/******************************************************************************
* Xen balloon driver - enables returning/claiming memory to/from Xen.
*
* Copyright (c) 2003, B Dragovic
* Copyright (c) 2003-2004, M Williamson, K Fraser
* Copyright (c) 2005 Dan M. Smith, IBM Corporation
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation; or, when distributed
* separately from the Linux kernel or incorporated into other
* software packages, subject to the following license:
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this source file (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use, copy, modify,
* merge, publish, distribute, sublicense, and/or sell copies of the Software,
* and to permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sysdev.h>
#include <linux/capability.h>
#include <xen/xen.h>
#include <xen/interface/xen.h>
#include <xen/balloon.h>
#include <xen/xenbus.h>
#include <xen/features.h>
#include <xen/page.h>
#define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10))
#define BALLOON_CLASS_NAME "xen_memory"
static struct sys_device balloon_sysdev;
static int register_balloon(struct sys_device *sysdev);
static struct xenbus_watch target_watch =
{
.node = "memory/target"
};
/* React to a change in the target key */
static void watch_target(struct xenbus_watch *watch,
const char **vec, unsigned int len)
{
unsigned long long new_target;
int err;
err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target);
if (err != 1) {
/* This is ok (for domain0 at least) - so just return */
return;
}
/* The given memory/target value is in KiB, so it needs converting to
* pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10.
*/
balloon_set_new_target(new_target >> (PAGE_SHIFT - 10));
}
static int balloon_init_watcher(struct notifier_block *notifier,
unsigned long event,
void *data)
{
int err;
err = register_xenbus_watch(&target_watch);
if (err)
printk(KERN_ERR "Failed to set balloon watcher\n");
return NOTIFY_DONE;
}
static struct notifier_block xenstore_notifier;
static int __init balloon_init(void)
{
if (!xen_domain())
return -ENODEV;
pr_info("xen-balloon: Initialising balloon driver.\n");
register_balloon(&balloon_sysdev);
target_watch.callback = watch_target;
xenstore_notifier.notifier_call = balloon_init_watcher;
register_xenstore_notifier(&xenstore_notifier);
return 0;
}
subsys_initcall(balloon_init);
static void balloon_exit(void)
{
/* XXX - release balloon here */
return;
}
module_exit(balloon_exit);
#define BALLOON_SHOW(name, format, args...) \
static ssize_t show_##name(struct sys_device *dev, \
struct sysdev_attribute *attr, \
char *buf) \
{ \
return sprintf(buf, format, ##args); \
} \
static SYSDEV_ATTR(name, S_IRUGO, show_##name, NULL)
BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages));
BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low));
BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high));
static SYSDEV_ULONG_ATTR(schedule_delay, 0444, balloon_stats.schedule_delay);
static SYSDEV_ULONG_ATTR(max_schedule_delay, 0644, balloon_stats.max_schedule_delay);
static SYSDEV_ULONG_ATTR(retry_count, 0444, balloon_stats.retry_count);
static SYSDEV_ULONG_ATTR(max_retry_count, 0644, balloon_stats.max_retry_count);
static ssize_t show_target_kb(struct sys_device *dev, struct sysdev_attribute *attr,
char *buf)
{
return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages));
}
static ssize_t store_target_kb(struct sys_device *dev,
struct sysdev_attribute *attr,
const char *buf,
size_t count)
{
char *endchar;
unsigned long long target_bytes;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
target_bytes = simple_strtoull(buf, &endchar, 0) * 1024;
balloon_set_new_target(target_bytes >> PAGE_SHIFT);
return count;
}
static SYSDEV_ATTR(target_kb, S_IRUGO | S_IWUSR,
show_target_kb, store_target_kb);
static ssize_t show_target(struct sys_device *dev, struct sysdev_attribute *attr,
char *buf)
{
return sprintf(buf, "%llu\n",
(unsigned long long)balloon_stats.target_pages
<< PAGE_SHIFT);
}
static ssize_t store_target(struct sys_device *dev,
struct sysdev_attribute *attr,
const char *buf,
size_t count)
{
char *endchar;
unsigned long long target_bytes;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
target_bytes = memparse(buf, &endchar);
balloon_set_new_target(target_bytes >> PAGE_SHIFT);
return count;
}
static SYSDEV_ATTR(target, S_IRUGO | S_IWUSR,
show_target, store_target);
static struct sysdev_attribute *balloon_attrs[] = {
&attr_target_kb,
&attr_target,
&attr_schedule_delay.attr,
&attr_max_schedule_delay.attr,
&attr_retry_count.attr,
&attr_max_retry_count.attr
};
static struct attribute *balloon_info_attrs[] = {
&attr_current_kb.attr,
&attr_low_kb.attr,
&attr_high_kb.attr,
NULL
};
static struct attribute_group balloon_info_group = {
.name = "info",
.attrs = balloon_info_attrs
};
static struct sysdev_class balloon_sysdev_class = {
.name = BALLOON_CLASS_NAME
};
static int register_balloon(struct sys_device *sysdev)
{
int i, error;
error = sysdev_class_register(&balloon_sysdev_class);
if (error)
return error;
sysdev->id = 0;
sysdev->cls = &balloon_sysdev_class;
error = sysdev_register(sysdev);
if (error) {
sysdev_class_unregister(&balloon_sysdev_class);
return error;
}
for (i = 0; i < ARRAY_SIZE(balloon_attrs); i++) {
error = sysdev_create_file(sysdev, balloon_attrs[i]);
if (error)
goto fail;
}
error = sysfs_create_group(&sysdev->kobj, &balloon_info_group);
if (error)
goto fail;
return 0;
fail:
while (--i >= 0)
sysdev_remove_file(sysdev, balloon_attrs[i]);
sysdev_unregister(sysdev);
sysdev_class_unregister(&balloon_sysdev_class);
return error;
}
MODULE_LICENSE("GPL");
