/****************************************************************************** * gntalloc.c * * Device for creating grant references (in user-space) that may be shared * with other domains. * * 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 */ /* * This driver exists to allow userspace programs in Linux to allocate kernel * memory that will later be shared with another domain. Without this device, * Linux userspace programs cannot create grant references. * * How this stuff works: * X -> granting a page to Y * Y -> mapping the grant from X * * 1. X uses the gntalloc device to allocate a page of kernel memory, P. * 2. X creates an entry in the grant table that says domid(Y) can access P. * This is done without a hypercall unless the grant table needs expansion. * 3. X gives the grant reference identifier, GREF, to Y. * 4. Y maps the page, either directly into kernel memory for use in a backend * driver, or via a the gntdev device to map into the address space of an * application running in Y. This is the first point at which Xen does any * tracking of the page. * 5. A program in X mmap()s a segment of the gntalloc device that corresponds * to the shared page, and can now communicate with Y over the shared page. * * * NOTE TO USERSPACE LIBRARIES: * The grant allocation and mmap()ing are, naturally, two separate operations. * You set up the sharing by calling the create ioctl() and then the mmap(). * Teardown requires munmap() and either close() or ioctl(). * * WARNING: Since Xen does not allow a guest to forcibly end the use of a grant * reference, this device can be used to consume kernel memory by leaving grant * references mapped by another domain when an application exits. Therefore, * there is a global limit on the number of pages that can be allocated. When * all references to the page are unmapped, it will be freed during the next * grant operation. */ #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt #include <linux/atomic.h>#include <linux/module.h>#include <linux/miscdevice.h>#include <linux/kernel.h>#include <linux/init.h>#include <linux/slab.h>#include <linux/fs.h>#include <linux/device.h>#include <linux/mm.h>#include <linux/uaccess.h>#include <linux/types.h>#include <linux/list.h>#include <linux/highmem.h> #include <xen/xen.h>#include <xen/page.h>#include <xen/grant_table.h>#include <xen/gntalloc.h>#include <xen/events.h> static unsigned int limit = 1024;module_param(limit, uint, 0644);MODULE_PARM_DESC(limit, "Maximum number of grants that may be allocated by " "the gntalloc device"); static LIST_HEAD(gref_list);static DEFINE_MUTEX(gref_mutex);static unsigned int gref_size; struct notify_info { uint16_t pgoff:12; /* Bits 0-11: Offset of the byte to clear */ uint16_t flags:2; /* Bits 12-13: Unmap notification flags */ int event; /* Port (event channel) to notify */}; /* Metadata on a grant reference. */struct gntalloc_gref { struct list_head next_gref; /* list entry gref_list */ struct list_head next_file; /* list entry file->list, if open */ struct page *page; /* The shared page */ uint64_t file_index; /* File offset for mmap() */ unsigned int users; /* Use count - when zero, waiting on Xen */ grant_ref_t gref_id; /* The grant reference number */ struct notify_info notify; /* Unmap notification */}; struct gntalloc_file_private_data { struct list_head list; uint64_t index;}; struct gntalloc_vma_private_data { struct gntalloc_gref *gref; int users; int count;}; static void __del_gref(struct gntalloc_gref *gref); static void do_cleanup(void){ struct gntalloc_gref *gref, *n; list_for_each_entry_safe(gref, n, &gref_list, next_gref) { if (!gref->users) __del_gref(gref); }} static int add_grefs(struct ioctl_gntalloc_alloc_gref *op, uint32_t *gref_ids, struct gntalloc_file_private_data *priv){ int i, rc, readonly; LIST_HEAD(queue_gref); LIST_HEAD(queue_file); struct gntalloc_gref *gref, *next; readonly = !(op->flags & GNTALLOC_FLAG_WRITABLE); for (i = 0; i < op->count; i++) { gref = kzalloc_obj(*gref); if (!gref) { rc = -ENOMEM; goto undo; } list_add_tail(&gref->next_gref, &queue_gref); list_add_tail(&gref->next_file, &queue_file); gref->users = 1; gref->file_index = op->index + i * PAGE_SIZE; gref->page = alloc_page(GFP_KERNEL|__GFP_ZERO); if (!gref->page) { rc = -ENOMEM; goto undo; } /* Grant foreign access to the page. */ rc = gnttab_grant_foreign_access(op->domid, xen_page_to_gfn(gref->page), readonly); if (rc < 0) goto undo; gref_ids[i] = gref->gref_id = rc; } /* Add to gref lists. */ mutex_lock(&gref_mutex); list_splice_tail(&queue_gref, &gref_list); list_splice_tail(&queue_file, &priv->list); mutex_unlock(&gref_mutex); return 0; undo: mutex_lock(&gref_mutex); gref_size -= (op->count - i); list_for_each_entry_safe(gref, next, &queue_file, next_file) { list_del(&gref->next_file); __del_gref(gref); } mutex_unlock(&gref_mutex); return rc;} static void __del_gref(struct gntalloc_gref *gref){ if (gref->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) { uint8_t *tmp = kmap_local_page(gref->page); tmp[gref->notify.pgoff] = 0; kunmap_local(tmp); } if (gref->notify.flags & UNMAP_NOTIFY_SEND_EVENT) { notify_remote_via_evtchn(gref->notify.event); evtchn_put(gref->notify.event); } gref->notify.flags = 0; if (gref->gref_id) { if (gref->page) gnttab_end_foreign_access(gref->gref_id, gref->page); else gnttab_free_grant_reference(gref->gref_id); } gref_size--; list_del(&gref->next_gref); kfree(gref);} /* finds contiguous grant references in a file, returns the first */static struct gntalloc_gref *find_grefs(struct gntalloc_file_private_data *priv, uint64_t index, uint32_t count){ struct gntalloc_gref *rv = NULL, *gref; list_for_each_entry(gref, &priv->list, next_file) { if (gref->file_index == index && !rv) rv = gref; if (rv) { if (gref->file_index != index) return NULL; index += PAGE_SIZE; count--; if (count == 0) return rv; } } return NULL;} /* * ------------------------------------- * File operations. * ------------------------------------- */static int gntalloc_open(struct inode *inode, struct file *filp){ struct gntalloc_file_private_data *priv; priv = kzalloc_obj(*priv); if (!priv) goto out_nomem; INIT_LIST_HEAD(&priv->list); filp->private_data = priv; pr_debug("%s: priv %p\n", __func__, priv); return 0; out_nomem: return -ENOMEM;} static int gntalloc_release(struct inode *inode, struct file *filp){ struct gntalloc_file_private_data *priv = filp->private_data; struct gntalloc_gref *gref; pr_debug("%s: priv %p\n", __func__, priv); mutex_lock(&gref_mutex); while (!list_empty(&priv->list)) { gref = list_entry(priv->list.next, struct gntalloc_gref, next_file); list_del(&gref->next_file); gref->users--; if (gref->users == 0) __del_gref(gref); } kfree(priv); mutex_unlock(&gref_mutex); return 0;} static long gntalloc_ioctl_alloc(struct gntalloc_file_private_data *priv, struct ioctl_gntalloc_alloc_gref __user *arg){ int rc = 0; struct ioctl_gntalloc_alloc_gref op; uint32_t *gref_ids; unsigned int limit_snapshot; pr_debug("%s: priv %p\n", __func__, priv); if (copy_from_user(&op, arg, sizeof(op))) { rc = -EFAULT; goto out; } limit_snapshot = READ_ONCE(limit); if (op.count > limit_snapshot) { rc = -ENOSPC; goto out; } gref_ids = kcalloc(op.count, sizeof(gref_ids[0]), GFP_KERNEL); if (!gref_ids) { rc = -ENOMEM; goto out; } mutex_lock(&gref_mutex); /* Clean up pages that were at zero (local) users but were still mapped * by remote domains. Since those pages count towards the limit that we * are about to enforce, removing them here is a good idea. */ do_cleanup(); limit_snapshot = READ_ONCE(limit); if (gref_size > limit_snapshot || op.count > limit_snapshot - gref_size) { mutex_unlock(&gref_mutex); rc = -ENOSPC; goto out_free; } gref_size += op.count; op.index = priv->index; priv->index += (uint64_t)op.count * PAGE_SIZE; mutex_unlock(&gref_mutex); rc = add_grefs(&op, gref_ids, priv); if (rc < 0) goto out_free; /* Once we finish add_grefs, it is unsafe to touch the new reference, * since it is possible for a concurrent ioctl to remove it (by guessing * its index). If the userspace application doesn't provide valid memory * to write the IDs to, then it will need to close the file in order to * release - which it will do by segfaulting when it tries to access the * IDs to close them. */ if (copy_to_user(arg, &op, sizeof(op))) { rc = -EFAULT; goto out_free; } if (copy_to_user(arg->gref_ids_flex, gref_ids, sizeof(gref_ids[0]) * op.count)) { rc = -EFAULT; goto out_free; } out_free: kfree(gref_ids);out: return rc;} static long gntalloc_ioctl_dealloc(struct gntalloc_file_private_data *priv, void __user *arg){ int i, rc = 0; struct ioctl_gntalloc_dealloc_gref op; struct gntalloc_gref *gref, *n; pr_debug("%s: priv %p\n", __func__, priv); if (copy_from_user(&op, arg, sizeof(op))) { rc = -EFAULT; goto dealloc_grant_out; } mutex_lock(&gref_mutex); gref = find_grefs(priv, op.index, op.count); if (gref) { /* Remove from the file list only, and decrease reference count. * The later call to do_cleanup() will remove from gref_list and * free the memory if the pages aren't mapped anywhere. */ for (i = 0; i < op.count; i++) { n = list_entry(gref->next_file.next, struct gntalloc_gref, next_file); list_del(&gref->next_file); gref->users--; gref = n; } } else { rc = -EINVAL; } do_cleanup(); mutex_unlock(&gref_mutex);dealloc_grant_out: return rc;} static long gntalloc_ioctl_unmap_notify(struct gntalloc_file_private_data *priv, void __user *arg){ struct ioctl_gntalloc_unmap_notify op; struct gntalloc_gref *gref; uint64_t index; int pgoff; int rc; if (copy_from_user(&op, arg, sizeof(op))) return -EFAULT; index = op.index & ~(PAGE_SIZE - 1); pgoff = op.index & (PAGE_SIZE - 1); mutex_lock(&gref_mutex); gref = find_grefs(priv, index, 1); if (!gref) { rc = -ENOENT; goto unlock_out; } if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT)) { rc = -EINVAL; goto unlock_out; } /* 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)) { rc = -EINVAL; goto unlock_out; } } if (gref->notify.flags & UNMAP_NOTIFY_SEND_EVENT) evtchn_put(gref->notify.event); gref->notify.flags = op.action; gref->notify.pgoff = pgoff; gref->notify.event = op.event_channel_port; rc = 0; unlock_out: mutex_unlock(&gref_mutex); return rc;} static long gntalloc_ioctl(struct file *filp, unsigned int cmd, unsigned long arg){ struct gntalloc_file_private_data *priv = filp->private_data; switch (cmd) { case IOCTL_GNTALLOC_ALLOC_GREF: return gntalloc_ioctl_alloc(priv, (void __user *)arg); case IOCTL_GNTALLOC_DEALLOC_GREF: return gntalloc_ioctl_dealloc(priv, (void __user *)arg); case IOCTL_GNTALLOC_SET_UNMAP_NOTIFY: return gntalloc_ioctl_unmap_notify(priv, (void __user *)arg); default: return -ENOIOCTLCMD; } return 0;} static void gntalloc_vma_open(struct vm_area_struct *vma){ struct gntalloc_vma_private_data *priv = vma->vm_private_data; if (!priv) return; mutex_lock(&gref_mutex); priv->users++; mutex_unlock(&gref_mutex);} static void gntalloc_vma_close(struct vm_area_struct *vma){ struct gntalloc_vma_private_data *priv = vma->vm_private_data; struct gntalloc_gref *gref, *next; int i; if (!priv) return; mutex_lock(&gref_mutex); priv->users--; if (priv->users == 0) { gref = priv->gref; for (i = 0; i < priv->count; i++) { gref->users--; next = list_entry(gref->next_gref.next, struct gntalloc_gref, next_gref); if (gref->users == 0) __del_gref(gref); gref = next; } kfree(priv); } mutex_unlock(&gref_mutex);} static const struct vm_operations_struct gntalloc_vmops = { .open = gntalloc_vma_open, .close = gntalloc_vma_close,}; static int gntalloc_mmap(struct file *filp, struct vm_area_struct *vma)Lines 1–500 of 607. 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/****************************************************************************** * gntalloc.c * * Device for creating grant references (in user-space) that may be shared * with other domains. * * 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 */ /* * This driver exists to allow userspace programs in Linux to allocate kernel * memory that will later be shared with another domain. Without this device, * Linux userspace programs cannot create grant references. * * How this stuff works: * X -> granting a page to Y * Y -> mapping the grant from X * * 1. X uses the gntalloc device to allocate a page of kernel memory, P. * 2. X creates an entry in the grant table that says domid(Y) can access P. * This is done without a hypercall unless the grant table needs expansion. * 3. X gives the grant reference identifier, GREF, to Y. * 4. Y maps the page, either directly into kernel memory for use in a backend * driver, or via a the gntdev device to map into the address space of an * application running in Y. This is the first point at which Xen does any * tracking of the page. * 5. A program in X mmap()s a segment of the gntalloc device that corresponds * to the shared page, and can now communicate with Y over the shared page. * * * NOTE TO USERSPACE LIBRARIES: * The grant allocation and mmap()ing are, naturally, two separate operations. * You set up the sharing by calling the create ioctl() and then the mmap(). * Teardown requires munmap() and either close() or ioctl(). * * WARNING: Since Xen does not allow a guest to forcibly end the use of a grant * reference, this device can be used to consume kernel memory by leaving grant * references mapped by another domain when an application exits. Therefore, * there is a global limit on the number of pages that can be allocated. When * all references to the page are unmapped, it will be freed during the next * grant operation. */ #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt #include <linux/atomic.h> #include <linux/module.h> #include <linux/miscdevice.h> #include <linux/kernel.h> #include <linux/init.h> #include <linux/slab.h> #include <linux/fs.h> #include <linux/device.h> #include <linux/mm.h> #include <linux/uaccess.h> #include <linux/types.h> #include <linux/list.h> #include <linux/highmem.h> #include <xen/xen.h> #include <xen/page.h> #include <xen/grant_table.h> #include <xen/gntalloc.h> #include <xen/events.h> static unsigned int limit = 1024; module_param(limit, uint, 0644); MODULE_PARM_DESC(limit, "Maximum number of grants that may be allocated by " "the gntalloc device"); static LIST_HEAD(gref_list); static DEFINE_MUTEX(gref_mutex); static unsigned int gref_size; struct notify_info { uint16_t pgoff:12; /* Bits 0-11: Offset of the byte to clear */ uint16_t flags:2; /* Bits 12-13: Unmap notification flags */ int event; /* Port (event channel) to notify */ }; /* Metadata on a grant reference. */ struct gntalloc_gref { struct list_head next_gref; /* list entry gref_list */ struct list_head next_file; /* list entry file->list, if open */ struct page *page; /* The shared page */ uint64_t file_index; /* File offset for mmap() */ unsigned int users; /* Use count - when zero, waiting on Xen */ grant_ref_t gref_id; /* The grant reference number */ struct notify_info notify; /* Unmap notification */ }; struct gntalloc_file_private_data { struct list_head list; uint64_t index; }; struct gntalloc_vma_private_data { struct gntalloc_gref *gref; int users; int count; }; static void __del_gref(struct gntalloc_gref *gref); static void do_cleanup(void) { struct gntalloc_gref *gref, *n; list_for_each_entry_safe(gref, n, &gref_list, next_gref) { if (!gref->users) __del_gref(gref); } } static int add_grefs(struct ioctl_gntalloc_alloc_gref *op, uint32_t *gref_ids, struct gntalloc_file_private_data *priv) { int i, rc, readonly; LIST_HEAD(queue_gref); LIST_HEAD(queue_file); struct gntalloc_gref *gref, *next; readonly = !(op->flags & GNTALLOC_FLAG_WRITABLE); for (i = 0; i < op->count; i++) { gref = kzalloc_obj(*gref); if (!gref) { rc = -ENOMEM; goto undo; } list_add_tail(&gref->next_gref, &queue_gref); list_add_tail(&gref->next_file, &queue_file); gref->users = 1; gref->file_index = op->index + i * PAGE_SIZE; gref->page = alloc_page(GFP_KERNEL|__GFP_ZERO); if (!gref->page) { rc = -ENOMEM; goto undo; } /* Grant foreign access to the page. */ rc = gnttab_grant_foreign_access(op->domid, xen_page_to_gfn(gref->page), readonly); if (rc < 0) goto undo; gref_ids[i] = gref->gref_id = rc; } /* Add to gref lists. */ mutex_lock(&gref_mutex); list_splice_tail(&queue_gref, &gref_list); list_splice_tail(&queue_file, &priv->list); mutex_unlock(&gref_mutex); return 0; undo: mutex_lock(&gref_mutex); gref_size -= (op->count - i); list_for_each_entry_safe(gref, next, &queue_file, next_file) { list_del(&gref->next_file); __del_gref(gref); } mutex_unlock(&gref_mutex); return rc; } static void __del_gref(struct gntalloc_gref *gref) { if (gref->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) { uint8_t *tmp = kmap_local_page(gref->page); tmp[gref->notify.pgoff] = 0; kunmap_local(tmp); } if (gref->notify.flags & UNMAP_NOTIFY_SEND_EVENT) { notify_remote_via_evtchn(gref->notify.event); evtchn_put(gref->notify.event); } gref->notify.flags = 0; if (gref->gref_id) { if (gref->page) gnttab_end_foreign_access(gref->gref_id, gref->page); else gnttab_free_grant_reference(gref->gref_id); } gref_size--; list_del(&gref->next_gref); kfree(gref); } /* finds contiguous grant references in a file, returns the first */ static struct gntalloc_gref *find_grefs(struct gntalloc_file_private_data *priv, uint64_t index, uint32_t count) { struct gntalloc_gref *rv = NULL, *gref; list_for_each_entry(gref, &priv->list, next_file) { if (gref->file_index == index && !rv) rv = gref; if (rv) { if (gref->file_index != index) return NULL; index += PAGE_SIZE; count--; if (count == 0) return rv; } } return NULL; } /* * ------------------------------------- * File operations. * ------------------------------------- */ static int gntalloc_open(struct inode *inode, struct file *filp) { struct gntalloc_file_private_data *priv; priv = kzalloc_obj(*priv); if (!priv) goto out_nomem; INIT_LIST_HEAD(&priv->list); filp->private_data = priv; pr_debug("%s: priv %p\n", __func__, priv); return 0; out_nomem: return -ENOMEM; } static int gntalloc_release(struct inode *inode, struct file *filp) { struct gntalloc_file_private_data *priv = filp->private_data; struct gntalloc_gref *gref; pr_debug("%s: priv %p\n", __func__, priv); mutex_lock(&gref_mutex); while (!list_empty(&priv->list)) { gref = list_entry(priv->list.next, struct gntalloc_gref, next_file); list_del(&gref->next_file); gref->users--; if (gref->users == 0) __del_gref(gref); } kfree(priv); mutex_unlock(&gref_mutex); return 0; } static long gntalloc_ioctl_alloc(struct gntalloc_file_private_data *priv, struct ioctl_gntalloc_alloc_gref __user *arg) { int rc = 0; struct ioctl_gntalloc_alloc_gref op; uint32_t *gref_ids; unsigned int limit_snapshot; pr_debug("%s: priv %p\n", __func__, priv); if (copy_from_user(&op, arg, sizeof(op))) { rc = -EFAULT; goto out; } limit_snapshot = READ_ONCE(limit); if (op.count > limit_snapshot) { rc = -ENOSPC; goto out; } gref_ids = kcalloc(op.count, sizeof(gref_ids[0]), GFP_KERNEL); if (!gref_ids) { rc = -ENOMEM; goto out; } mutex_lock(&gref_mutex); /* Clean up pages that were at zero (local) users but were still mapped * by remote domains. Since those pages count towards the limit that we * are about to enforce, removing them here is a good idea. */ do_cleanup(); limit_snapshot = READ_ONCE(limit); if (gref_size > limit_snapshot || op.count > limit_snapshot - gref_size) { mutex_unlock(&gref_mutex); rc = -ENOSPC; goto out_free; } gref_size += op.count; op.index = priv->index; priv->index += (uint64_t)op.count * PAGE_SIZE; mutex_unlock(&gref_mutex); rc = add_grefs(&op, gref_ids, priv); if (rc < 0) goto out_free; /* Once we finish add_grefs, it is unsafe to touch the new reference, * since it is possible for a concurrent ioctl to remove it (by guessing * its index). If the userspace application doesn't provide valid memory * to write the IDs to, then it will need to close the file in order to * release - which it will do by segfaulting when it tries to access the * IDs to close them. */ if (copy_to_user(arg, &op, sizeof(op))) { rc = -EFAULT; goto out_free; } if (copy_to_user(arg->gref_ids_flex, gref_ids, sizeof(gref_ids[0]) * op.count)) { rc = -EFAULT; goto out_free; } out_free: kfree(gref_ids); out: return rc; } static long gntalloc_ioctl_dealloc(struct gntalloc_file_private_data *priv, void __user *arg) { int i, rc = 0; struct ioctl_gntalloc_dealloc_gref op; struct gntalloc_gref *gref, *n; pr_debug("%s: priv %p\n", __func__, priv); if (copy_from_user(&op, arg, sizeof(op))) { rc = -EFAULT; goto dealloc_grant_out; } mutex_lock(&gref_mutex); gref = find_grefs(priv, op.index, op.count); if (gref) { /* Remove from the file list only, and decrease reference count. * The later call to do_cleanup() will remove from gref_list and * free the memory if the pages aren't mapped anywhere. */ for (i = 0; i < op.count; i++) { n = list_entry(gref->next_file.next, struct gntalloc_gref, next_file); list_del(&gref->next_file); gref->users--; gref = n; } } else { rc = -EINVAL; } do_cleanup(); mutex_unlock(&gref_mutex); dealloc_grant_out: return rc; } static long gntalloc_ioctl_unmap_notify(struct gntalloc_file_private_data *priv, void __user *arg) { struct ioctl_gntalloc_unmap_notify op; struct gntalloc_gref *gref; uint64_t index; int pgoff; int rc; if (copy_from_user(&op, arg, sizeof(op))) return -EFAULT; index = op.index & ~(PAGE_SIZE - 1); pgoff = op.index & (PAGE_SIZE - 1); mutex_lock(&gref_mutex); gref = find_grefs(priv, index, 1); if (!gref) { rc = -ENOENT; goto unlock_out; } if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT)) { rc = -EINVAL; goto unlock_out; } /* 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)) { rc = -EINVAL; goto unlock_out; } } if (gref->notify.flags & UNMAP_NOTIFY_SEND_EVENT) evtchn_put(gref->notify.event); gref->notify.flags = op.action; gref->notify.pgoff = pgoff; gref->notify.event = op.event_channel_port; rc = 0; unlock_out: mutex_unlock(&gref_mutex); return rc; } static long gntalloc_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) { struct gntalloc_file_private_data *priv = filp->private_data; switch (cmd) { case IOCTL_GNTALLOC_ALLOC_GREF: return gntalloc_ioctl_alloc(priv, (void __user *)arg); case IOCTL_GNTALLOC_DEALLOC_GREF: return gntalloc_ioctl_dealloc(priv, (void __user *)arg); case IOCTL_GNTALLOC_SET_UNMAP_NOTIFY: return gntalloc_ioctl_unmap_notify(priv, (void __user *)arg); default: return -ENOIOCTLCMD; } return 0; } static void gntalloc_vma_open(struct vm_area_struct *vma) { struct gntalloc_vma_private_data *priv = vma->vm_private_data; if (!priv) return; mutex_lock(&gref_mutex); priv->users++; mutex_unlock(&gref_mutex); } static void gntalloc_vma_close(struct vm_area_struct *vma) { struct gntalloc_vma_private_data *priv = vma->vm_private_data; struct gntalloc_gref *gref, *next; int i; if (!priv) return; mutex_lock(&gref_mutex); priv->users--; if (priv->users == 0) { gref = priv->gref; for (i = 0; i < priv->count; i++) { gref->users--; next = list_entry(gref->next_gref.next, struct gntalloc_gref, next_gref); if (gref->users == 0) __del_gref(gref); gref = next; } kfree(priv); } mutex_unlock(&gref_mutex); } static const struct vm_operations_struct gntalloc_vmops = { .open = gntalloc_vma_open, .close = gntalloc_vma_close, }; static int gntalloc_mmap(struct file *filp, struct vm_area_struct *vma)