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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>
* (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
*
* 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/uaccess.h>
#include <linux/sched.h>
#include <linux/sched/mm.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/highmem.h>
#include <linux/refcount.h>
#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
#include <linux/of_device.h>
#endif
#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>
#include "gntdev-common.h"
#ifdef CONFIG_XEN_GNTDEV_DMABUF
#include "gntdev-dmabuf.h"
#endif
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
static int unmap_grant_pages(struct gntdev_grant_map *map,
int offset, int pages);
static struct miscdevice gntdev_miscdev;
/* ------------------------------------------------------------------ */
bool gntdev_account_mapped_pages(int count)
{
return atomic_add_return(count, &pages_mapped) > limit;
}
static void gntdev_print_maps(struct gntdev_priv *priv,
char *text, int text_index)
{
#ifdef DEBUG
struct gntdev_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 gntdev_grant_map *map)
{
if (map == NULL)
return;
#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
if (map->dma_vaddr) {
struct gnttab_dma_alloc_args args;
args.dev = map->dma_dev;
args.coherent = !!(map->dma_flags & GNTDEV_DMA_FLAG_COHERENT);
args.nr_pages = map->count;
args.pages = map->pages;
args.frames = map->frames;
args.vaddr = map->dma_vaddr;
args.dev_bus_addr = map->dma_bus_addr;
gnttab_dma_free_pages(&args);
} else
#endif
if (map->pages)
gnttab_free_pages(map->count, map->pages);
#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
kfree(map->frames);
#endif
kfree(map->pages);
kfree(map->grants);
kfree(map->map_ops);
kfree(map->unmap_ops);
kfree(map->kmap_ops);
kfree(map->kunmap_ops);
kfree(map);
}
struct gntdev_grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count,
int dma_flags)
{
struct gntdev_grant_map *add;
int i;
add = kzalloc(sizeof(*add), 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;
#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
add->dma_flags = dma_flags;
/*
* Check if this mapping is requested to be backed
* by a DMA buffer.
*/
if (dma_flags & (GNTDEV_DMA_FLAG_WC | GNTDEV_DMA_FLAG_COHERENT)) {
struct gnttab_dma_alloc_args args;
add->frames = kcalloc(count, sizeof(add->frames[0]),
GFP_KERNEL);
if (!add->frames)
goto err;
/* Remember the device, so we can free DMA memory. */
add->dma_dev = priv->dma_dev;
args.dev = priv->dma_dev;
args.coherent = !!(dma_flags & GNTDEV_DMA_FLAG_COHERENT);
args.nr_pages = count;
args.pages = add->pages;
args.frames = add->frames;
if (gnttab_dma_alloc_pages(&args))
goto err;
add->dma_vaddr = args.vaddr;
add->dma_bus_addr = args.dev_bus_addr;
} else
#endif
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;
refcount_set(&add->users, 1);
return add;
err:
gntdev_free_map(add);
return NULL;
}
void gntdev_add_map(struct gntdev_priv *priv, struct gntdev_grant_map *add)
{
struct gntdev_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 gntdev_grant_map *gntdev_find_map_index(struct gntdev_priv *priv,
int index, int count)
{
struct gntdev_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;
}
void gntdev_put_map(struct gntdev_priv *priv, struct gntdev_grant_map *map)
{
if (!map)
return;
if (!refcount_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 gntdev_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
int gntdev_map_grant_pages(struct gntdev_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;
#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
else if (map->dma_vaddr) {
unsigned long bfn;
bfn = pfn_to_bfn(page_to_pfn(map->pages[i]));
map->unmap_ops[i].dev_bus_addr = __pfn_to_phys(bfn);
}
#endif
}
return err;
}
static int __unmap_grant_pages(struct gntdev_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 gntdev_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)
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 gntdev_grant_map *map = vma->vm_private_data;
pr_debug("gntdev_vma_open %p\n", vma);
refcount_inc(&map->users);
}
static void gntdev_vma_close(struct vm_area_struct *vma)
{
struct gntdev_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 gntdev_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 bool in_range(struct gntdev_grant_map *map,
unsigned long start, unsigned long end)
{
if (!map->vma)
return false;
if (map->vma->vm_start >= end)
return false;
if (map->vma->vm_end <= start)
return false;
return true;
}
static int unmap_if_in_range(struct gntdev_grant_map *map,
unsigned long start, unsigned long end,
bool blockable)
{
unsigned long mstart, mend;
int err;
if (!in_range(map, start, end))
return 0;
if (!blockable)
return -EAGAIN;
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);
return 0;
}
static int mn_invl_range_start(struct mmu_notifier *mn,
const struct mmu_notifier_range *range)
{
struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
struct gntdev_grant_map *map;
int ret = 0;
if (range->blockable)
mutex_lock(&priv->lock);
else if (!mutex_trylock(&priv->lock))
return -EAGAIN;
list_for_each_entry(map, &priv->maps, next) {
ret = unmap_if_in_range(map, range->start, range->end,
range->blockable);
if (ret)
goto out_unlock;
}
list_for_each_entry(map, &priv->freeable_maps, next) {
ret = unmap_if_in_range(map, range->start, range->end,
range->blockable);
if (ret)
goto out_unlock;
}
out_unlock:
mutex_unlock(&priv->lock);
return ret;
}
static void mn_release(struct mmu_notifier *mn,
struct mm_struct *mm)
{
struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
struct gntdev_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_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);
#ifdef CONFIG_XEN_GNTDEV_DMABUF
priv->dmabuf_priv = gntdev_dmabuf_init();
if (IS_ERR(priv->dmabuf_priv)) {
ret = PTR_ERR(priv->dmabuf_priv);
kfree(priv);
return ret;
}
#endif
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;
#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
priv->dma_dev = gntdev_miscdev.this_device;
/*
* The device is not spawn from a device tree, so arch_setup_dma_ops
* is not called, thus leaving the device with dummy DMA ops.
* Fix this by calling of_dma_configure() with a NULL node to set
* default DMA ops.
*/
of_dma_configure(priv->dma_dev, NULL, true);
#endif
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 gntdev_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 gntdev_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);
#ifdef CONFIG_XEN_GNTDEV_DMABUF
gntdev_dmabuf_fini(priv->dmabuf_priv);
#endif
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 gntdev_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, 0 /* This is not a dma-buf. */);
if (!map)
return err;
if (unlikely(gntdev_account_mapped_pages(op.count))) {
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 gntdev_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 gntdev_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 gntdev_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 16
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);
#ifdef CONFIG_XEN_GNTDEV_DMABUF
case IOCTL_GNTDEV_DMABUF_EXP_FROM_REFS:
return gntdev_ioctl_dmabuf_exp_from_refs(priv, use_ptemod, ptr);
case IOCTL_GNTDEV_DMABUF_EXP_WAIT_RELEASED:
return gntdev_ioctl_dmabuf_exp_wait_released(priv, ptr);
case IOCTL_GNTDEV_DMABUF_IMP_TO_REFS:
return gntdev_ioctl_dmabuf_imp_to_refs(priv, ptr);
case IOCTL_GNTDEV_DMABUF_IMP_RELEASE:
return gntdev_ioctl_dmabuf_imp_release(priv, ptr);
#endif
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_pages(vma);
struct gntdev_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;
}
refcount_inc(&map->users);
vma->vm_ops = &gntdev_vmops;
vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP | VM_MIXEDMAP;
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) {
map->pages_vm_start = vma->vm_start;
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 = gntdev_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
}
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;
unmap_grant_pages(map, 0, map->count);
}
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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