linux/drivers/xen/gntdev.c

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/******************************************************************************
* 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,
GNTMAP_contains_pte | map->flags,
map->grants[pgnr].ref,
map->grants[pgnr].domid);
gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr,
GNTMAP_contains_pte | 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|VM_PFNMAP;
vma->vm_private_data = map;
map->vma = vma;
map->flags = GNTMAP_host_map | GNTMAP_application_map;
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);
/* ------------------------------------------------------------------ */