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xen/gntalloc,gntdev: Add unmap notify ioctl

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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
2011-02-03 12:19:04 -05:00
committed by Konrad Rzeszutek Wilk
parent dd3140588d
commit bdc612dc69
4 changed files with 182 additions and 1 deletions
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59
drivers/xen/gntalloc.c
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@@ -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 LIST_HEAD(gref_list);
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 @@ struct gntalloc_gref {
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 @@ undo:
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 @@ 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);
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 @@ static long gntalloc_ioctl(struct file *filp, unsigned int cmd,
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;
}