drivers/xen/xen-balloon.c - linux - Git at Google

 /******************************************************************************
  * Xen balloon driver - enables returning/claiming memory to/from Xen.
  *
  * Copyright (c) 2003, B Dragovic
  * Copyright (c) 2003-2004, M Williamson, K Fraser
  * Copyright (c) 2005 Dan M. Smith, IBM Corporation
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License version 2
  * as published by the Free Software Foundation; or, when distributed
  * separately from the Linux kernel or incorporated into other
  * software packages, subject to the following license:
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this source file (the "Software"), to deal in the Software without
  * restriction, including without limitation the rights to use, copy, modify,
  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  * and to permit persons to whom the Software is furnished to do so, subject to
  * the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  * IN THE SOFTWARE.
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/mm_types.h>
 #include <linux/init.h>
 #include <linux/capability.h>
 #include <linux/memory_hotplug.h>

 #include <xen/xen.h>
 #include <xen/interface/xen.h>
 #include <xen/balloon.h>
 #include <xen/xenbus.h>
 #include <xen/features.h>
 #include <xen/page.h>
 #include <xen/mem-reservation.h>

 #define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10))

 #define BALLOON_CLASS_NAME "xen_memory"

 #ifdef CONFIG_MEMORY_HOTPLUG
 u64 xen_saved_max_mem_size = 0;
 #endif

 static struct device balloon_dev;

 static int register_balloon(struct device *dev);

 /* React to a change in the target key */
 static void watch_target(struct xenbus_watch *watch,
 			 const char *path, const char *token)
 {
 	unsigned long long new_target, static_max;
 	int err;
 	static bool watch_fired;
 	static long target_diff;

 #ifdef CONFIG_MEMORY_HOTPLUG
 	/* The balloon driver will take care of adding memory now. */
 	if (xen_saved_max_mem_size)
 		max_mem_size = xen_saved_max_mem_size;
 #endif

 	err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target);
 	if (err != 1) {
 		/* This is ok (for domain0 at least) - so just return */
 		return;
 	}

 	/* The given memory/target value is in KiB, so it needs converting to
 	 * pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10.
 	 */
 	new_target >>= PAGE_SHIFT - 10;

 	if (!watch_fired) {
 		watch_fired = true;

 		if ((xenbus_scanf(XBT_NIL, "memory", "static-max",
 				  "%llu", &static_max) == 1) ||
 		    (xenbus_scanf(XBT_NIL, "memory", "memory_static_max",
 				  "%llu", &static_max) == 1))
 			static_max >>= PAGE_SHIFT - 10;
 		else
 			static_max = new_target;

 		target_diff = (xen_pv_domain() || xen_initial_domain()) ? 0
 				: static_max - balloon_stats.target_pages;
 	}

 	balloon_set_new_target(new_target - target_diff);
 }
 static struct xenbus_watch target_watch = {
 	.node = "memory/target",
 	.callback = watch_target,
 };


 static int balloon_init_watcher(struct notifier_block *notifier,
 				unsigned long event,
 				void *data)
 {
 	int err;

 	err = register_xenbus_watch(&target_watch);
 	if (err)
 		pr_err("Failed to set balloon watcher\n");

 	return NOTIFY_DONE;
 }

 static struct notifier_block xenstore_notifier = {
 	.notifier_call = balloon_init_watcher,
 };

 void xen_balloon_init(void)
 {
 	register_balloon(&balloon_dev);

 	register_xenstore_notifier(&xenstore_notifier);
 }
 EXPORT_SYMBOL_GPL(xen_balloon_init);

 #define BALLOON_SHOW(name, format, args...)				\
 	static ssize_t show_##name(struct device *dev,			\
 				   struct device_attribute *attr,	\
 				   char *buf)				\
 	{								\
 		return sprintf(buf, format, ##args);			\
 	}								\
 	static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)

 BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages));
 BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low));
 BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high));

 static DEVICE_ULONG_ATTR(schedule_delay, 0444, balloon_stats.schedule_delay);
 static DEVICE_ULONG_ATTR(max_schedule_delay, 0644, balloon_stats.max_schedule_delay);
 static DEVICE_ULONG_ATTR(retry_count, 0444, balloon_stats.retry_count);
 static DEVICE_ULONG_ATTR(max_retry_count, 0644, balloon_stats.max_retry_count);
 static DEVICE_BOOL_ATTR(scrub_pages, 0644, xen_scrub_pages);

 static ssize_t show_target_kb(struct device *dev, struct device_attribute *attr,
 			      char *buf)
 {
 	return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages));
 }

 static ssize_t store_target_kb(struct device *dev,
 			       struct device_attribute *attr,
 			       const char *buf,
 			       size_t count)
 {
 	char *endchar;
 	unsigned long long target_bytes;

 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;

 	target_bytes = simple_strtoull(buf, &endchar, 0) * 1024;

 	balloon_set_new_target(target_bytes >> PAGE_SHIFT);

 	return count;
 }

 static DEVICE_ATTR(target_kb, S_IRUGO | S_IWUSR,
 		   show_target_kb, store_target_kb);


 static ssize_t show_target(struct device *dev, struct device_attribute *attr,
 			      char *buf)
 {
 	return sprintf(buf, "%llu\n",
 		       (unsigned long long)balloon_stats.target_pages
 		       << PAGE_SHIFT);
 }

 static ssize_t store_target(struct device *dev,
 			    struct device_attribute *attr,
 			    const char *buf,
 			    size_t count)
 {
 	char *endchar;
 	unsigned long long target_bytes;

 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;

 	target_bytes = memparse(buf, &endchar);

 	balloon_set_new_target(target_bytes >> PAGE_SHIFT);

 	return count;
 }

 static DEVICE_ATTR(target, S_IRUGO | S_IWUSR,
 		   show_target, store_target);


 static struct attribute *balloon_attrs[] = {
 	&dev_attr_target_kb.attr,
 	&dev_attr_target.attr,
 	&dev_attr_schedule_delay.attr.attr,
 	&dev_attr_max_schedule_delay.attr.attr,
 	&dev_attr_retry_count.attr.attr,
 	&dev_attr_max_retry_count.attr.attr,
 	&dev_attr_scrub_pages.attr.attr,
 	NULL
 };

 static const struct attribute_group balloon_group = {
 	.attrs = balloon_attrs
 };

 static struct attribute *balloon_info_attrs[] = {
 	&dev_attr_current_kb.attr,
 	&dev_attr_low_kb.attr,
 	&dev_attr_high_kb.attr,
 	NULL
 };

 static const struct attribute_group balloon_info_group = {
 	.name = "info",
 	.attrs = balloon_info_attrs
 };

 static const struct attribute_group *balloon_groups[] = {
 	&balloon_group,
 	&balloon_info_group,
 	NULL
 };

 static struct bus_type balloon_subsys = {
 	.name = BALLOON_CLASS_NAME,
 	.dev_name = BALLOON_CLASS_NAME,
 };

 static int register_balloon(struct device *dev)
 {
 	int error;

 	error = subsys_system_register(&balloon_subsys, NULL);
 	if (error)
 		return error;

 	dev->id = 0;
 	dev->bus = &balloon_subsys;
 	dev->groups = balloon_groups;

 	error = device_register(dev);
 	if (error) {
 		bus_unregister(&balloon_subsys);
 		return error;
 	}

 	return 0;
 }
	/******************************************************************************
	* Xen balloon driver - enables returning/claiming memory to/from Xen.
	*
	* Copyright (c) 2003, B Dragovic
	* Copyright (c) 2003-2004, M Williamson, K Fraser
	* Copyright (c) 2005 Dan M. Smith, IBM Corporation
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License version 2
	* as published by the Free Software Foundation; or, when distributed
	* separately from the Linux kernel or incorporated into other
	* software packages, subject to the following license:
	*
	* Permission is hereby granted, free of charge, to any person obtaining a copy
	* of this source file (the "Software"), to deal in the Software without
	* restriction, including without limitation the rights to use, copy, modify,
	* merge, publish, distribute, sublicense, and/or sell copies of the Software,
	* and to permit persons to whom the Software is furnished to do so, subject to
	* the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
	* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
	* IN THE SOFTWARE.
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/kernel.h>
	#include <linux/errno.h>
	#include <linux/mm_types.h>
	#include <linux/init.h>
	#include <linux/capability.h>
	#include <linux/memory_hotplug.h>

	#include <xen/xen.h>
	#include <xen/interface/xen.h>
	#include <xen/balloon.h>
	#include <xen/xenbus.h>
	#include <xen/features.h>
	#include <xen/page.h>
	#include <xen/mem-reservation.h>

	#define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10))

	#define BALLOON_CLASS_NAME "xen_memory"

	#ifdef CONFIG_MEMORY_HOTPLUG
	u64 xen_saved_max_mem_size = 0;
	#endif

	static struct device balloon_dev;

	static int register_balloon(struct device *dev);

	/* React to a change in the target key */
	static void watch_target(struct xenbus_watch *watch,
	const char path, const char token)
	{
	unsigned long long new_target, static_max;
	int err;
	static bool watch_fired;
	static long target_diff;

	#ifdef CONFIG_MEMORY_HOTPLUG
	/* The balloon driver will take care of adding memory now. */
	if (xen_saved_max_mem_size)
	max_mem_size = xen_saved_max_mem_size;
	#endif

	err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target);
	if (err != 1) {
	/* This is ok (for domain0 at least) - so just return */
	return;
	}

	/* The given memory/target value is in KiB, so it needs converting to
	* pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10.
	*/
	new_target >>= PAGE_SHIFT - 10;

	if (!watch_fired) {
	watch_fired = true;

	if ((xenbus_scanf(XBT_NIL, "memory", "static-max",
	"%llu", &static_max) == 1) \|\|
	(xenbus_scanf(XBT_NIL, "memory", "memory_static_max",
	"%llu", &static_max) == 1))
	static_max >>= PAGE_SHIFT - 10;
	else
	static_max = new_target;

	target_diff = (xen_pv_domain() \|\| xen_initial_domain()) ? 0
	: static_max - balloon_stats.target_pages;
	}

	balloon_set_new_target(new_target - target_diff);
	}
	static struct xenbus_watch target_watch = {
	.node = "memory/target",
	.callback = watch_target,
	};


	static int balloon_init_watcher(struct notifier_block *notifier,
	unsigned long event,
	void *data)
	{
	int err;

	err = register_xenbus_watch(&target_watch);
	if (err)
	pr_err("Failed to set balloon watcher\n");

	return NOTIFY_DONE;
	}

	static struct notifier_block xenstore_notifier = {
	.notifier_call = balloon_init_watcher,
	};

	void xen_balloon_init(void)
	{
	register_balloon(&balloon_dev);

	register_xenstore_notifier(&xenstore_notifier);
	}
	EXPORT_SYMBOL_GPL(xen_balloon_init);

	#define BALLOON_SHOW(name, format, args...) \
	static ssize_t show_##name(struct device *dev, \
	struct device_attribute *attr, \
	char *buf) \
	{ \
	return sprintf(buf, format, ##args); \
	} \
	static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)

	BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages));
	BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low));
	BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high));

	static DEVICE_ULONG_ATTR(schedule_delay, 0444, balloon_stats.schedule_delay);
	static DEVICE_ULONG_ATTR(max_schedule_delay, 0644, balloon_stats.max_schedule_delay);
	static DEVICE_ULONG_ATTR(retry_count, 0444, balloon_stats.retry_count);
	static DEVICE_ULONG_ATTR(max_retry_count, 0644, balloon_stats.max_retry_count);
	static DEVICE_BOOL_ATTR(scrub_pages, 0644, xen_scrub_pages);

	static ssize_t show_target_kb(struct device dev, struct device_attribute attr,
	char *buf)
	{
	return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages));
	}

	static ssize_t store_target_kb(struct device *dev,
	struct device_attribute *attr,
	const char *buf,
	size_t count)
	{
	char *endchar;
	unsigned long long target_bytes;

	if (!capable(CAP_SYS_ADMIN))
	return -EPERM;

	target_bytes = simple_strtoull(buf, &endchar, 0) * 1024;

	balloon_set_new_target(target_bytes >> PAGE_SHIFT);

	return count;
	}

	static DEVICE_ATTR(target_kb, S_IRUGO \| S_IWUSR,
	show_target_kb, store_target_kb);


	static ssize_t show_target(struct device dev, struct device_attribute attr,
	char *buf)
	{
	return sprintf(buf, "%llu\n",
	(unsigned long long)balloon_stats.target_pages
	<< PAGE_SHIFT);
	}

	static ssize_t store_target(struct device *dev,
	struct device_attribute *attr,
	const char *buf,
	size_t count)
	{
	char *endchar;
	unsigned long long target_bytes;

	if (!capable(CAP_SYS_ADMIN))
	return -EPERM;

	target_bytes = memparse(buf, &endchar);

	balloon_set_new_target(target_bytes >> PAGE_SHIFT);

	return count;
	}

	static DEVICE_ATTR(target, S_IRUGO \| S_IWUSR,
	show_target, store_target);


	static struct attribute *balloon_attrs[] = {
	&dev_attr_target_kb.attr,
	&dev_attr_target.attr,
	&dev_attr_schedule_delay.attr.attr,
	&dev_attr_max_schedule_delay.attr.attr,
	&dev_attr_retry_count.attr.attr,
	&dev_attr_max_retry_count.attr.attr,
	&dev_attr_scrub_pages.attr.attr,
	NULL
	};

	static const struct attribute_group balloon_group = {
	.attrs = balloon_attrs
	};

	static struct attribute *balloon_info_attrs[] = {
	&dev_attr_current_kb.attr,
	&dev_attr_low_kb.attr,
	&dev_attr_high_kb.attr,
	NULL
	};

	static const struct attribute_group balloon_info_group = {
	.name = "info",
	.attrs = balloon_info_attrs
	};

	static const struct attribute_group *balloon_groups[] = {
	&balloon_group,
	&balloon_info_group,
	NULL
	};

	static struct bus_type balloon_subsys = {
	.name = BALLOON_CLASS_NAME,
	.dev_name = BALLOON_CLASS_NAME,
	};

	static int register_balloon(struct device *dev)
	{
	int error;

	error = subsys_system_register(&balloon_subsys, NULL);
	if (error)
	return error;

	dev->id = 0;
	dev->bus = &balloon_subsys;
	dev->groups = balloon_groups;

	error = device_register(dev);
	if (error) {
	bus_unregister(&balloon_subsys);
	return error;
	}

	return 0;
	}