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alistair23-linux/drivers/xen/gntdev.c
David Vrabel a4cdb556ca xen/gntdev: add ioctl for grant copy 
Add IOCTL_GNTDEV_GRANT_COPY to allow applications to copy between user
space buffers and grant references.

This interface is similar to the GNTTABOP_copy hypercall ABI except
the local buffers are provided using a virtual address (instead of a
GFN and offset).  To avoid userspace from having to page align its
buffers the driver will use two or more ops if required.

If the ioctl returns 0, the application must check the status of each
segment with the segments status field.  If the ioctl returns a -ve
error code (EINVAL or EFAULT), the status of individual ops is
undefined.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2016-01-07 13:21:53 +00:00

1130 lines
27 KiB
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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
#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 <xen/page.h>
#include <asm/xen/hypervisor.h>
#include <asm/xen/hypercall.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 const 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 const 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);
mutex_lock(&priv->lock);
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));
mutex_unlock(&priv->lock);
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(&current->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(&current->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;
}
#define GNTDEV_COPY_BATCH 24
struct gntdev_copy_batch {
struct gnttab_copy ops[GNTDEV_COPY_BATCH];
struct page *pages[GNTDEV_COPY_BATCH];
s16 __user *status[GNTDEV_COPY_BATCH];
unsigned int nr_ops;
unsigned int nr_pages;
};
static int gntdev_get_page(struct gntdev_copy_batch *batch, void __user *virt,
bool writeable, unsigned long *gfn)
{
unsigned long addr = (unsigned long)virt;
struct page *page;
unsigned long xen_pfn;
int ret;
ret = get_user_pages_fast(addr, 1, writeable, &page);
if (ret < 0)
return ret;
batch->pages[batch->nr_pages++] = page;
xen_pfn = page_to_xen_pfn(page) + XEN_PFN_DOWN(addr & ~PAGE_MASK);
*gfn = pfn_to_gfn(xen_pfn);
return 0;
}
static void gntdev_put_pages(struct gntdev_copy_batch *batch)
{
unsigned int i;
for (i = 0; i < batch->nr_pages; i++)
put_page(batch->pages[i]);
batch->nr_pages = 0;
}
static int gntdev_copy(struct gntdev_copy_batch *batch)
{
unsigned int i;
gnttab_batch_copy(batch->ops, batch->nr_ops);
gntdev_put_pages(batch);
/*
* For each completed op, update the status if the op failed
* and all previous ops for the segment were successful.
*/
for (i = 0; i < batch->nr_ops; i++) {
s16 status = batch->ops[i].status;
s16 old_status;
if (status == GNTST_okay)
continue;
if (__get_user(old_status, batch->status[i]))
return -EFAULT;
if (old_status != GNTST_okay)
continue;
if (__put_user(status, batch->status[i]))
return -EFAULT;
}
batch->nr_ops = 0;
return 0;
}
static int gntdev_grant_copy_seg(struct gntdev_copy_batch *batch,
struct gntdev_grant_copy_segment *seg,
s16 __user *status)
{
uint16_t copied = 0;
/*
* Disallow local -> local copies since there is only space in
* batch->pages for one page per-op and this would be a very
* expensive memcpy().
*/
if (!(seg->flags & (GNTCOPY_source_gref | GNTCOPY_dest_gref)))
return -EINVAL;
/* Can't cross page if source/dest is a grant ref. */
if (seg->flags & GNTCOPY_source_gref) {
if (seg->source.foreign.offset + seg->len > XEN_PAGE_SIZE)
return -EINVAL;
}
if (seg->flags & GNTCOPY_dest_gref) {
if (seg->dest.foreign.offset + seg->len > XEN_PAGE_SIZE)
return -EINVAL;
}
if (put_user(GNTST_okay, status))
return -EFAULT;
while (copied < seg->len) {
struct gnttab_copy *op;
void __user *virt;
size_t len, off;
unsigned long gfn;
int ret;
if (batch->nr_ops >= GNTDEV_COPY_BATCH) {
ret = gntdev_copy(batch);
if (ret < 0)
return ret;
}
len = seg->len - copied;
op = &batch->ops[batch->nr_ops];
op->flags = 0;
if (seg->flags & GNTCOPY_source_gref) {
op->source.u.ref = seg->source.foreign.ref;
op->source.domid = seg->source.foreign.domid;
op->source.offset = seg->source.foreign.offset + copied;
op->flags |= GNTCOPY_source_gref;
} else {
virt = seg->source.virt + copied;
off = (unsigned long)virt & ~XEN_PAGE_MASK;
len = min(len, (size_t)XEN_PAGE_SIZE - off);
ret = gntdev_get_page(batch, virt, false, &gfn);
if (ret < 0)
return ret;
op->source.u.gmfn = gfn;
op->source.domid = DOMID_SELF;
op->source.offset = off;
}
if (seg->flags & GNTCOPY_dest_gref) {
op->dest.u.ref = seg->dest.foreign.ref;
op->dest.domid = seg->dest.foreign.domid;
op->dest.offset = seg->dest.foreign.offset + copied;
op->flags |= GNTCOPY_dest_gref;
} else {
virt = seg->dest.virt + copied;
off = (unsigned long)virt & ~XEN_PAGE_MASK;
len = min(len, (size_t)XEN_PAGE_SIZE - off);
ret = gntdev_get_page(batch, virt, true, &gfn);
if (ret < 0)
return ret;
op->dest.u.gmfn = gfn;
op->dest.domid = DOMID_SELF;
op->dest.offset = off;
}
op->len = len;
copied += len;
batch->status[batch->nr_ops] = status;
batch->nr_ops++;
}
return 0;
}
static long gntdev_ioctl_grant_copy(struct gntdev_priv *priv, void __user *u)
{
struct ioctl_gntdev_grant_copy copy;
struct gntdev_copy_batch batch;
unsigned int i;
int ret = 0;
if (copy_from_user(&copy, u, sizeof(copy)))
return -EFAULT;
batch.nr_ops = 0;
batch.nr_pages = 0;
for (i = 0; i < copy.count; i++) {
struct gntdev_grant_copy_segment seg;
if (copy_from_user(&seg, &copy.segments[i], sizeof(seg))) {
ret = -EFAULT;
goto out;
}
ret = gntdev_grant_copy_seg(&batch, &seg, &copy.segments[i].status);
if (ret < 0)
goto out;
cond_resched();
}
if (batch.nr_ops)
ret = gntdev_copy(&batch);
return ret;
out:
gntdev_put_pages(&batch);
return ret;
}
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);
case IOCTL_GNTDEV_GRANT_COPY:
return gntdev_ioctl_grant_copy(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 | VM_IO;
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);
/* ------------------------------------------------------------------ */
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