pte_mkspecial(*pte)); + return 0; +} +#endif + +static int map_grant_pages(struct grant_map *map) +{ + int i, err = 0; + + if (!use_ptemod) { + /* Note: it could already be mapped */ + if (map->map_ops[0].handle != -1) + return 0; + for (i = 0; i < map->count; i++) { + unsigned long addr = (unsigned long) + pfn_to_kaddr(page_to_pfn(map->pages[i])); + gnttab_set_map_op(&map->map_ops[i], addr, map->flags, + map->grants[i].ref, + map->grants[i].domid); + gnttab_set_unmap_op(&map->unmap_ops[i], addr, + map->flags, -1 /* handle */); + } + } else { + /* + * Setup the map_ops corresponding to the pte entries pointing + * to the kernel linear addresses of the struct pages. + * These ptes are completely different from the user ptes dealt + * with find_grant_ptes. + */ + for (i = 0; i < map->count; i++) { + unsigned long address = (unsigned long) + pfn_to_kaddr(page_to_pfn(map->pages[i])); + BUG_ON(PageHighMem(map->pages[i])); + + gnttab_set_map_op(&map->kmap_ops[i], address, + map->flags | GNTMAP_host_map, + map->grants[i].ref, + map->grants[i].domid); + gnttab_set_unmap_op(&map->kunmap_ops[i], address, + map->flags | GNTMAP_host_map, -1); + } + } + + pr_debug("map %d+%d\n", map->index, map->count); + err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL, + map->pages, map->count); + if (err) + return err; + + for (i = 0; i < map->count; i++) { + if (map->map_ops[i].status) { + err = -EINVAL; + continue; + } + + map->unmap_ops[i].handle = map->map_ops[i].handle; + if (use_ptemod) + map->kunmap_ops[i].handle = map->kmap_ops[i].handle; + } + return err; +} + +static int __unmap_grant_pages(struct grant_map *map, int offset, int pages) +{ + int i, err = 0; + struct gntab_unmap_queue_data unmap_data; + + if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) { + int pgno = (map->notify.addr >> PAGE_SHIFT); + if (pgno >= offset && pgno < offset + pages) { + /* No need for kmap, pages are in lowmem */ + uint8_t *tmp = pfn_to_kaddr(page_to_pfn(map->pages[pgno])); + tmp[map->notify.addr & (PAGE_SIZE-1)] = 0; + map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE; + } + } + + unmap_data.unmap_ops = map->unmap_ops + offset; + unmap_data.kunmap_ops = use_ptemod ? map->kunmap_ops + offset : NULL; + unmap_data.pages = map->pages + offset; + unmap_data.count = pages; + + err = gnttab_unmap_refs_sync(&unmap_data); + if (err) + return err; + + for (i = 0; i < pages; i++) { + if (map->unmap_ops[offset+i].status) + err = -EINVAL; + pr_debug("unmap handle=%d st=%d\n", + map->unmap_ops[offset+i].handle, + map->unmap_ops[offset+i].status); + map->unmap_ops[offset+i].handle = -1; + } + return err; +} + +static int unmap_grant_pages(struct grant_map *map, int offset, int pages) +{ + int range, err = 0; + + pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages); + + /* It is possible the requested range will have a "hole" where we + * already unmapped some of the grants. Only unmap valid ranges. + */ + while (pages && !err) { + while (pages && map->unmap_ops[offset].handle == -1) { + offset++; + pages--; + } + range = 0; + while (range < pages) { + if (map->unmap_ops[offset+range].handle == -1) { + range--; + break; + } + range++; + } + err = __unmap_grant_pages(map, offset, range); + offset += range; + pages -= range; + } + + return err; +} + +/* ------------------------------------------------------------------ */ + +static void gntdev_vma_open(struct vm_area_struct *vma) +{ + struct grant_map *map = vma->vm_private_data; + + pr_debug("gntdev_vma_open %p\n", vma); + atomic_inc(&map->users); +} + +static void gntdev_vma_close(struct vm_area_struct *vma) +{ + struct grant_map *map = vma->vm_private_data; + struct file *file = vma->vm_file; + struct gntdev_priv *priv = file->private_data; + + pr_debug("gntdev_vma_close %p\n", vma); + if (use_ptemod) { + /* It is possible that an mmu notifier could be running + * concurrently, so take priv->lock to ensure that the vma won't + * vanishing during the unmap_grant_pages call, since we will + * spin here until that completes. Such a concurrent call will + * not do any unmapping, since that has been done prior to + * closing the vma, but it may still iterate the unmap_ops list. + */ + mutex_lock(&priv->lock); + map->vma = NULL; + mutex_unlock(&priv->lock); + } + vma->vm_private_data = NULL; + gntdev_put_map(priv, map); +} + +static struct page *gntdev_vma_find_special_page(struct vm_area_struct *vma, + unsigned long addr) +{ + struct grant_map *map = vma->vm_private_data; + + return map->pages[(addr - map->pages_vm_start) >> PAGE_SHIFT]; +} + +static struct vm_operations_struct gntdev_vmops = { + .open = gntdev_vma_open, + .close = gntdev_vma_close, + .find_special_page = gntdev_vma_find_special_page, +}; + +/* ------------------------------------------------------------------ */ + +static void unmap_if_in_range(struct grant_map *map, + unsigned long start, unsigned long end) +{ + unsigned long mstart, mend; + int err; + + if (!map->vma) + return; + if (map->vma->vm_start >= end) + return; + if (map->vma->vm_end <= start) + return; + mstart = max(start, map->vma->vm_start); + mend = min(end, map->vma->vm_end); + pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n", + map->index, map->count, + map->vma->vm_start, map->vma->vm_end, + start, end, mstart, mend); + err = unmap_grant_pages(map, + (mstart - map->vma->vm_start) >> PAGE_SHIFT, + (mend - mstart) >> PAGE_SHIFT); + WARN_ON(err); +} + +static void mn_invl_range_start(struct mmu_notifier *mn, + struct mm_struct *mm, + unsigned long start, unsigned long end) +{ + struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn); + struct grant_map *map; + + mutex_lock(&priv->lock); + list_for_each_entry(map, &priv->maps, next) { + unmap_if_in_range(map, start, end); + } + list_for_each_entry(map, &priv->freeable_maps, next) { + unmap_if_in_range(map, start, end); + } + mutex_unlock(&priv->lock); +} + +static void mn_invl_page(struct mmu_notifier *mn, + struct mm_struct *mm, + unsigned long address) +{ + mn_invl_range_start(mn, mm, address, address + PAGE_SIZE); +} + +static void mn_release(struct mmu_notifier *mn, + struct mm_struct *mm) +{ + struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn); + struct grant_map *map; + int err; + + mutex_lock(&priv->lock); + list_for_each_entry(map, &priv->maps, next) { + if (!map->vma) + continue; + pr_debug("map %d+%d (%lx %lx)\n", + map->index, map->count, + map->vma->vm_start, map->vma->vm_end); + err = unmap_grant_pages(map, /* offset */ 0, map->count); + WARN_ON(err); + } + list_for_each_entry(map, &priv->freeable_maps, next) { + if (!map->vma) + continue; + pr_debug("map %d+%d (%lx %lx)\n", + map->index, map->count, + map->vma->vm_start, map->vma->vm_end); + err = unmap_grant_pages(map, /* offset */ 0, map->count); + WARN_ON(err); + } + mutex_unlock(&priv->lock); +} + +static struct mmu_notifier_ops gntdev_mmu_ops = { + .release = mn_release, + .invalidate_page = mn_invl_page, + .invalidate_range_start = mn_invl_range_start, +}; + +/* ------------------------------------------------------------------ */ + +static int gntdev_open(struct inode *inode, struct file *flip) +{ + struct gntdev_priv *priv; + int ret = 0; + + priv = kzalloc(sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + INIT_LIST_HEAD(&priv->maps); + INIT_LIST_HEAD(&priv->freeable_maps); + mutex_init(&priv->lock); + + if (use_ptemod) { + priv->mm = get_task_mm(current); + if (!priv->mm) { + kfree(priv); + return -ENOMEM; + } + priv->mn.ops = &gntdev_mmu_ops; + ret = mmu_notifier_register(&priv->mn, priv->mm); + mmput(priv->mm); + } + + if (ret) { + kfree(priv); + return ret; + } + + flip->private_data = priv; + pr_debug("priv %p\n", priv); + + return 0; +} + +static int gntdev_release(struct inode *inode, struct file *flip) +{ + struct gntdev_priv *priv = flip->private_data; + struct grant_map *map; + + pr_debug("priv %p\n", priv); + + while (!list_empty(&priv->maps)) { + map = list_entry(priv->maps.next, struct grant_map, next); + list_del(&map->next); + gntdev_put_map(NULL /* already removed */, map); + } + WARN_ON(!list_empty(&priv->freeable_maps)); + + if (use_ptemod) + mmu_notifier_unregister(&priv->mn, priv->mm); + kfree(priv); + return 0; +} + +static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv, + struct ioctl_gntdev_map_grant_ref __user *u) +{ + struct ioctl_gntdev_map_grant_ref op; + struct grant_map *map; + int err; + + if (copy_from_user(&op, u, sizeof(op)) != 0) + return -EFAULT; + pr_debug("priv %p, add %d\n", priv, op.count); + if (unlikely(op.count <= 0)) + return -EINVAL; + + err = -ENOMEM; + map = gntdev_alloc_map(priv, op.count); + if (!map) + return err; + + if (unlikely(atomic_add_return(op.count, &pages_mapped) > limit)) { + pr_debug("can't map: over limit\n"); + gntdev_put_map(NULL, map); + return err; + } + + if (copy_from_user(map->grants, &u->refs, + sizeof(map->grants[0]) * op.count) != 0) { + gntdev_put_map(NULL, map); + return -EFAULT; + } + + mutex_lock(&priv->lock); + gntdev_add_map(priv, map); + op.index = map->index << PAGE_SHIFT; + mutex_unlock(&priv->lock); + + if (copy_to_user(u, &op, sizeof(op)) != 0) + return -EFAULT; + + return 0; +} + +static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv, + struct ioctl_gntdev_unmap_grant_ref __user *u) +{ + struct ioctl_gntdev_unmap_grant_ref op; + struct grant_map *map; + int err = -ENOENT; + + if (copy_from_user(&op, u, sizeof(op)) != 0) + return -EFAULT; + pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count); + + mutex_lock(&priv->lock); + map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count); + if (map) { + list_del(&map->next); + if (populate_freeable_maps) + list_add_tail(&map->next, &priv->freeable_maps); + err = 0; + } + mutex_unlock(&priv->lock); + if (map) + gntdev_put_map(priv, map); + return err; +} + +static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv, + struct ioctl_gntdev_get_offset_for_vaddr __user *u) +{ + struct ioctl_gntdev_get_offset_for_vaddr op; + struct vm_area_struct *vma; + struct grant_map *map; + int rv = -EINVAL; + + if (copy_from_user(&op, u, sizeof(op)) != 0) + return -EFAULT; + pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr); + + down_read(¤t->mm->mmap_sem); + vma = find_vma(current->mm, op.vaddr); + if (!vma || vma->vm_ops != &gntdev_vmops) + goto out_unlock; + + map = vma->vm_private_data; + if (!map) + goto out_unlock; + + op.offset = map->index << PAGE_SHIFT; + op.count = map->count; + rv = 0; + + out_unlock: + up_read(¤t->mm->mmap_sem); + + if (rv == 0 && copy_to_user(u, &op, sizeof(op)) != 0) + return -EFAULT; + return rv; +} + +static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u) +{ + struct ioctl_gntdev_unmap_notify op; + struct grant_map *map; + int rc; + int out_flags; + unsigned int out_event; + + if (copy_from_user(&op, u, sizeof(op))) + return -EFAULT; + + if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT)) + return -EINVAL; + + /* We need to grab a reference to the event channel we are going to use + * to send the notify before releasing the reference we may already have + * (if someone has called this ioctl twice). This is required so that + * it is possible to change the clear_byte part of the notification + * without disturbing the event channel part, which may now be the last + * reference to that event channel. + */ + if (op.action & UNMAP_NOTIFY_SEND_EVENT) { + if (evtchn_get(op.event_channel_port)) + return -EINVAL; + } + + out_flags = op.action; + out_event = op.event_channel_port; + + mutex_lock(&priv->lock); + + list_for_each_entry(map, &priv->maps, next) { + uint64_t begin = map->index << PAGE_SHIFT; + uint64_t end = (map->index + map->count) << PAGE_SHIFT; + if (op.index >= begin && op.index < end) + goto found; + } + rc = -ENOENT; + goto unlock_out; + + found: + if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) && + (map->flags & GNTMAP_readonly)) { + rc = -EINVAL; + goto unlock_out; + } + + out_flags = map->notify.flags; + out_event = map->notify.event; + + map->notify.flags = op.action; + map->notify.addr = op.index - (map->index << PAGE_SHIFT); + map->notify.event = op.event_channel_port; + + rc = 0; + + unlock_out: + mutex_unlock(&priv->lock); + + /* Drop the reference to the event channel we did not save in the map */ + if (out_flags & UNMAP_NOTIFY_SEND_EVENT) + evtchn_put(out_event); + + return rc; +} + +static long gntdev_ioctl(struct file *flip, + unsigned int cmd, unsigned long arg) +{ + struct gntdev_priv *priv = flip->private_data; + void __user *ptr = (void __user *)arg; + + switch (cmd) { + case IOCTL_GNTDEV_MAP_GRANT_REF: + return gntdev_ioctl_map_grant_ref(priv, ptr); + + case IOCTL_GNTDEV_UNMAP_GRANT_REF: + return gntdev_ioctl_unmap_grant_ref(priv, ptr); + + case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR: + return gntdev_ioctl_get_offset_for_vaddr(priv, ptr); + + case IOCTL_GNTDEV_SET_UNMAP_NOTIFY: + return gntdev_ioctl_notify(priv, ptr); + + default: + pr_debug("priv %p, unknown cmd %x\n", priv, cmd); + return -ENOIOCTLCMD; + } + + return 0; +} + +static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma) +{ + struct gntdev_priv *priv = flip->private_data; + int index = vma->vm_pgoff; + int count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; + struct grant_map *map; + int i, err = -EINVAL; + + if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED)) + return -EINVAL; + + pr_debug("map %d+%d at %lx (pgoff %lx)\n", + index, count, vma->vm_start, vma->vm_pgoff); + + mutex_lock(&priv->lock); + map = gntdev_find_map_index(priv, index, count); + if (!map) + goto unlock_out; + if (use_ptemod && map->vma) + goto unlock_out; + if (use_ptemod && priv->mm != vma->vm_mm) { + pr_warn("Huh? Other mm?\n"); + goto unlock_out; + } + + atomic_inc(&map->users); + + vma->vm_ops = &gntdev_vmops; + + vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP; + + if (use_ptemod) + vma->vm_flags |= VM_DONTCOPY; + + vma->vm_private_data = map; + + if (use_ptemod) + map->vma = vma; + + if (map->flags) { + if ((vma->vm_flags & VM_WRITE) && + (map->flags & GNTMAP_readonly)) + goto out_unlock_put; + } else { + map->flags = GNTMAP_host_map; + if (!(vma->vm_flags & VM_WRITE)) + map->flags |= GNTMAP_readonly; + } + + mutex_unlock(&priv->lock); + + if (use_ptemod) { + err = apply_to_page_range(vma->vm_mm, vma->vm_start, + vma->vm_end - vma->vm_start, + find_grant_ptes, map); + if (err) { + pr_warn("find_grant_ptes() failure.\n"); + goto out_put_map; + } + } + + err = map_grant_pages(map); + if (err) + goto out_put_map; + + if (!use_ptemod) { + for (i = 0; i < count; i++) { + err = vm_insert_page(vma, vma->vm_start + i*PAGE_SIZE, + map->pages[i]); + if (err) + goto out_put_map; + } + } else { +#ifdef CONFIG_X86 + /* + * If the PTEs were not made special by the grant map + * hypercall, do so here. + * + * This is racy since the mapping is already visible + * to userspace but userspace should be well-behaved + * enough to not touch it until the mmap() call + * returns. + */ + if (!xen_feature(XENFEAT_gnttab_map_avail_bits)) { + apply_to_page_range(vma->vm_mm, vma->vm_start, + vma->vm_end - vma->vm_start, + set_grant_ptes_as_special, NULL); + } +#endif + map->pages_vm_start = vma->vm_start; + } + + return 0; + +unlock_out: + mutex_unlock(&priv->lock); + return err; + +out_unlock_put: + mutex_unlock(&priv->lock); +out_put_map: + if (use_ptemod) + map->vma = NULL; + gntdev_put_map(priv, map); + return err; +} + +static const struct file_operations gntdev_fops = { + .owner = THIS_MODULE, + .open = gntdev_open, + .release = gntdev_release, + .mmap = gntdev_mmap, + .unlocked_ioctl = gntdev_ioctl +}; + +static struct miscdevice gntdev_miscdev = { + .minor = MISC_DYNAMIC_MINOR, + .name = "xen/gntdev", + .fops = &gntdev_fops, +}; + +/* ------------------------------------------------------------------ */ + +static int __init gntdev_init(void) +{ + int err; + + if (!xen_domain()) + return -ENODEV; + + use_ptemod = !xen_feature(XENFEAT_auto_translated_physmap); + + err = misc_register(&gntdev_miscdev); + if (err != 0) { + pr_err("Could not register gntdev device\n"); + return err; + } + return 0; +} + +static void __exit gntdev_exit(void) +{ + misc_deregister(&gntdev_miscdev); +} + +module_init(gntdev_init); +module_exit(gntdev_exit); + +/* ------------------------------------------------------------------ */ |