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