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