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[mirror_ubuntu-hirsute-kernel.git] / drivers / xen / xen-balloon.c
CommitLineData
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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
283c0972
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33#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
34
803eb047 35#include <linux/kernel.h>
106eaa8e
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36#include <linux/errno.h>
37#include <linux/mm_types.h>
38#include <linux/init.h>
803eb047 39#include <linux/capability.h>
1d988ed4 40#include <linux/memory_hotplug.h>
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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>
197ecb38 48#include <xen/mem-reservation.h>
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49
50#define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10))
51
52#define BALLOON_CLASS_NAME "xen_memory"
53
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54#ifdef CONFIG_MEMORY_HOTPLUG
55u64 xen_saved_max_mem_size = 0;
56#endif
57
07068021 58static struct device balloon_dev;
803eb047 59
07068021 60static int register_balloon(struct device *dev);
803eb047 61
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62/* React to a change in the target key */
63static void watch_target(struct xenbus_watch *watch,
5584ea25 64 const char *path, const char *token)
803eb047 65{
5266b8e4 66 unsigned long long new_target, static_max;
803eb047 67 int err;
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68 static bool watch_fired;
69 static long target_diff;
803eb047 70
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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
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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 */
96edd61d 86 new_target >>= PAGE_SHIFT - 10;
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87
88 if (!watch_fired) {
89 watch_fired = true;
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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))
5266b8e4 95 static_max >>= PAGE_SHIFT - 10;
3aa6c19d 96 else
eda4eabf 97 static_max = balloon_stats.current_pages;
3aa6c19d 98
3596924a 99 target_diff = (xen_pv_domain() || xen_initial_domain()) ? 0
5266b8e4 100 : static_max - balloon_stats.target_pages;
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101 }
102
5266b8e4 103 balloon_set_new_target(new_target - target_diff);
803eb047 104}
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105static struct xenbus_watch target_watch = {
106 .node = "memory/target",
107 .callback = watch_target,
108};
109
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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)
283c0972 119 pr_err("Failed to set balloon watcher\n");
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120
121 return NOTIFY_DONE;
122}
123
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124static struct notifier_block xenstore_notifier = {
125 .notifier_call = balloon_init_watcher,
126};
803eb047 127
96edd61d 128void xen_balloon_init(void)
803eb047 129{
07068021 130 register_balloon(&balloon_dev);
803eb047 131
803eb047 132 register_xenstore_notifier(&xenstore_notifier);
803eb047 133}
96edd61d 134EXPORT_SYMBOL_GPL(xen_balloon_init);
803eb047 135
803eb047 136#define BALLOON_SHOW(name, format, args...) \
07068021
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137 static ssize_t show_##name(struct device *dev, \
138 struct device_attribute *attr, \
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139 char *buf) \
140 { \
141 return sprintf(buf, format, ##args); \
142 } \
07068021 143 static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
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144
145BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages));
146BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low));
147BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high));
148
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149static DEVICE_ULONG_ATTR(schedule_delay, 0444, balloon_stats.schedule_delay);
150static DEVICE_ULONG_ATTR(max_schedule_delay, 0644, balloon_stats.max_schedule_delay);
151static DEVICE_ULONG_ATTR(retry_count, 0444, balloon_stats.retry_count);
152static DEVICE_ULONG_ATTR(max_retry_count, 0644, balloon_stats.max_retry_count);
197ecb38 153static DEVICE_BOOL_ATTR(scrub_pages, 0644, xen_scrub_pages);
803eb047 154
07068021 155static ssize_t show_target_kb(struct device *dev, struct device_attribute *attr,
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156 char *buf)
157{
158 return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages));
159}
160
07068021
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161static ssize_t store_target_kb(struct device *dev,
162 struct device_attribute *attr,
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163 const char *buf,
164 size_t count)
165{
166 char *endchar;
167 unsigned long long target_bytes;
168
169 if (!capable(CAP_SYS_ADMIN))
170 return -EPERM;
171
172 target_bytes = simple_strtoull(buf, &endchar, 0) * 1024;
173
174 balloon_set_new_target(target_bytes >> PAGE_SHIFT);
175
176 return count;
177}
178
07068021 179static DEVICE_ATTR(target_kb, S_IRUGO | S_IWUSR,
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180 show_target_kb, store_target_kb);
181
182
07068021 183static ssize_t show_target(struct device *dev, struct device_attribute *attr,
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184 char *buf)
185{
186 return sprintf(buf, "%llu\n",
187 (unsigned long long)balloon_stats.target_pages
188 << PAGE_SHIFT);
189}
190
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191static ssize_t store_target(struct device *dev,
192 struct device_attribute *attr,
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193 const char *buf,
194 size_t count)
195{
196 char *endchar;
197 unsigned long long target_bytes;
198
199 if (!capable(CAP_SYS_ADMIN))
200 return -EPERM;
201
202 target_bytes = memparse(buf, &endchar);
203
204 balloon_set_new_target(target_bytes >> PAGE_SHIFT);
205
206 return count;
207}
208
07068021 209static DEVICE_ATTR(target, S_IRUGO | S_IWUSR,
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210 show_target, store_target);
211
212
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213static struct attribute *balloon_attrs[] = {
214 &dev_attr_target_kb.attr,
215 &dev_attr_target.attr,
216 &dev_attr_schedule_delay.attr.attr,
217 &dev_attr_max_schedule_delay.attr.attr,
218 &dev_attr_retry_count.attr.attr,
219 &dev_attr_max_retry_count.attr.attr,
197ecb38 220 &dev_attr_scrub_pages.attr.attr,
b6a473a7
TI
221 NULL
222};
223
224static const struct attribute_group balloon_group = {
225 .attrs = balloon_attrs
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226};
227
228static struct attribute *balloon_info_attrs[] = {
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229 &dev_attr_current_kb.attr,
230 &dev_attr_low_kb.attr,
231 &dev_attr_high_kb.attr,
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232 NULL
233};
234
ead1d014 235static const struct attribute_group balloon_info_group = {
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236 .name = "info",
237 .attrs = balloon_info_attrs
238};
239
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240static const struct attribute_group *balloon_groups[] = {
241 &balloon_group,
242 &balloon_info_group,
243 NULL
244};
245
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246static struct bus_type balloon_subsys = {
247 .name = BALLOON_CLASS_NAME,
248 .dev_name = BALLOON_CLASS_NAME,
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249};
250
07068021 251static int register_balloon(struct device *dev)
803eb047 252{
b6a473a7 253 int error;
803eb047 254
8ea11f7f 255 error = subsys_system_register(&balloon_subsys, NULL);
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256 if (error)
257 return error;
258
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259 dev->id = 0;
260 dev->bus = &balloon_subsys;
b6a473a7 261 dev->groups = balloon_groups;
803eb047 262
07068021 263 error = device_register(dev);
803eb047 264 if (error) {
07068021 265 bus_unregister(&balloon_subsys);
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266 return error;
267 }
268
803eb047 269 return 0;
803eb047 270}