265 lines · c
1/******************************************************************************2 * Xen balloon driver - enables returning/claiming memory to/from Xen.3 *4 * Copyright (c) 2003, B Dragovic5 * Copyright (c) 2003-2004, M Williamson, K Fraser6 * Copyright (c) 2005 Dan M. Smith, IBM Corporation7 *8 * This program is free software; you can redistribute it and/or9 * modify it under the terms of the GNU General Public License version 210 * as published by the Free Software Foundation; or, when distributed11 * separately from the Linux kernel or incorporated into other12 * software packages, subject to the following license:13 *14 * Permission is hereby granted, free of charge, to any person obtaining a copy15 * of this source file (the "Software"), to deal in the Software without16 * 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 to19 * the following conditions:20 *21 * The above copyright notice and this permission notice shall be included in22 * all copies or substantial portions of the Software.23 *24 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR25 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,26 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE27 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER28 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING29 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS30 * IN THE SOFTWARE.31 */32 33#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt34 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_HOTPLUG55u64 xen_saved_max_mem_size = 0;56#endif57 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_HOTPLUG72 /* 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#endif76 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 to84 * 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 else97 static_max = balloon_stats.current_pages;98 99 target_diff = (xen_pv_domain() || xen_initial_domain()) ? 0100 : 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_xenstore_notifier(&xenstore_notifier);133}134EXPORT_SYMBOL_GPL(xen_balloon_init);135 136#define BALLOON_SHOW(name, format, args...) \137 static ssize_t name##_show(struct device *dev, \138 struct device_attribute *attr, \139 char *buf) \140 { \141 return sprintf(buf, format, ##args); \142 } \143 static DEVICE_ATTR_RO(name)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 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);153static DEVICE_BOOL_ATTR(scrub_pages, 0644, xen_scrub_pages);154 155static ssize_t target_kb_show(struct device *dev, struct device_attribute *attr,156 char *buf)157{158 return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages));159}160 161static ssize_t target_kb_store(struct device *dev,162 struct device_attribute *attr,163 const char *buf, size_t count)164{165 char *endchar;166 unsigned long long target_bytes;167 168 if (!capable(CAP_SYS_ADMIN))169 return -EPERM;170 171 target_bytes = simple_strtoull(buf, &endchar, 0) * 1024;172 173 balloon_set_new_target(target_bytes >> PAGE_SHIFT);174 175 return count;176}177 178static DEVICE_ATTR_RW(target_kb);179 180static ssize_t target_show(struct device *dev, struct device_attribute *attr,181 char *buf)182{183 return sprintf(buf, "%llu\n",184 (unsigned long long)balloon_stats.target_pages185 << PAGE_SHIFT);186}187 188static ssize_t target_store(struct device *dev,189 struct device_attribute *attr,190 const char *buf, size_t count)191{192 char *endchar;193 unsigned long long target_bytes;194 195 if (!capable(CAP_SYS_ADMIN))196 return -EPERM;197 198 target_bytes = memparse(buf, &endchar);199 200 balloon_set_new_target(target_bytes >> PAGE_SHIFT);201 202 return count;203}204 205static DEVICE_ATTR_RW(target);206 207static struct attribute *balloon_attrs[] = {208 &dev_attr_target_kb.attr,209 &dev_attr_target.attr,210 &dev_attr_schedule_delay.attr.attr,211 &dev_attr_max_schedule_delay.attr.attr,212 &dev_attr_retry_count.attr.attr,213 &dev_attr_max_retry_count.attr.attr,214 &dev_attr_scrub_pages.attr.attr,215 NULL216};217 218static const struct attribute_group balloon_group = {219 .attrs = balloon_attrs220};221 222static struct attribute *balloon_info_attrs[] = {223 &dev_attr_current_kb.attr,224 &dev_attr_low_kb.attr,225 &dev_attr_high_kb.attr,226 NULL227};228 229static const struct attribute_group balloon_info_group = {230 .name = "info",231 .attrs = balloon_info_attrs232};233 234static const struct attribute_group *balloon_groups[] = {235 &balloon_group,236 &balloon_info_group,237 NULL238};239 240static const struct bus_type balloon_subsys = {241 .name = BALLOON_CLASS_NAME,242 .dev_name = BALLOON_CLASS_NAME,243};244 245static int register_balloon(struct device *dev)246{247 int error;248 249 error = subsys_system_register(&balloon_subsys, NULL);250 if (error)251 return error;252 253 dev->id = 0;254 dev->bus = &balloon_subsys;255 dev->groups = balloon_groups;256 257 error = device_register(dev);258 if (error) {259 bus_unregister(&balloon_subsys);260 return error;261 }262 263 return 0;264}265