xen/gntalloc,gntdev: Add unmap notify ioctl
This ioctl allows the users of a shared page to be notified when the other end exits abnormally. [v2: updated description in structs] Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Daniel De Graaf
Konrad Rzeszutek Wilk
Родитель
dd3140588d
Коммит
bdc612dc69
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@ -60,11 +60,13 @@
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#include <linux/uaccess.h>
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#include <linux/types.h>
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#include <linux/list.h>
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#include <linux/highmem.h>
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#include <xen/xen.h>
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#include <xen/page.h>
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#include <xen/grant_table.h>
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#include <xen/gntalloc.h>
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#include <xen/events.h>
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static int limit = 1024;
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module_param(limit, int, 0644);
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@ -75,6 +77,12 @@ static LIST_HEAD(gref_list);
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static DEFINE_SPINLOCK(gref_lock);
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static int gref_size;
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struct notify_info {
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uint16_t pgoff:12; /* Bits 0-11: Offset of the byte to clear */
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uint16_t flags:2; /* Bits 12-13: Unmap notification flags */
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int event; /* Port (event channel) to notify */
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};
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/* Metadata on a grant reference. */
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struct gntalloc_gref {
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struct list_head next_gref; /* list entry gref_list */
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@ -83,6 +91,7 @@ struct gntalloc_gref {
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uint64_t file_index; /* File offset for mmap() */
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unsigned int users; /* Use count - when zero, waiting on Xen */
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grant_ref_t gref_id; /* The grant reference number */
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struct notify_info notify; /* Unmap notification */
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};
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struct gntalloc_file_private_data {
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@ -164,6 +173,16 @@ undo:
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static void __del_gref(struct gntalloc_gref *gref)
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{
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if (gref->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
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uint8_t *tmp = kmap(gref->page);
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tmp[gref->notify.pgoff] = 0;
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kunmap(gref->page);
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}
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if (gref->notify.flags & UNMAP_NOTIFY_SEND_EVENT)
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notify_remote_via_evtchn(gref->notify.event);
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gref->notify.flags = 0;
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if (gref->gref_id > 0) {
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if (gnttab_query_foreign_access(gref->gref_id))
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return;
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@ -349,6 +368,43 @@ dealloc_grant_out:
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return rc;
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}
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static long gntalloc_ioctl_unmap_notify(struct gntalloc_file_private_data *priv,
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void __user *arg)
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{
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struct ioctl_gntalloc_unmap_notify op;
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struct gntalloc_gref *gref;
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uint64_t index;
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int pgoff;
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int rc;
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if (copy_from_user(&op, arg, sizeof(op)))
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return -EFAULT;
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index = op.index & ~(PAGE_SIZE - 1);
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pgoff = op.index & (PAGE_SIZE - 1);
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spin_lock(&gref_lock);
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gref = find_grefs(priv, index, 1);
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if (!gref) {
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rc = -ENOENT;
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goto unlock_out;
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}
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if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT)) {
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rc = -EINVAL;
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goto unlock_out;
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}
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gref->notify.flags = op.action;
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gref->notify.pgoff = pgoff;
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gref->notify.event = op.event_channel_port;
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rc = 0;
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unlock_out:
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spin_unlock(&gref_lock);
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return rc;
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}
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static long gntalloc_ioctl(struct file *filp, unsigned int cmd,
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unsigned long arg)
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{
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@ -361,6 +417,9 @@ static long gntalloc_ioctl(struct file *filp, unsigned int cmd,
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case IOCTL_GNTALLOC_DEALLOC_GREF:
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return gntalloc_ioctl_dealloc(priv, (void __user *)arg);
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case IOCTL_GNTALLOC_SET_UNMAP_NOTIFY:
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return gntalloc_ioctl_unmap_notify(priv, (void __user *)arg);
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default:
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return -ENOIOCTLCMD;
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}
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@ -37,6 +37,7 @@
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#include <xen/xen.h>
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#include <xen/grant_table.h>
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#include <xen/gntdev.h>
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#include <xen/events.h>
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#include <asm/xen/hypervisor.h>
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#include <asm/xen/hypercall.h>
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#include <asm/xen/page.h>
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@ -63,6 +64,13 @@ struct gntdev_priv {
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struct mmu_notifier mn;
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};
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struct unmap_notify {
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int flags;
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/* Address relative to the start of the grant_map */
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int addr;
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int event;
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};
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struct grant_map {
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struct list_head next;
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struct vm_area_struct *vma;
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@ -71,6 +79,7 @@ struct grant_map {
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int flags;
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int is_mapped;
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atomic_t users;
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struct unmap_notify notify;
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struct ioctl_gntdev_grant_ref *grants;
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struct gnttab_map_grant_ref *map_ops;
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struct gnttab_unmap_grant_ref *unmap_ops;
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@ -165,7 +174,7 @@ static struct grant_map *gntdev_find_map_index(struct gntdev_priv *priv,
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list_for_each_entry(map, &priv->maps, next) {
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if (map->index != index)
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continue;
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if (map->count != count)
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if (count && map->count != count)
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continue;
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return map;
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}
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@ -184,6 +193,10 @@ static void gntdev_put_map(struct grant_map *map)
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atomic_sub(map->count, &pages_mapped);
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if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) {
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notify_remote_via_evtchn(map->notify.event);
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}
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if (map->pages) {
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if (!use_ptemod)
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unmap_grant_pages(map, 0, map->count);
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@ -274,6 +287,16 @@ static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
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{
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int i, err = 0;
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if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
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int pgno = (map->notify.addr >> PAGE_SHIFT);
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if (pgno >= offset && pgno < offset + pages) {
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uint8_t *tmp = kmap(map->pages[pgno]);
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tmp[map->notify.addr & (PAGE_SIZE-1)] = 0;
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kunmap(map->pages[pgno]);
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map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
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}
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}
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pr_debug("map %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
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err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages, pages);
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if (err)
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@ -519,6 +542,39 @@ static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
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return 0;
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}
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static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
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{
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struct ioctl_gntdev_unmap_notify op;
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struct grant_map *map;
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int rc;
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if (copy_from_user(&op, u, sizeof(op)))
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return -EFAULT;
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if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT))
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return -EINVAL;
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spin_lock(&priv->lock);
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list_for_each_entry(map, &priv->maps, next) {
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uint64_t begin = map->index << PAGE_SHIFT;
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uint64_t end = (map->index + map->count) << PAGE_SHIFT;
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if (op.index >= begin && op.index < end)
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goto found;
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}
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rc = -ENOENT;
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goto unlock_out;
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found:
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map->notify.flags = op.action;
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map->notify.addr = op.index - (map->index << PAGE_SHIFT);
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map->notify.event = op.event_channel_port;
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rc = 0;
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unlock_out:
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spin_unlock(&priv->lock);
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return rc;
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}
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static long gntdev_ioctl(struct file *flip,
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unsigned int cmd, unsigned long arg)
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{
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@ -535,6 +591,9 @@ static long gntdev_ioctl(struct file *flip,
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case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
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return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
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case IOCTL_GNTDEV_SET_UNMAP_NOTIFY:
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return gntdev_ioctl_notify(priv, ptr);
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default:
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pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
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return -ENOIOCTLCMD;
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@ -47,4 +47,36 @@ struct ioctl_gntalloc_dealloc_gref {
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/* Number of references to unmap */
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uint32_t count;
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};
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/*
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* Sets up an unmap notification within the page, so that the other side can do
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* cleanup if this side crashes. Required to implement cross-domain robust
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* mutexes or close notification on communication channels.
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*
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* Each mapped page only supports one notification; multiple calls referring to
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* the same page overwrite the previous notification. You must clear the
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* notification prior to the IOCTL_GNTALLOC_DEALLOC_GREF if you do not want it
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* to occur.
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*/
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#define IOCTL_GNTALLOC_SET_UNMAP_NOTIFY \
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_IOC(_IOC_NONE, 'G', 7, sizeof(struct ioctl_gntalloc_unmap_notify))
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struct ioctl_gntalloc_unmap_notify {
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/* IN parameters */
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/* Offset in the file descriptor for a byte within the page (same as
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* used in mmap). If using UNMAP_NOTIFY_CLEAR_BYTE, this is the byte to
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* be cleared. Otherwise, it can be any byte in the page whose
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* notification we are adjusting.
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*/
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uint64_t index;
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/* Action(s) to take on unmap */
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uint32_t action;
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/* Event channel to notify */
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uint32_t event_channel_port;
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};
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/* Clear (set to zero) the byte specified by index */
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#define UNMAP_NOTIFY_CLEAR_BYTE 0x1
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/* Send an interrupt on the indicated event channel */
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#define UNMAP_NOTIFY_SEND_EVENT 0x2
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#endif /* __LINUX_PUBLIC_GNTALLOC_H__ */
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@ -116,4 +116,35 @@ struct ioctl_gntdev_set_max_grants {
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uint32_t count;
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};
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/*
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* Sets up an unmap notification within the page, so that the other side can do
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* cleanup if this side crashes. Required to implement cross-domain robust
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* mutexes or close notification on communication channels.
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*
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* Each mapped page only supports one notification; multiple calls referring to
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* the same page overwrite the previous notification. You must clear the
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* notification prior to the IOCTL_GNTALLOC_DEALLOC_GREF if you do not want it
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* to occur.
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*/
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#define IOCTL_GNTDEV_SET_UNMAP_NOTIFY \
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_IOC(_IOC_NONE, 'G', 7, sizeof(struct ioctl_gntdev_unmap_notify))
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struct ioctl_gntdev_unmap_notify {
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/* IN parameters */
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/* Offset in the file descriptor for a byte within the page (same as
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* used in mmap). If using UNMAP_NOTIFY_CLEAR_BYTE, this is the byte to
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* be cleared. Otherwise, it can be any byte in the page whose
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* notification we are adjusting.
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*/
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uint64_t index;
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/* Action(s) to take on unmap */
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uint32_t action;
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/* Event channel to notify */
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uint32_t event_channel_port;
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};
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/* Clear (set to zero) the byte specified by index */
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#define UNMAP_NOTIFY_CLEAR_BYTE 0x1
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/* Send an interrupt on the indicated event channel */
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#define UNMAP_NOTIFY_SEND_EVENT 0x2
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#endif /* __LINUX_PUBLIC_GNTDEV_H__ */
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