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/drivers/xen/xen-balloon.c

https://bitbucket.org/cyanogenmod/android_kernel_asus_tf300t
C | 258 lines | 166 code | 55 blank | 37 comment | 12 complexity | f385aa8740cd95a63f7f41898492ca5e MD5 | raw file
Possible License(s): LGPL-2.0, AGPL-1.0, GPL-2.0
  1/******************************************************************************
  2 * Xen balloon driver - enables returning/claiming memory to/from Xen.
  3 *
  4 * Copyright (c) 2003, B Dragovic
  5 * Copyright (c) 2003-2004, M Williamson, K Fraser
  6 * Copyright (c) 2005 Dan M. Smith, IBM Corporation
  7 *
  8 * This program is free software; you can redistribute it and/or
  9 * modify it under the terms of the GNU General Public License version 2
 10 * as published by the Free Software Foundation; or, when distributed
 11 * separately from the Linux kernel or incorporated into other
 12 * software packages, subject to the following license:
 13 *
 14 * Permission is hereby granted, free of charge, to any person obtaining a copy
 15 * of this source file (the "Software"), to deal in the Software without
 16 * restriction, including without limitation the rights to use, copy, modify,
 17 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
 18 * and to permit persons to whom the Software is furnished to do so, subject to
 19 * the following conditions:
 20 *
 21 * The above copyright notice and this permission notice shall be included in
 22 * all copies or substantial portions of the Software.
 23 *
 24 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 25 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 26 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 27 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 28 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 29 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 30 * IN THE SOFTWARE.
 31 */
 32
 33#include <linux/kernel.h>
 34#include <linux/module.h>
 35#include <linux/sysdev.h>
 36#include <linux/capability.h>
 37
 38#include <xen/xen.h>
 39#include <xen/interface/xen.h>
 40#include <xen/balloon.h>
 41#include <xen/xenbus.h>
 42#include <xen/features.h>
 43#include <xen/page.h>
 44
 45#define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10))
 46
 47#define BALLOON_CLASS_NAME "xen_memory"
 48
 49static struct sys_device balloon_sysdev;
 50
 51static int register_balloon(struct sys_device *sysdev);
 52
 53static struct xenbus_watch target_watch =
 54{
 55	.node = "memory/target"
 56};
 57
 58/* React to a change in the target key */
 59static void watch_target(struct xenbus_watch *watch,
 60			 const char **vec, unsigned int len)
 61{
 62	unsigned long long new_target;
 63	int err;
 64
 65	err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target);
 66	if (err != 1) {
 67		/* This is ok (for domain0 at least) - so just return */
 68		return;
 69	}
 70
 71	/* The given memory/target value is in KiB, so it needs converting to
 72	 * pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10.
 73	 */
 74	balloon_set_new_target(new_target >> (PAGE_SHIFT - 10));
 75}
 76
 77static int balloon_init_watcher(struct notifier_block *notifier,
 78				unsigned long event,
 79				void *data)
 80{
 81	int err;
 82
 83	err = register_xenbus_watch(&target_watch);
 84	if (err)
 85		printk(KERN_ERR "Failed to set balloon watcher\n");
 86
 87	return NOTIFY_DONE;
 88}
 89
 90static struct notifier_block xenstore_notifier;
 91
 92static int __init balloon_init(void)
 93{
 94	if (!xen_domain())
 95		return -ENODEV;
 96
 97	pr_info("xen-balloon: Initialising balloon driver.\n");
 98
 99	register_balloon(&balloon_sysdev);
100
101	register_xen_selfballooning(&balloon_sysdev);
102
103	target_watch.callback = watch_target;
104	xenstore_notifier.notifier_call = balloon_init_watcher;
105
106	register_xenstore_notifier(&xenstore_notifier);
107
108	return 0;
109}
110subsys_initcall(balloon_init);
111
112static void balloon_exit(void)
113{
114    /* XXX - release balloon here */
115    return;
116}
117
118module_exit(balloon_exit);
119
120#define BALLOON_SHOW(name, format, args...)				\
121	static ssize_t show_##name(struct sys_device *dev,		\
122				   struct sysdev_attribute *attr,	\
123				   char *buf)				\
124	{								\
125		return sprintf(buf, format, ##args);			\
126	}								\
127	static SYSDEV_ATTR(name, S_IRUGO, show_##name, NULL)
128
129BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages));
130BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low));
131BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high));
132
133static SYSDEV_ULONG_ATTR(schedule_delay, 0444, balloon_stats.schedule_delay);
134static SYSDEV_ULONG_ATTR(max_schedule_delay, 0644, balloon_stats.max_schedule_delay);
135static SYSDEV_ULONG_ATTR(retry_count, 0444, balloon_stats.retry_count);
136static SYSDEV_ULONG_ATTR(max_retry_count, 0644, balloon_stats.max_retry_count);
137
138static ssize_t show_target_kb(struct sys_device *dev, struct sysdev_attribute *attr,
139			      char *buf)
140{
141	return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages));
142}
143
144static ssize_t store_target_kb(struct sys_device *dev,
145			       struct sysdev_attribute *attr,
146			       const char *buf,
147			       size_t count)
148{
149	char *endchar;
150	unsigned long long target_bytes;
151
152	if (!capable(CAP_SYS_ADMIN))
153		return -EPERM;
154
155	target_bytes = simple_strtoull(buf, &endchar, 0) * 1024;
156
157	balloon_set_new_target(target_bytes >> PAGE_SHIFT);
158
159	return count;
160}
161
162static SYSDEV_ATTR(target_kb, S_IRUGO | S_IWUSR,
163		   show_target_kb, store_target_kb);
164
165
166static ssize_t show_target(struct sys_device *dev, struct sysdev_attribute *attr,
167			      char *buf)
168{
169	return sprintf(buf, "%llu\n",
170		       (unsigned long long)balloon_stats.target_pages
171		       << PAGE_SHIFT);
172}
173
174static ssize_t store_target(struct sys_device *dev,
175			    struct sysdev_attribute *attr,
176			    const char *buf,
177			    size_t count)
178{
179	char *endchar;
180	unsigned long long target_bytes;
181
182	if (!capable(CAP_SYS_ADMIN))
183		return -EPERM;
184
185	target_bytes = memparse(buf, &endchar);
186
187	balloon_set_new_target(target_bytes >> PAGE_SHIFT);
188
189	return count;
190}
191
192static SYSDEV_ATTR(target, S_IRUGO | S_IWUSR,
193		   show_target, store_target);
194
195
196static struct sysdev_attribute *balloon_attrs[] = {
197	&attr_target_kb,
198	&attr_target,
199	&attr_schedule_delay.attr,
200	&attr_max_schedule_delay.attr,
201	&attr_retry_count.attr,
202	&attr_max_retry_count.attr
203};
204
205static struct attribute *balloon_info_attrs[] = {
206	&attr_current_kb.attr,
207	&attr_low_kb.attr,
208	&attr_high_kb.attr,
209	NULL
210};
211
212static struct attribute_group balloon_info_group = {
213	.name = "info",
214	.attrs = balloon_info_attrs
215};
216
217static struct sysdev_class balloon_sysdev_class = {
218	.name = BALLOON_CLASS_NAME
219};
220
221static int register_balloon(struct sys_device *sysdev)
222{
223	int i, error;
224
225	error = sysdev_class_register(&balloon_sysdev_class);
226	if (error)
227		return error;
228
229	sysdev->id = 0;
230	sysdev->cls = &balloon_sysdev_class;
231
232	error = sysdev_register(sysdev);
233	if (error) {
234		sysdev_class_unregister(&balloon_sysdev_class);
235		return error;
236	}
237
238	for (i = 0; i < ARRAY_SIZE(balloon_attrs); i++) {
239		error = sysdev_create_file(sysdev, balloon_attrs[i]);
240		if (error)
241			goto fail;
242	}
243
244	error = sysfs_create_group(&sysdev->kobj, &balloon_info_group);
245	if (error)
246		goto fail;
247
248	return 0;
249
250 fail:
251	while (--i >= 0)
252		sysdev_remove_file(sysdev, balloon_attrs[i]);
253	sysdev_unregister(sysdev);
254	sysdev_class_unregister(&balloon_sysdev_class);
255	return error;
256}
257
258MODULE_LICENSE("GPL");