linux/drivers/xen/xen-balloon.c
<<
>>
Prefs
   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#include <linux/kernel.h>
  34#include <linux/module.h>
  35#include <linux/capability.h>
  36
  37#include <xen/xen.h>
  38#include <xen/interface/xen.h>
  39#include <xen/balloon.h>
  40#include <xen/xenbus.h>
  41#include <xen/features.h>
  42#include <xen/page.h>
  43
  44#define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10))
  45
  46#define BALLOON_CLASS_NAME "xen_memory"
  47
  48static struct device balloon_dev;
  49
  50static int register_balloon(struct device *dev);
  51
  52/* React to a change in the target key */
  53static void watch_target(struct xenbus_watch *watch,
  54                         const char **vec, unsigned int len)
  55{
  56        unsigned long long new_target;
  57        int err;
  58
  59        err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target);
  60        if (err != 1) {
  61                /* This is ok (for domain0 at least) - so just return */
  62                return;
  63        }
  64
  65        /* The given memory/target value is in KiB, so it needs converting to
  66         * pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10.
  67         */
  68        balloon_set_new_target(new_target >> (PAGE_SHIFT - 10));
  69}
  70static struct xenbus_watch target_watch = {
  71        .node = "memory/target",
  72        .callback = watch_target,
  73};
  74
  75
  76static int balloon_init_watcher(struct notifier_block *notifier,
  77                                unsigned long event,
  78                                void *data)
  79{
  80        int err;
  81
  82        err = register_xenbus_watch(&target_watch);
  83        if (err)
  84                printk(KERN_ERR "Failed to set balloon watcher\n");
  85
  86        return NOTIFY_DONE;
  87}
  88
  89static struct notifier_block xenstore_notifier = {
  90        .notifier_call = balloon_init_watcher,
  91};
  92
  93static int __init balloon_init(void)
  94{
  95        if (!xen_domain())
  96                return -ENODEV;
  97
  98        pr_info("xen-balloon: Initialising balloon driver.\n");
  99
 100        register_balloon(&balloon_dev);
 101
 102        register_xen_selfballooning(&balloon_dev);
 103
 104        register_xenstore_notifier(&xenstore_notifier);
 105
 106        return 0;
 107}
 108subsys_initcall(balloon_init);
 109
 110static void balloon_exit(void)
 111{
 112    /* XXX - release balloon here */
 113    return;
 114}
 115
 116module_exit(balloon_exit);
 117
 118#define BALLOON_SHOW(name, format, args...)                             \
 119        static ssize_t show_##name(struct device *dev,                  \
 120                                   struct device_attribute *attr,       \
 121                                   char *buf)                           \
 122        {                                                               \
 123                return sprintf(buf, format, ##args);                    \
 124        }                                                               \
 125        static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
 126
 127BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages));
 128BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low));
 129BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high));
 130
 131static DEVICE_ULONG_ATTR(schedule_delay, 0444, balloon_stats.schedule_delay);
 132static DEVICE_ULONG_ATTR(max_schedule_delay, 0644, balloon_stats.max_schedule_delay);
 133static DEVICE_ULONG_ATTR(retry_count, 0444, balloon_stats.retry_count);
 134static DEVICE_ULONG_ATTR(max_retry_count, 0644, balloon_stats.max_retry_count);
 135
 136static ssize_t show_target_kb(struct device *dev, struct device_attribute *attr,
 137                              char *buf)
 138{
 139        return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages));
 140}
 141
 142static ssize_t store_target_kb(struct device *dev,
 143                               struct device_attribute *attr,
 144                               const char *buf,
 145                               size_t count)
 146{
 147        char *endchar;
 148        unsigned long long target_bytes;
 149
 150        if (!capable(CAP_SYS_ADMIN))
 151                return -EPERM;
 152
 153        target_bytes = simple_strtoull(buf, &endchar, 0) * 1024;
 154
 155        balloon_set_new_target(target_bytes >> PAGE_SHIFT);
 156
 157        return count;
 158}
 159
 160static DEVICE_ATTR(target_kb, S_IRUGO | S_IWUSR,
 161                   show_target_kb, store_target_kb);
 162
 163
 164static ssize_t show_target(struct device *dev, struct device_attribute *attr,
 165                              char *buf)
 166{
 167        return sprintf(buf, "%llu\n",
 168                       (unsigned long long)balloon_stats.target_pages
 169                       << PAGE_SHIFT);
 170}
 171
 172static ssize_t store_target(struct device *dev,
 173                            struct device_attribute *attr,
 174                            const char *buf,
 175                            size_t count)
 176{
 177        char *endchar;
 178        unsigned long long target_bytes;
 179
 180        if (!capable(CAP_SYS_ADMIN))
 181                return -EPERM;
 182
 183        target_bytes = memparse(buf, &endchar);
 184
 185        balloon_set_new_target(target_bytes >> PAGE_SHIFT);
 186
 187        return count;
 188}
 189
 190static DEVICE_ATTR(target, S_IRUGO | S_IWUSR,
 191                   show_target, store_target);
 192
 193
 194static struct device_attribute *balloon_attrs[] = {
 195        &dev_attr_target_kb,
 196        &dev_attr_target,
 197        &dev_attr_schedule_delay.attr,
 198        &dev_attr_max_schedule_delay.attr,
 199        &dev_attr_retry_count.attr,
 200        &dev_attr_max_retry_count.attr
 201};
 202
 203static struct attribute *balloon_info_attrs[] = {
 204        &dev_attr_current_kb.attr,
 205        &dev_attr_low_kb.attr,
 206        &dev_attr_high_kb.attr,
 207        NULL
 208};
 209
 210static const struct attribute_group balloon_info_group = {
 211        .name = "info",
 212        .attrs = balloon_info_attrs
 213};
 214
 215static struct bus_type balloon_subsys = {
 216        .name = BALLOON_CLASS_NAME,
 217        .dev_name = BALLOON_CLASS_NAME,
 218};
 219
 220static int register_balloon(struct device *dev)
 221{
 222        int i, error;
 223
 224        error = subsys_system_register(&balloon_subsys, NULL);
 225        if (error)
 226                return error;
 227
 228        dev->id = 0;
 229        dev->bus = &balloon_subsys;
 230
 231        error = device_register(dev);
 232        if (error) {
 233                bus_unregister(&balloon_subsys);
 234                return error;
 235        }
 236
 237        for (i = 0; i < ARRAY_SIZE(balloon_attrs); i++) {
 238                error = device_create_file(dev, balloon_attrs[i]);
 239                if (error)
 240                        goto fail;
 241        }
 242
 243        error = sysfs_create_group(&dev->kobj, &balloon_info_group);
 244        if (error)
 245                goto fail;
 246
 247        return 0;
 248
 249 fail:
 250        while (--i >= 0)
 251                device_remove_file(dev, balloon_attrs[i]);
 252        device_unregister(dev);
 253        bus_unregister(&balloon_subsys);
 254        return error;
 255}
 256
 257MODULE_LICENSE("GPL");
 258
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.