diff options
Diffstat (limited to 'drivers/xen/gntdev.c')
| -rw-r--r-- | drivers/xen/gntdev.c | 635 |
1 files changed, 635 insertions, 0 deletions
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c new file mode 100644 index 000000000000..cfe063372aa4 --- /dev/null +++ b/drivers/xen/gntdev.c @@ -0,0 +1,635 @@ +/****************************************************************************** + * 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 <xen/xen.h> +#include <xen/grant_table.h> +#include <xen/gntdev.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; +module_param(limit, int, 0644); +MODULE_PARM_DESC(limit, "Maximum number of grants that may be mapped at " + "once by a gntdev instance"); + +struct gntdev_priv { + struct list_head maps; + uint32_t used; + uint32_t limit; + /* lock protects maps from concurrent changes */ + spinlock_t lock; + struct mm_struct *mm; + struct mmu_notifier mn; +}; + +struct grant_map { + struct list_head next; + struct gntdev_priv *priv; + struct vm_area_struct *vma; + int index; + int count; + int flags; + int is_mapped; + struct ioctl_gntdev_grant_ref *grants; + struct gnttab_map_grant_ref *map_ops; + struct gnttab_unmap_grant_ref *unmap_ops; +}; + +/* ------------------------------------------------------------------ */ + +static void gntdev_print_maps(struct gntdev_priv *priv, + char *text, int text_index) +{ +#ifdef DEBUG + struct grant_map *map; + + pr_debug("maps list (priv %p, usage %d/%d)\n", + priv, priv->used, priv->limit); + + 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 struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count) +{ + struct grant_map *add; + + add = kzalloc(sizeof(struct grant_map), GFP_KERNEL); + if (NULL == add) + return NULL; + + add->grants = kzalloc(sizeof(add->grants[0]) * count, GFP_KERNEL); + add->map_ops = kzalloc(sizeof(add->map_ops[0]) * count, GFP_KERNEL); + add->unmap_ops = kzalloc(sizeof(add->unmap_ops[0]) * count, GFP_KERNEL); + if (NULL == add->grants || + NULL == add->map_ops || + NULL == add->unmap_ops) + goto err; + + add->index = 0; + add->count = count; + add->priv = priv; + + if (add->count + priv->used > priv->limit) + goto err; + + return add; + +err: + kfree(add->grants); + kfree(add->map_ops); + kfree(add->unmap_ops); + kfree(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: + priv->used += add->count; + 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 (map->count != count) + continue; + return map; + } + return NULL; +} + +static struct grant_map *gntdev_find_map_vaddr(struct gntdev_priv *priv, + unsigned long vaddr) +{ + struct grant_map *map; + + list_for_each_entry(map, &priv->maps, next) { + if (!map->vma) + continue; + if (vaddr < map->vma->vm_start) + continue; + if (vaddr >= map->vma->vm_end) + continue; + return map; + } + return NULL; +} + +static int gntdev_del_map(struct grant_map *map) +{ + int i; + + if (map->vma) + return -EBUSY; + for (i = 0; i < map->count; i++) + if (map->unmap_ops[i].handle) + return -EBUSY; + + map->priv->used -= map->count; + list_del(&map->next); + return 0; +} + +static void gntdev_free_map(struct grant_map *map) +{ + if (!map) + return; + kfree(map->grants); + kfree(map->map_ops); + kfree(map->unmap_ops); + kfree(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; + u64 pte_maddr; + + BUG_ON(pgnr >= map->count); + pte_maddr = (u64)pfn_to_mfn(page_to_pfn(token)) << PAGE_SHIFT; + pte_maddr += (unsigned long)pte & ~PAGE_MASK; + gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, map->flags, + map->grants[pgnr].ref, + map->grants[pgnr].domid); + gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, map->flags, + 0 /* handle */); + return 0; +} + +static int map_grant_pages(struct grant_map *map) +{ + int i, err = 0; + + pr_debug("map %d+%d\n", map->index, map->count); + err = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, + map->map_ops, map->count); + if (err) + return err; + + for (i = 0; i < map->count; i++) { + if (map->map_ops[i].status) + err = -EINVAL; + map->unmap_ops[i].handle = map->map_ops[i].handle; + } + return err; +} + +static int unmap_grant_pages(struct grant_map *map, int offset, int pages) +{ + int i, err = 0; + + pr_debug("map %d+%d [%d+%d]\n", map->index, map->count, offset, pages); + err = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, + map->unmap_ops + offset, pages); + if (err) + return err; + + for (i = 0; i < pages; i++) { + if (map->unmap_ops[offset+i].status) + err = -EINVAL; + map->unmap_ops[offset+i].handle = 0; + } + return err; +} + +/* ------------------------------------------------------------------ */ + +static void gntdev_vma_close(struct vm_area_struct *vma) +{ + struct grant_map *map = vma->vm_private_data; + + pr_debug("close %p\n", vma); + map->is_mapped = 0; + map->vma = NULL; + vma->vm_private_data = NULL; +} + +static int gntdev_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf) +{ + pr_debug("vaddr %p, pgoff %ld (shouldn't happen)\n", + vmf->virtual_address, vmf->pgoff); + vmf->flags = VM_FAULT_ERROR; + return 0; +} + +static struct vm_operations_struct gntdev_vmops = { + .close = gntdev_vma_close, + .fault = gntdev_vma_fault, +}; + +/* ------------------------------------------------------------------ */ + +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; + unsigned long mstart, mend; + int err; + + spin_lock(&priv->lock); + list_for_each_entry(map, &priv->maps, next) { + if (!map->vma) + continue; + if (!map->is_mapped) + continue; + if (map->vma->vm_start >= end) + continue; + if (map->vma->vm_end <= start) + continue; + 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); + } + 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); + } + spin_unlock(&priv->lock); +} + +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); + spin_lock_init(&priv->lock); + priv->limit = limit; + + 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; + int err; + + pr_debug("priv %p\n", priv); + + spin_lock(&priv->lock); + while (!list_empty(&priv->maps)) { + map = list_entry(priv->maps.next, struct grant_map, next); + err = gntdev_del_map(map); + if (WARN_ON(err)) + gntdev_free_map(map); + + } + spin_unlock(&priv->lock); + + 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; + if (unlikely(op.count > priv->limit)) + return -EINVAL; + + err = -ENOMEM; + map = gntdev_alloc_map(priv, op.count); + if (!map) + return err; + if (copy_from_user(map->grants, &u->refs, + sizeof(map->grants[0]) * op.count) != 0) { + gntdev_free_map(map); + return err; + } + + 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) { + spin_lock(&priv->lock); + gntdev_del_map(map); + spin_unlock(&priv->lock); + gntdev_free_map(map); + return err; + } + 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) + err = gntdev_del_map(map); + spin_unlock(&priv->lock); + if (!err) + gntdev_free_map(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 grant_map *map; + + 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); + + spin_lock(&priv->lock); + map = gntdev_find_map_vaddr(priv, op.vaddr); + if (map == NULL || + map->vma->vm_start != op.vaddr) { + spin_unlock(&priv->lock); + return -EINVAL; + } + op.offset = map->index << PAGE_SHIFT; + op.count = map->count; + spin_unlock(&priv->lock); + + if (copy_to_user(u, &op, sizeof(op)) != 0) + return -EFAULT; + return 0; +} + +static long gntdev_ioctl_set_max_grants(struct gntdev_priv *priv, + struct ioctl_gntdev_set_max_grants __user *u) +{ + struct ioctl_gntdev_set_max_grants op; + + if (copy_from_user(&op, u, sizeof(op)) != 0) + return -EFAULT; + pr_debug("priv %p, limit %d\n", priv, op.count); + if (op.count > limit) + return -E2BIG; + + spin_lock(&priv->lock); + priv->limit = op.count; + spin_unlock(&priv->lock); + return 0; +} + +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_MAX_GRANTS: + return gntdev_ioctl_set_max_grants(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 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 (map->vma) + goto unlock_out; + if (priv->mm != vma->vm_mm) { + printk(KERN_WARNING "Huh? Other mm?\n"); + goto unlock_out; + } + + vma->vm_ops = &gntdev_vmops; + + vma->vm_flags |= VM_RESERVED|VM_DONTCOPY|VM_DONTEXPAND; + + vma->vm_private_data = map; + map->vma = vma; + + map->flags = GNTMAP_host_map | GNTMAP_application_map | GNTMAP_contains_pte; + if (!(vma->vm_flags & VM_WRITE)) + map->flags |= GNTMAP_readonly; + + 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 unlock_out; + } + + err = map_grant_pages(map); + if (err) { + printk(KERN_WARNING "map_grant_pages() failure.\n"); + goto unlock_out; + } + map->is_mapped = 1; + +unlock_out: + spin_unlock(&priv->lock); + 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; + + 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); + +/* ------------------------------------------------------------------ */ |