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>
diff --git a/drivers/xen/gntalloc.c b/drivers/xen/gntalloc.c
index d06bf2b..a7ffdfe 100644
--- a/drivers/xen/gntalloc.c
+++ b/drivers/xen/gntalloc.c
@@ -60,11 +60,13 @@
#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 int limit = 1024;
module_param(limit, int, 0644);
@@ -75,6 +77,12 @@
static DEFINE_SPINLOCK(gref_lock);
static 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 */
@@ -83,6 +91,7 @@
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 {
@@ -164,6 +173,16 @@
static void __del_gref(struct gntalloc_gref *gref)
{
+ if (gref->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
+ uint8_t *tmp = kmap(gref->page);
+ tmp[gref->notify.pgoff] = 0;
+ kunmap(gref->page);
+ }
+ if (gref->notify.flags & UNMAP_NOTIFY_SEND_EVENT)
+ notify_remote_via_evtchn(gref->notify.event);
+
+ gref->notify.flags = 0;
+
if (gref->gref_id > 0) {
if (gnttab_query_foreign_access(gref->gref_id))
return;
@@ -349,6 +368,43 @@
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);
+
+ spin_lock(&gref_lock);
+
+ 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;
+ }
+
+ gref->notify.flags = op.action;
+ gref->notify.pgoff = pgoff;
+ gref->notify.event = op.event_channel_port;
+ rc = 0;
+ unlock_out:
+ spin_unlock(&gref_lock);
+ return rc;
+}
+
static long gntalloc_ioctl(struct file *filp, unsigned int cmd,
unsigned long arg)
{
@@ -361,6 +417,9 @@
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;
}
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index bcaf797..9694a1a 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -37,6 +37,7 @@
#include <xen/xen.h>
#include <xen/grant_table.h>
#include <xen/gntdev.h>
+#include <xen/events.h>
#include <asm/xen/hypervisor.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/page.h>
@@ -63,6 +64,13 @@
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;
@@ -71,6 +79,7 @@
int flags;
int is_mapped;
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;
@@ -165,7 +174,7 @@
list_for_each_entry(map, &priv->maps, next) {
if (map->index != index)
continue;
- if (map->count != count)
+ if (count && map->count != count)
continue;
return map;
}
@@ -184,6 +193,10 @@
atomic_sub(map->count, &pages_mapped);
+ if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) {
+ notify_remote_via_evtchn(map->notify.event);
+ }
+
if (map->pages) {
if (!use_ptemod)
unmap_grant_pages(map, 0, map->count);
@@ -274,6 +287,16 @@
{
int i, err = 0;
+ if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
+ int pgno = (map->notify.addr >> PAGE_SHIFT);
+ if (pgno >= offset && pgno < offset + pages) {
+ uint8_t *tmp = kmap(map->pages[pgno]);
+ tmp[map->notify.addr & (PAGE_SIZE-1)] = 0;
+ kunmap(map->pages[pgno]);
+ map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
+ }
+ }
+
pr_debug("map %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages, pages);
if (err)
@@ -519,6 +542,39 @@
return 0;
}
+static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
+{
+ struct ioctl_gntdev_unmap_notify op;
+ struct grant_map *map;
+ int rc;
+
+ if (copy_from_user(&op, u, sizeof(op)))
+ return -EFAULT;
+
+ if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT))
+ return -EINVAL;
+
+ spin_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:
+ 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:
+ spin_unlock(&priv->lock);
+ return rc;
+}
+
static long gntdev_ioctl(struct file *flip,
unsigned int cmd, unsigned long arg)
{
@@ -535,6 +591,9 @@
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);
+
default:
pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
return -ENOIOCTLCMD;