Merge branch 'stable/gntdev' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen
* 'stable/gntdev' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
xen/p2m: Fix module linking error.
xen p2m: clear the old pte when adding a page to m2p_override
xen gntdev: use gnttab_map_refs and gnttab_unmap_refs
xen: introduce gnttab_map_refs and gnttab_unmap_refs
xen p2m: transparently change the p2m mappings in the m2p override
xen/gntdev: Fix circular locking dependency
xen/gntdev: stop using "token" argument
xen: gntdev: move use of GNTMAP_contains_pte next to the map_op
xen: add m2p override mechanism
xen: move p2m handling to separate file
xen/gntdev: add VM_PFNMAP to vma
xen/gntdev: allow usermode to map granted pages
xen: define gnttab_set_map_op/unmap_op
Fix up trivial conflict in drivers/xen/Kconfig
diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 464d893..07bec09 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -71,7 +71,14 @@
but will have no xen contents.
config XEN_XENBUS_FRONTEND
- tristate
+ tristate
+
+config XEN_GNTDEV
+ tristate "userspace grant access device driver"
+ depends on XEN
+ select MMU_NOTIFIER
+ help
+ Allows userspace processes to use grants.
config XEN_PLATFORM_PCI
tristate "xen platform pci device driver"
diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index f81819b..5088cc2 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -9,6 +9,7 @@
obj-$(CONFIG_XEN_XENCOMM) += xencomm.o
obj-$(CONFIG_XEN_BALLOON) += balloon.o
obj-$(CONFIG_XEN_DEV_EVTCHN) += xen-evtchn.o
+obj-$(CONFIG_XEN_GNTDEV) += xen-gntdev.o
obj-$(CONFIG_XENFS) += xenfs/
obj-$(CONFIG_XEN_SYS_HYPERVISOR) += sys-hypervisor.o
obj-$(CONFIG_XEN_PLATFORM_PCI) += xen-platform-pci.o
@@ -16,5 +17,6 @@
obj-$(CONFIG_XEN_DOM0) += pci.o
xen-evtchn-y := evtchn.o
+xen-gntdev-y := gntdev.o
xen-platform-pci-y := platform-pci.o
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
new file mode 100644
index 0000000..1e31cdc
--- /dev/null
+++ b/drivers/xen/gntdev.c
@@ -0,0 +1,665 @@
+/******************************************************************************
+ * 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;
+ struct page **pages;
+};
+
+/* ------------------------------------------------------------------ */
+
+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;
+ int i;
+
+ 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);
+ add->pages = kzalloc(sizeof(add->pages[0]) * count, GFP_KERNEL);
+ if (NULL == add->grants ||
+ NULL == add->map_ops ||
+ NULL == add->unmap_ops ||
+ NULL == add->pages)
+ goto err;
+
+ for (i = 0; i < count; i++) {
+ add->pages[i] = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
+ if (add->pages[i] == NULL)
+ goto err;
+ }
+
+ add->index = 0;
+ add->count = count;
+ add->priv = priv;
+
+ if (add->count + priv->used > priv->limit)
+ goto err;
+
+ return add;
+
+err:
+ if (add->pages)
+ for (i = 0; i < count; i++) {
+ if (add->pages[i])
+ __free_page(add->pages[i]);
+ }
+ kfree(add->pages);
+ 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)
+{
+ int i;
+
+ if (!map)
+ return;
+
+ if (map->pages)
+ for (i = 0; i < map->count; i++) {
+ if (map->pages[i])
+ __free_page(map->pages[i]);
+ }
+ kfree(map->pages);
+ 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 = arbitrary_virt_to_machine(pte).maddr;
+
+ 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 = gnttab_map_refs(map->map_ops, map->pages, 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 = gnttab_unmap_refs(map->unmap_ops + offset, map->pages, 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;
+
+ spin_unlock(&priv->lock);
+
+ 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");
+ return err;
+ }
+
+ err = map_grant_pages(map);
+ if (err) {
+ printk(KERN_WARNING "map_grant_pages() failure.\n");
+ return err;
+ }
+
+ map->is_mapped = 1;
+
+ return 0;
+
+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);
+
+/* ------------------------------------------------------------------ */
diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 6c45318..9ef54eb 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -447,6 +447,52 @@
}
EXPORT_SYMBOL_GPL(gnttab_max_grant_frames);
+int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
+ struct page **pages, unsigned int count)
+{
+ int i, ret;
+ pte_t *pte;
+ unsigned long mfn;
+
+ ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map_ops, count);
+ if (ret)
+ return ret;
+
+ for (i = 0; i < count; i++) {
+ /* m2p override only supported for GNTMAP_contains_pte mappings */
+ if (!(map_ops[i].flags & GNTMAP_contains_pte))
+ continue;
+ pte = (pte_t *) (mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
+ (map_ops[i].host_addr & ~PAGE_MASK));
+ mfn = pte_mfn(*pte);
+ ret = m2p_add_override(mfn, pages[i]);
+ if (ret)
+ return ret;
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(gnttab_map_refs);
+
+int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
+ struct page **pages, unsigned int count)
+{
+ int i, ret;
+
+ ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops, count);
+ if (ret)
+ return ret;
+
+ for (i = 0; i < count; i++) {
+ ret = m2p_remove_override(pages[i]);
+ if (ret)
+ return ret;
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(gnttab_unmap_refs);
+
static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
{
struct gnttab_setup_table setup;