/****************************************************************************** * 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 #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 */ spinlock_t 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 page **pages; }; 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) free_xenballooned_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); } 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->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->pages) goto err; if (alloc_xenballooned_pages(count, add->pages, false /* lowmem */)) 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->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) { spin_lock(&priv->lock); list_del(&map->next); spin_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; 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; } 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 level; unsigned long address = (unsigned long) pfn_to_kaddr(page_to_pfn(map->pages[i])); pte_t *ptep; u64 pte_maddr = 0; BUG_ON(PageHighMem(map->pages[i])); ptep = lookup_address(address, &level); pte_maddr = arbitrary_virt_to_machine(ptep).maddr; gnttab_set_map_op(&map->kmap_ops[i], pte_maddr, map->flags | GNTMAP_host_map | GNTMAP_contains_pte, map->grants[i].ref, map->grants[i].domid); } } 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; else { BUG_ON(map->map_ops[i].handle == -1); map->unmap_ops[i].handle = map->map_ops[i].handle; pr_debug("map handle=%d\n", map->map_ops[i].handle); } } return err; } static int __unmap_grant_pages(struct grant_map *map, int offset, int pages) { int i, err = 0; 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; } } err = gnttab_unmap_refs(map->unmap_ops + offset, use_ptemod ? map->kmap_ops + offset : NULL, map->pages + offset, pages); 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. */ spin_lock(&priv->lock); map->vma = NULL; spin_unlock(&priv->lock); } vma->vm_private_data = NULL; gntdev_put_map(priv, map); } static struct vm_operations_struct gntdev_vmops = { .open = gntdev_vma_open, .close = gntdev_vma_close, }; /* ------------------------------------------------------------------ */ 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; spin_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); } spin_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; spin_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); } spin_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); spin_lock_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; } spin_lock(&priv->lock); gntdev_add_map(priv, map); op.index = map->index << PAGE_SHIFT; spin_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); spin_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; } spin_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; spin_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: spin_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); spin_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) { printk(KERN_WARNING "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; } spin_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) { printk(KERN_WARNING "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; } } return 0; unlock_out: spin_unlock(&priv->lock); return err; out_unlock_put: spin_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_pv_domain(); err = misc_register(&gntdev_miscdev); if (err != 0) { printk(KERN_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); /* ------------------------------------------------------------------ */