1 files changed, 264 insertions, 0 deletions
diff --git a/drivers/xen/xen-balloon.c b/drivers/xen/xen-balloon.c
new file mode 100644
index 0000000000..8cd583db20
--- /dev/null
+++ b/drivers/xen/xen-balloon.c
@@ -0,0 +1,264 @@
+/******************************************************************************
+ * 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 = balloon_stats.current_pages;
+
+		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 name##_show(struct device *dev,			\
+				   struct device_attribute *attr,	\
+				   char *buf)				\
+	{								\
+		return sprintf(buf, format, ##args);			\
+	}								\
+	static DEVICE_ATTR_RO(name)
+
+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 target_kb_show(struct device *dev, struct device_attribute *attr,
+			      char *buf)
+{
+	return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages));
+}
+
+static ssize_t target_kb_store(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_RW(target_kb);
+
+static ssize_t target_show(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 target_store(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_RW(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;
+}