1 files changed, 161 insertions, 259 deletions

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 500290b150bb..f54290baa3db 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -1,6 +1,4 @@
 /******************************************************************************
- * balloon.c
- *
  * Xen balloon driver - enables returning/claiming memory to/from Xen.
  *
  * Copyright (c) 2003, B Dragovic
@@ -33,7 +31,6 @@
  */
 
 #include <linux/kernel.h>
-#include <linux/module.h>
 #include <linux/sched.h>
 #include <linux/errno.h>
 #include <linux/mm.h>
@@ -42,14 +39,13 @@
 #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>
 
 #include <asm/xen/hypervisor.h>
 #include <asm/xen/hypercall.h>
@@ -57,35 +53,29 @@
 #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:
+ *
+ * BP_DONE: done or nothing to do,
+ * BP_EAGAIN: error, go to sleep,
+ * BP_ECANCELED: error, balloon operation canceled.
+ */
 
-struct balloon_stats {
-        /* We aim for 'current allocation' == 'target allocation'. */
-        unsigned long current_pages;
-        unsigned long target_pages;
-        /*
-         * Drivers may alter the memory reservation independently, but they
-         * must inform the balloon driver so we avoid hitting the hard limit.
-         */
-        unsigned long driver_pages;
-        /* Number of pages in high- and low-memory balloons. */
-        unsigned long balloon_low;
-        unsigned long balloon_high;
+enum bp_state {
+        BP_DONE,
+        BP_EAGAIN,
+        BP_ECANCELED
 };
 
-static DEFINE_MUTEX(balloon_mutex);
-
-static struct sys_device balloon_sysdev;
 
-static int register_balloon(struct sys_device *sysdev);
+static DEFINE_MUTEX(balloon_mutex);
 
-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)];
@@ -103,8 +93,7 @@ static LIST_HEAD(ballooned_pages);
 
 /* Main work function, always executed in process context. */
 static void balloon_process(struct work_struct *work);
-static DECLARE_WORK(balloon_worker, balloon_process);
-static struct timer_list balloon_timer;
+static DECLARE_DELAYED_WORK(balloon_worker, balloon_process);
 
 /* When ballooning out (allocating memory to return to Xen) we don't really
    want the kernel to try too hard since that can trigger the oom killer. */
@@ -119,30 +108,38 @@ static void scrub_page(struct page *page)
 }
 
 /* balloon_append: add the given page to the balloon. */
-static void balloon_append(struct page *page)
+static void __balloon_append(struct page *page)
 {
         /* Lowmem is re-populated first, so highmem pages go at list tail. */
         if (PageHighMem(page)) {
                 list_add_tail(&page->lru, &ballooned_pages);
                 balloon_stats.balloon_high++;
-                dec_totalhigh_pages();
         } else {
                 list_add(&page->lru, &ballooned_pages);
                 balloon_stats.balloon_low++;
         }
+}
 
+static void balloon_append(struct page *page)
+{
+        __balloon_append(page);
+        if (PageHighMem(page))
+                dec_totalhigh_pages();
         totalram_pages--;
 }
 
 /* balloon_retrieve: rescue a page from the balloon, if it is not empty. */
-static struct page *balloon_retrieve(void)
+static struct page *balloon_retrieve(bool prefer_highmem)
 {
         struct page *page;
 
         if (list_empty(&ballooned_pages))
                 return NULL;
 
-        page = list_entry(ballooned_pages.next, struct page, lru);
+        if (prefer_highmem)
+                page = list_entry(ballooned_pages.prev, struct page, lru);
+        else
+                page = list_entry(ballooned_pages.next, struct page, lru);
         list_del(&page->lru);
 
         if (PageHighMem(page)) {
@@ -172,12 +169,32 @@ static struct page *balloon_next_page(struct page *page)
         return list_entry(next, struct page, lru);
 }
 
-static void balloon_alarm(unsigned long unused)
+static enum bp_state update_schedule(enum bp_state state)
 {
-        schedule_work(&balloon_worker);
+        if (state == BP_DONE) {
+                balloon_stats.schedule_delay = 1;
+                balloon_stats.retry_count = 1;
+                return BP_DONE;
+        }
+
+        ++balloon_stats.retry_count;
+
+        if (balloon_stats.max_retry_count != RETRY_UNLIMITED &&
+                        balloon_stats.retry_count > balloon_stats.max_retry_count) {
+                balloon_stats.schedule_delay = 1;
+                balloon_stats.retry_count = 1;
+                return BP_ECANCELED;
+        }
+
+        balloon_stats.schedule_delay <<= 1;
+
+        if (balloon_stats.schedule_delay > balloon_stats.max_schedule_delay)
+                balloon_stats.schedule_delay = balloon_stats.max_schedule_delay;
+
+        return BP_EAGAIN;
 }
 
-static unsigned long current_target(void)
+static long current_credit(void)
 {
         unsigned long target = balloon_stats.target_pages;
 
@@ -186,14 +203,14 @@ static unsigned long current_target(void)
                      balloon_stats.balloon_low +
                      balloon_stats.balloon_high);
 
-        return target;
+        return target - balloon_stats.current_pages;
 }
 
-static int increase_reservation(unsigned long nr_pages)
+static enum bp_state increase_reservation(unsigned long nr_pages)
 {
-        unsigned long  pfn, i, flags;
+        int rc;
+        unsigned long  pfn, i;
         struct page   *page;
-        long           rc;
         struct xen_memory_reservation reservation = {
                 .address_bits = 0,
                 .extent_order = 0,
@@ -203,11 +220,12 @@ static int increase_reservation(unsigned long nr_pages)
         if (nr_pages > ARRAY_SIZE(frame_list))
                 nr_pages = ARRAY_SIZE(frame_list);
 
-        spin_lock_irqsave(&xen_reservation_lock, flags);
-
         page = balloon_first_page();
         for (i = 0; i < nr_pages; i++) {
-                BUG_ON(page == NULL);
+                if (!page) {
+                        nr_pages = i;
+                        break;
+                }
                 frame_list[i] = page_to_pfn(page);
                 page = balloon_next_page(page);
         }
@@ -215,11 +233,11 @@ static int increase_reservation(unsigned long nr_pages)
         set_xen_guest_handle(reservation.extent_start, frame_list);
         reservation.nr_extents = nr_pages;
         rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
-        if (rc < 0)
-                goto out;
+        if (rc <= 0)
+                return BP_EAGAIN;
 
         for (i = 0; i < rc; i++) {
-                page = balloon_retrieve();
+                page = balloon_retrieve(false);
                 BUG_ON(page == NULL);
 
                 pfn = page_to_pfn(page);
@@ -229,7 +247,7 @@ static int increase_reservation(unsigned long nr_pages)
                 set_phys_to_machine(pfn, frame_list[i]);
 
                 /* Link back into the page tables if not highmem. */
-                if (pfn < max_low_pfn) {
+                if (xen_pv_domain() && !PageHighMem(page)) {
                         int ret;
                         ret = HYPERVISOR_update_va_mapping(
                                 (unsigned long)__va(pfn << PAGE_SHIFT),
@@ -246,17 +264,14 @@ static int increase_reservation(unsigned long nr_pages)
 
         balloon_stats.current_pages += rc;
 
- out:
-        spin_unlock_irqrestore(&xen_reservation_lock, flags);
-
-        return rc < 0 ? rc : rc != nr_pages;
+        return BP_DONE;
 }
 
-static int decrease_reservation(unsigned long nr_pages)
+static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
 {
-        unsigned long  pfn, i, flags;
+        enum bp_state state = BP_DONE;
+        unsigned long  pfn, i;
         struct page   *page;
-        int            need_sleep = 0;
         int ret;
         struct xen_memory_reservation reservation = {
                 .address_bits = 0,
@@ -268,9 +283,9 @@ static int decrease_reservation(unsigned long nr_pages)
                 nr_pages = ARRAY_SIZE(frame_list);
 
         for (i = 0; i < nr_pages; i++) {
-                if ((page = alloc_page(GFP_BALLOON)) == NULL) {
+                if ((page = alloc_page(gfp)) == NULL) {
                         nr_pages = i;
-                        need_sleep = 1;
+                        state = BP_EAGAIN;
                         break;
                 }
 
@@ -279,7 +294,7 @@ static int decrease_reservation(unsigned long nr_pages)
 
                 scrub_page(page);
 
-                if (!PageHighMem(page)) {
+                if (xen_pv_domain() && !PageHighMem(page)) {
                         ret = HYPERVISOR_update_va_mapping(
                                 (unsigned long)__va(pfn << PAGE_SHIFT),
                                 __pte_ma(0), 0);
@@ -292,12 +307,10 @@ static int decrease_reservation(unsigned long nr_pages)
         kmap_flush_unused();
         flush_tlb_all();
 
-        spin_lock_irqsave(&xen_reservation_lock, flags);
-
         /* No more mappings: invalidate P2M and add to balloon. */
         for (i = 0; i < nr_pages; i++) {
                 pfn = mfn_to_pfn(frame_list[i]);
-                set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
+                __set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
                 balloon_append(pfn_to_page(pfn));
         }
 
@@ -308,9 +321,7 @@ static int decrease_reservation(unsigned long nr_pages)
 
         balloon_stats.current_pages -= nr_pages;
 
-        spin_unlock_irqrestore(&xen_reservation_lock, flags);
-
-        return need_sleep;
+        return state;
 }
 
 /*
@@ -321,254 +332,145 @@ static int decrease_reservation(unsigned long nr_pages)
  */
 static void balloon_process(struct work_struct *work)
 {
-        int need_sleep = 0;
+        enum bp_state state = BP_DONE;
         long credit;
 
         mutex_lock(&balloon_mutex);
 
         do {
-                credit = current_target() - balloon_stats.current_pages;
+                credit = current_credit();
+
                 if (credit > 0)
-                        need_sleep = (increase_reservation(credit) != 0);
+                        state = increase_reservation(credit);
+
                 if (credit < 0)
-                        need_sleep = (decrease_reservation(-credit) != 0);
+                        state = decrease_reservation(-credit, GFP_BALLOON);
+
+                state = update_schedule(state);
 
 #ifndef CONFIG_PREEMPT
                 if (need_resched())
                         schedule();
 #endif
-        } while ((credit != 0) && !need_sleep);
+        } while (credit && state == BP_DONE);
 
         /* Schedule more work if there is some still to be done. */
-        if (current_target() != balloon_stats.current_pages)
-                mod_timer(&balloon_timer, jiffies + HZ);
+        if (state == BP_EAGAIN)
+                schedule_delayed_work(&balloon_worker, balloon_stats.schedule_delay * HZ);
 
         mutex_unlock(&balloon_mutex);
 }
 
 /* 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_work(&balloon_worker);
+        schedule_delayed_work(&balloon_worker, 0);
 }
+EXPORT_SYMBOL_GPL(balloon_set_new_target);
 
-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)
+/**
+ * alloc_xenballooned_pages - get pages that have been ballooned out
+ * @nr_pages: Number of pages to get
+ * @pages: pages returned
+ * @return 0 on success, error otherwise
+ */
+int alloc_xenballooned_pages(int nr_pages, struct page** pages)
 {
-        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;
+        int pgno = 0;
+        struct page* page;
+        mutex_lock(&balloon_mutex);
+        while (pgno < nr_pages) {
+                page = balloon_retrieve(true);
+                if (page) {
+                        pages[pgno++] = page;
+                } else {
+                        enum bp_state st;
+                        st = decrease_reservation(nr_pages - pgno, GFP_HIGHUSER);
+                        if (st != BP_DONE)
+                                goto out_undo;
+                }
         }
-
-        /* 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));
+        mutex_unlock(&balloon_mutex);
+        return 0;
+ out_undo:
+        while (pgno)
+                balloon_append(pages[--pgno]);
+        /* Free the memory back to the kernel soon */
+        schedule_delayed_work(&balloon_worker, 0);
+        mutex_unlock(&balloon_mutex);
+        return -ENOMEM;
 }
+EXPORT_SYMBOL(alloc_xenballooned_pages);
 
-static int balloon_init_watcher(struct notifier_block *notifier,
-                                unsigned long event,
-                                void *data)
+/**
+ * free_xenballooned_pages - return pages retrieved with get_ballooned_pages
+ * @nr_pages: Number of pages
+ * @pages: pages to return
+ */
+void free_xenballooned_pages(int nr_pages, struct page** pages)
 {
-        int err;
+        int i;
+
+        mutex_lock(&balloon_mutex);
 
-        err = register_xenbus_watch(&target_watch);
-        if (err)
-                printk(KERN_ERR "Failed to set balloon watcher\n");
+        for (i = 0; i < nr_pages; i++) {
+                if (pages[i])
+                        balloon_append(pages[i]);
+        }
 
-        return NOTIFY_DONE;
-}
+        /* The balloon may be too large now. Shrink it if needed. */
+        if (current_credit())
+                schedule_delayed_work(&balloon_worker, 0);
 
-static struct notifier_block xenstore_notifier;
+        mutex_unlock(&balloon_mutex);
+}
+EXPORT_SYMBOL(free_xenballooned_pages);
 
 static int __init balloon_init(void)
 {
-        unsigned long pfn;
+        unsigned long pfn, extra_pfn_end;
         struct page *page;
 
-        if (!xen_pv_domain())
+        if (!xen_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.current_pages = xen_pv_domain() ? min(xen_start_info->nr_pages, max_pfn) : max_pfn;
         balloon_stats.target_pages  = balloon_stats.current_pages;
         balloon_stats.balloon_low   = 0;
         balloon_stats.balloon_high  = 0;
-        balloon_stats.driver_pages  = 0UL;
-
-        init_timer(&balloon_timer);
-        balloon_timer.data = 0;
-        balloon_timer.function = balloon_alarm;
 
-        register_balloon(&balloon_sysdev);
+        balloon_stats.schedule_delay = 1;
+        balloon_stats.max_schedule_delay = 32;
+        balloon_stats.retry_count = 1;
+        balloon_stats.max_retry_count = RETRY_UNLIMITED;
 
-        /* Initialise the balloon with excess memory space. */
-        for (pfn = xen_start_info->nr_pages; pfn < max_pfn; pfn++) {
+        /*
+         * Initialise the balloon with excess memory space.  We need
+         * to make sure we don't add memory which doesn't exist or
+         * logically exist.  The E820 map can be trimmed to be smaller
+         * than the amount of physical memory due to the mem= command
+         * line parameter.  And if this is a 32-bit non-HIGHMEM kernel
+         * on a system with memory which requires highmem to access,
+         * don't try to use it.
+         */
+        extra_pfn_end = min(min(max_pfn, e820_end_of_ram_pfn()),
+                            (unsigned long)PFN_DOWN(xen_extra_mem_start + xen_extra_mem_size));
+        for (pfn = PFN_UP(xen_extra_mem_start);
+             pfn < extra_pfn_end;
+             pfn++) {
                 page = pfn_to_page(pfn);
-                if (!PageReserved(page))
-                        balloon_append(page);
+                /* totalram_pages and totalhigh_pages do not include the boot-time
+                   balloon extension, so don't subtract from it. */
+                __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));
-BALLOON_SHOW(driver_kb, "%lu\n", PAGES2KB(balloon_stats.driver_pages));
-
-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,
-};
-
-static struct attribute *balloon_info_attrs[] = {
-        &attr_current_kb.attr,
-        &attr_low_kb.attr,
-        &attr_high_kb.attr,
-        &attr_driver_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");