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/errno.h>
37#include <linux/mm_types.h>
38#include <linux/init.h>
39#include <linux/capability.h>
40#include <linux/memory_hotplug.h>
41
42#include <xen/xen.h>
43#include <xen/interface/xen.h>
44#include <xen/balloon.h>
45#include <xen/xenbus.h>
46#include <xen/features.h>
47#include <xen/page.h>
48#include <xen/mem-reservation.h>
49
50#define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10))
51
52#define BALLOON_CLASS_NAME "xen_memory"
53
54#ifdef CONFIG_MEMORY_HOTPLUG
55u64 xen_saved_max_mem_size = 0;
56#endif
57
58static struct device balloon_dev;
59
60static int register_balloon(struct device *dev);
61
62/* React to a change in the target key */
63static void watch_target(struct xenbus_watch *watch,
64 const char *path, const char *token)
65{
66 unsigned long long new_target, static_max;
67 int err;
68 static bool watch_fired;
69 static long target_diff;
70
71#ifdef CONFIG_MEMORY_HOTPLUG
72 /* The balloon driver will take care of adding memory now. */
73 if (xen_saved_max_mem_size)
74 max_mem_size = xen_saved_max_mem_size;
75#endif
76
77 err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target);
78 if (err != 1) {
79 /* This is ok (for domain0 at least) - so just return */
80 return;
81 }
82
83 /* The given memory/target value is in KiB, so it needs converting to
84 * pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10.
85 */
86 new_target >>= PAGE_SHIFT - 10;
87
88 if (!watch_fired) {
89 watch_fired = true;
90
91 if ((xenbus_scanf(XBT_NIL, "memory", "static-max",
92 "%llu", &static_max) == 1) ||
93 (xenbus_scanf(XBT_NIL, "memory", "memory_static_max",
94 "%llu", &static_max) == 1))
95 static_max >>= PAGE_SHIFT - 10;
96 else
97 static_max = new_target;
98
99 target_diff = (xen_pv_domain() || xen_initial_domain()) ? 0
100 : static_max - balloon_stats.target_pages;
101 }
102
103 balloon_set_new_target(new_target - target_diff);
104}
105static struct xenbus_watch target_watch = {
106 .node = "memory/target",
107 .callback = watch_target,
108};
109
110
111static int balloon_init_watcher(struct notifier_block *notifier,
112 unsigned long event,
113 void *data)
114{
115 int err;
116
117 err = register_xenbus_watch(&target_watch);
118 if (err)
119 pr_err("Failed to set balloon watcher\n");
120
121 return NOTIFY_DONE;
122}
123
124static struct notifier_block xenstore_notifier = {
125 .notifier_call = balloon_init_watcher,
126};
127
128void xen_balloon_init(void)
129{
130 register_balloon(&balloon_dev);
131
132 register_xen_selfballooning(&balloon_dev);
133
134 register_xenstore_notifier(&xenstore_notifier);
135}
136EXPORT_SYMBOL_GPL(xen_balloon_init);
137
138#define BALLOON_SHOW(name, format, args...) \
139 static ssize_t show_##name(struct device *dev, \
140 struct device_attribute *attr, \
141 char *buf) \
142 { \
143 return sprintf(buf, format, ##args); \
144 } \
145 static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
146
147BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages));
148BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low));
149BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high));
150
151static DEVICE_ULONG_ATTR(schedule_delay, 0444, balloon_stats.schedule_delay);
152static DEVICE_ULONG_ATTR(max_schedule_delay, 0644, balloon_stats.max_schedule_delay);
153static DEVICE_ULONG_ATTR(retry_count, 0444, balloon_stats.retry_count);
154static DEVICE_ULONG_ATTR(max_retry_count, 0644, balloon_stats.max_retry_count);
155static DEVICE_BOOL_ATTR(scrub_pages, 0644, xen_scrub_pages);
156
157static ssize_t show_target_kb(struct device *dev, struct device_attribute *attr,
158 char *buf)
159{
160 return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages));
161}
162
163static ssize_t store_target_kb(struct device *dev,
164 struct device_attribute *attr,
165 const char *buf,
166 size_t count)
167{
168 char *endchar;
169 unsigned long long target_bytes;
170
171 if (!capable(CAP_SYS_ADMIN))
172 return -EPERM;
173
174 target_bytes = simple_strtoull(buf, &endchar, 0) * 1024;
175
176 balloon_set_new_target(target_bytes >> PAGE_SHIFT);
177
178 return count;
179}
180
181static DEVICE_ATTR(target_kb, S_IRUGO | S_IWUSR,
182 show_target_kb, store_target_kb);
183
184
185static ssize_t show_target(struct device *dev, struct device_attribute *attr,
186 char *buf)
187{
188 return sprintf(buf, "%llu\n",
189 (unsigned long long)balloon_stats.target_pages
190 << PAGE_SHIFT);
191}
192
193static ssize_t store_target(struct device *dev,
194 struct device_attribute *attr,
195 const char *buf,
196 size_t count)
197{
198 char *endchar;
199 unsigned long long target_bytes;
200
201 if (!capable(CAP_SYS_ADMIN))
202 return -EPERM;
203
204 target_bytes = memparse(buf, &endchar);
205
206 balloon_set_new_target(target_bytes >> PAGE_SHIFT);
207
208 return count;
209}
210
211static DEVICE_ATTR(target, S_IRUGO | S_IWUSR,
212 show_target, store_target);
213
214
215static struct attribute *balloon_attrs[] = {
216 &dev_attr_target_kb.attr,
217 &dev_attr_target.attr,
218 &dev_attr_schedule_delay.attr.attr,
219 &dev_attr_max_schedule_delay.attr.attr,
220 &dev_attr_retry_count.attr.attr,
221 &dev_attr_max_retry_count.attr.attr,
222 &dev_attr_scrub_pages.attr.attr,
223 NULL
224};
225
226static const struct attribute_group balloon_group = {
227 .attrs = balloon_attrs
228};
229
230static struct attribute *balloon_info_attrs[] = {
231 &dev_attr_current_kb.attr,
232 &dev_attr_low_kb.attr,
233 &dev_attr_high_kb.attr,
234 NULL
235};
236
237static const struct attribute_group balloon_info_group = {
238 .name = "info",
239 .attrs = balloon_info_attrs
240};
241
242static const struct attribute_group *balloon_groups[] = {
243 &balloon_group,
244 &balloon_info_group,
245 NULL
246};
247
248static struct bus_type balloon_subsys = {
249 .name = BALLOON_CLASS_NAME,
250 .dev_name = BALLOON_CLASS_NAME,
251};
252
253static int register_balloon(struct device *dev)
254{
255 int error;
256
257 error = subsys_system_register(&balloon_subsys, NULL);
258 if (error)
259 return error;
260
261 dev->id = 0;
262 dev->bus = &balloon_subsys;
263 dev->groups = balloon_groups;
264
265 error = device_register(dev);
266 if (error) {
267 bus_unregister(&balloon_subsys);
268 return error;
269 }
270
271 return 0;
272}
273