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xen-balloon: Move core balloon functionality out of module
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The basic functionality of ballooning pages is useful for Xen drivers in
general. Rather than require a dependency on the balloon module, split
the functionality that is reused into the core. The balloon module is
still required to follow ballooning requests from xenstore or to view
balloon statistics in sysfs.

Acked-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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Daniel De Graaf authored and Konrad Rzeszutek Wilk committed Mar 16, 2011
1 parent 40095de commit 803eb04
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Showing 4 changed files with 286 additions and 225 deletions.
4 changes: 2 additions & 2 deletions drivers/xen/Makefile
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
obj-y += grant-table.o features.o events.o manage.o
obj-y += grant-table.o features.o events.o manage.o balloon.o
obj-y += xenbus/

nostackp := $(call cc-option, -fno-stack-protector)
Expand All @@ -7,7 +7,7 @@ CFLAGS_features.o := $(nostackp)
obj-$(CONFIG_BLOCK) += biomerge.o
obj-$(CONFIG_HOTPLUG_CPU) += cpu_hotplug.o
obj-$(CONFIG_XEN_XENCOMM) += xencomm.o
obj-$(CONFIG_XEN_BALLOON) += balloon.o
obj-$(CONFIG_XEN_BALLOON) += xen-balloon.o
obj-$(CONFIG_XEN_DEV_EVTCHN) += xen-evtchn.o
obj-$(CONFIG_XEN_GNTDEV) += xen-gntdev.o
obj-$(CONFIG_XEN_GRANT_DEV_ALLOC) += xen-gntalloc.o
Expand Down
229 changes: 6 additions & 223 deletions drivers/xen/balloon.c
View file
Original file line number Diff line number Diff line change
@@ -1,6 +1,4 @@
/******************************************************************************
* balloon.c
*
* Xen balloon driver - enables returning/claiming memory to/from Xen.
*
* Copyright (c) 2003, B Dragovic
Expand Down Expand Up @@ -33,7 +31,6 @@
*/

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/mm.h>
Expand All @@ -42,13 +39,11 @@
#include <linux/highmem.h>
#include <linux/mutex.h>
#include <linux/list.h>
#include <linux/sysdev.h>
#include <linux/gfp.h>

#include <asm/page.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/uaccess.h>
#include <asm/tlb.h>
#include <asm/e820.h>

Expand All @@ -58,14 +53,10 @@
#include <xen/xen.h>
#include <xen/interface/xen.h>
#include <xen/interface/memory.h>
#include <xen/xenbus.h>
#include <xen/balloon.h>
#include <xen/features.h>
#include <xen/page.h>

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

#define BALLOON_CLASS_NAME "xen_memory"

/*
* balloon_process() state:
*
Expand All @@ -80,28 +71,11 @@ enum bp_state {
BP_ECANCELED
};

#define RETRY_UNLIMITED 0

struct balloon_stats {
/* We aim for 'current allocation' == 'target allocation'. */
unsigned long current_pages;
unsigned long target_pages;
/* Number of pages in high- and low-memory balloons. */
unsigned long balloon_low;
unsigned long balloon_high;
unsigned long schedule_delay;
unsigned long max_schedule_delay;
unsigned long retry_count;
unsigned long max_retry_count;
};

static DEFINE_MUTEX(balloon_mutex);

static struct sys_device balloon_sysdev;

static int register_balloon(struct sys_device *sysdev);

static struct balloon_stats balloon_stats;
struct balloon_stats balloon_stats;
EXPORT_SYMBOL_GPL(balloon_stats);

/* We increase/decrease in batches which fit in a page */
static unsigned long frame_list[PAGE_SIZE / sizeof(unsigned long)];
Expand Down Expand Up @@ -384,51 +358,13 @@ static void balloon_process(struct work_struct *work)
}

/* Resets the Xen limit, sets new target, and kicks off processing. */
static void balloon_set_new_target(unsigned long target)
void balloon_set_new_target(unsigned long target)
{
/* No need for lock. Not read-modify-write updates. */
balloon_stats.target_pages = target;
schedule_delayed_work(&balloon_worker, 0);
}

static struct xenbus_watch target_watch =
{
.node = "memory/target"
};

/* React to a change in the target key */
static void watch_target(struct xenbus_watch *watch,
const char **vec, unsigned int len)
{
unsigned long long new_target;
int err;

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.
*/
balloon_set_new_target(new_target >> (PAGE_SHIFT - 10));
}

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

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

return NOTIFY_DONE;
}

static struct notifier_block xenstore_notifier;
EXPORT_SYMBOL_GPL(balloon_set_new_target);

static int __init balloon_init(void)
{
Expand All @@ -438,7 +374,7 @@ static int __init balloon_init(void)
if (!xen_pv_domain())
return -ENODEV;

pr_info("xen_balloon: Initialising balloon driver.\n");
pr_info("xen/balloon: Initialising balloon driver.\n");

balloon_stats.current_pages = min(xen_start_info->nr_pages, max_pfn);
balloon_stats.target_pages = balloon_stats.current_pages;
Expand All @@ -450,8 +386,6 @@ static int __init balloon_init(void)
balloon_stats.retry_count = 1;
balloon_stats.max_retry_count = RETRY_UNLIMITED;

register_balloon(&balloon_sysdev);

/*
* Initialise the balloon with excess memory space. We need
* to make sure we don't add memory which doesn't exist or
Expand All @@ -472,160 +406,9 @@ static int __init balloon_init(void)
__balloon_append(page);
}

target_watch.callback = watch_target;
xenstore_notifier.notifier_call = balloon_init_watcher;

register_xenstore_notifier(&xenstore_notifier);

return 0;
}

subsys_initcall(balloon_init);

static void balloon_exit(void)
{
/* XXX - release balloon here */
return;
}

module_exit(balloon_exit);

#define BALLOON_SHOW(name, format, args...) \
static ssize_t show_##name(struct sys_device *dev, \
struct sysdev_attribute *attr, \
char *buf) \
{ \
return sprintf(buf, format, ##args); \
} \
static SYSDEV_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 SYSDEV_ULONG_ATTR(schedule_delay, 0444, balloon_stats.schedule_delay);
static SYSDEV_ULONG_ATTR(max_schedule_delay, 0644, balloon_stats.max_schedule_delay);
static SYSDEV_ULONG_ATTR(retry_count, 0444, balloon_stats.retry_count);
static SYSDEV_ULONG_ATTR(max_retry_count, 0644, balloon_stats.max_retry_count);

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

static ssize_t store_target_kb(struct sys_device *dev,
struct sysdev_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 SYSDEV_ATTR(target_kb, S_IRUGO | S_IWUSR,
show_target_kb, store_target_kb);


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

static ssize_t store_target(struct sys_device *dev,
struct sysdev_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 SYSDEV_ATTR(target, S_IRUGO | S_IWUSR,
show_target, store_target);


static struct sysdev_attribute *balloon_attrs[] = {
&attr_target_kb,
&attr_target,
&attr_schedule_delay.attr,
&attr_max_schedule_delay.attr,
&attr_retry_count.attr,
&attr_max_retry_count.attr
};

static struct attribute *balloon_info_attrs[] = {
&attr_current_kb.attr,
&attr_low_kb.attr,
&attr_high_kb.attr,
NULL
};

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

static struct sysdev_class balloon_sysdev_class = {
.name = BALLOON_CLASS_NAME,
};

static int register_balloon(struct sys_device *sysdev)
{
int i, error;

error = sysdev_class_register(&balloon_sysdev_class);
if (error)
return error;

sysdev->id = 0;
sysdev->cls = &balloon_sysdev_class;

error = sysdev_register(sysdev);
if (error) {
sysdev_class_unregister(&balloon_sysdev_class);
return error;
}

for (i = 0; i < ARRAY_SIZE(balloon_attrs); i++) {
error = sysdev_create_file(sysdev, balloon_attrs[i]);
if (error)
goto fail;
}

error = sysfs_create_group(&sysdev->kobj, &balloon_info_group);
if (error)
goto fail;

return 0;

fail:
while (--i >= 0)
sysdev_remove_file(sysdev, balloon_attrs[i]);
sysdev_unregister(sysdev);
sysdev_class_unregister(&balloon_sysdev_class);
return error;
}

MODULE_LICENSE("GPL");
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