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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
34
35#include <linux/kernel.h>
36#include <linux/module.h>
37#include <linux/capability.h>
38
39#include <xen/xen.h>
40#include <xen/interface/xen.h>
41#include <xen/balloon.h>
42#include <xen/xenbus.h>
43#include <xen/features.h>
44#include <xen/page.h>
45
46#define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10))
47
48#define BALLOON_CLASS_NAME "xen_memory"
49
50static struct device balloon_dev;
51
52static int register_balloon(struct device *dev);
53
54/* React to a change in the target key */
55static void watch_target(struct xenbus_watch *watch,
56			 const char **vec, unsigned int len)
57{
58	unsigned long long new_target;
59	int err;
60
61	err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target);
62	if (err != 1) {
63		/* This is ok (for domain0 at least) - so just return */
64		return;
65	}
66
67	/* The given memory/target value is in KiB, so it needs converting to
68	 * pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10.
69	 */
70	balloon_set_new_target(new_target >> (PAGE_SHIFT - 10));
71}
72static struct xenbus_watch target_watch = {
73	.node = "memory/target",
74	.callback = watch_target,
75};
76
77
78static int balloon_init_watcher(struct notifier_block *notifier,
79				unsigned long event,
80				void *data)
81{
82	int err;
83
84	err = register_xenbus_watch(&target_watch);
85	if (err)
86		pr_err("Failed to set balloon watcher\n");
87
88	return NOTIFY_DONE;
89}
90
91static struct notifier_block xenstore_notifier = {
92	.notifier_call = balloon_init_watcher,
93};
94
95static int __init balloon_init(void)
96{
97	if (!xen_domain())
98		return -ENODEV;
99
100	pr_info("Initialising balloon driver\n");
101
102	register_balloon(&balloon_dev);
103
104	register_xen_selfballooning(&balloon_dev);
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 device *dev,			\
122				   struct device_attribute *attr,	\
123				   char *buf)				\
124	{								\
125		return sprintf(buf, format, ##args);			\
126	}								\
127	static DEVICE_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 DEVICE_ULONG_ATTR(schedule_delay, 0444, balloon_stats.schedule_delay);
134static DEVICE_ULONG_ATTR(max_schedule_delay, 0644, balloon_stats.max_schedule_delay);
135static DEVICE_ULONG_ATTR(retry_count, 0444, balloon_stats.retry_count);
136static DEVICE_ULONG_ATTR(max_retry_count, 0644, balloon_stats.max_retry_count);
137
138static ssize_t show_target_kb(struct device *dev, struct device_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 device *dev,
145			       struct device_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 DEVICE_ATTR(target_kb, S_IRUGO | S_IWUSR,
163		   show_target_kb, store_target_kb);
164
165
166static ssize_t show_target(struct device *dev, struct device_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 device *dev,
175			    struct device_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 DEVICE_ATTR(target, S_IRUGO | S_IWUSR,
193		   show_target, store_target);
194
195
196static struct attribute *balloon_attrs[] = {
197	&dev_attr_target_kb.attr,
198	&dev_attr_target.attr,
199	&dev_attr_schedule_delay.attr.attr,
200	&dev_attr_max_schedule_delay.attr.attr,
201	&dev_attr_retry_count.attr.attr,
202	&dev_attr_max_retry_count.attr.attr,
203	NULL
204};
205
206static const struct attribute_group balloon_group = {
207	.attrs = balloon_attrs
208};
209
210static struct attribute *balloon_info_attrs[] = {
211	&dev_attr_current_kb.attr,
212	&dev_attr_low_kb.attr,
213	&dev_attr_high_kb.attr,
214	NULL
215};
216
217static const struct attribute_group balloon_info_group = {
218	.name = "info",
219	.attrs = balloon_info_attrs
220};
221
222static const struct attribute_group *balloon_groups[] = {
223	&balloon_group,
224	&balloon_info_group,
225	NULL
226};
227
228static struct bus_type balloon_subsys = {
229	.name = BALLOON_CLASS_NAME,
230	.dev_name = BALLOON_CLASS_NAME,
231};
232
233static int register_balloon(struct device *dev)
234{
235	int error;
236
237	error = subsys_system_register(&balloon_subsys, NULL);
238	if (error)
239		return error;
240
241	dev->id = 0;
242	dev->bus = &balloon_subsys;
243	dev->groups = balloon_groups;
244
245	error = device_register(dev);
246	if (error) {
247		bus_unregister(&balloon_subsys);
248		return error;
249	}
250
251	return 0;
252}
253
254MODULE_LICENSE("GPL");
255