-/* Virtio balloon implementation, inspired by Dor Loar and Marcelo
+/*
+ * Virtio balloon implementation, inspired by Dor Laor and Marcelo
* Tosatti's implementations.
*
* Copyright 2008 Rusty Russell IBM Corporation
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
-//#define DEBUG
+
#include <linux/virtio.h>
#include <linux/virtio_balloon.h>
#include <linux/swap.h>
#include <linux/kthread.h>
#include <linux/freezer.h>
#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/balloon_compaction.h>
+
+/*
+ * Balloon device works in 4K page units. So each page is pointed to by
+ * multiple balloon pages. All memory counters in this driver are in balloon
+ * page units.
+ */
+#define VIRTIO_BALLOON_PAGES_PER_PAGE (unsigned)(PAGE_SIZE >> VIRTIO_BALLOON_PFN_SHIFT)
+#define VIRTIO_BALLOON_ARRAY_PFNS_MAX 256
struct virtio_balloon
{
struct virtio_device *vdev;
- struct virtqueue *inflate_vq, *deflate_vq;
+ struct virtqueue *inflate_vq, *deflate_vq, *stats_vq;
/* Where the ballooning thread waits for config to change. */
wait_queue_head_t config_change;
struct task_struct *thread;
/* Waiting for host to ack the pages we released. */
- struct completion acked;
+ wait_queue_head_t acked;
- /* Do we have to tell Host *before* we reuse pages? */
- bool tell_host_first;
-
- /* The pages we've told the Host we're not using. */
+ /* Number of balloon pages we've told the Host we're not using. */
unsigned int num_pages;
- struct list_head pages;
+ /*
+ * The pages we've told the Host we're not using are enqueued
+ * at vb_dev_info->pages list.
+ * Each page on this list adds VIRTIO_BALLOON_PAGES_PER_PAGE
+ * to num_pages above.
+ */
+ struct balloon_dev_info *vb_dev_info;
+
+ /* Synchronize access/update to this struct virtio_balloon elements */
+ struct mutex balloon_lock;
/* The array of pfns we tell the Host about. */
unsigned int num_pfns;
- u32 pfns[256];
+ u32 pfns[VIRTIO_BALLOON_ARRAY_PFNS_MAX];
+
+ /* Memory statistics */
+ int need_stats_update;
+ struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
};
static struct virtio_device_id id_table[] = {
{ 0 },
};
+static u32 page_to_balloon_pfn(struct page *page)
+{
+ unsigned long pfn = page_to_pfn(page);
+
+ BUILD_BUG_ON(PAGE_SHIFT < VIRTIO_BALLOON_PFN_SHIFT);
+ /* Convert pfn from Linux page size to balloon page size. */
+ return pfn * VIRTIO_BALLOON_PAGES_PER_PAGE;
+}
+
+static struct page *balloon_pfn_to_page(u32 pfn)
+{
+ BUG_ON(pfn % VIRTIO_BALLOON_PAGES_PER_PAGE);
+ return pfn_to_page(pfn / VIRTIO_BALLOON_PAGES_PER_PAGE);
+}
+
static void balloon_ack(struct virtqueue *vq)
{
- struct virtio_balloon *vb;
- unsigned int len;
+ struct virtio_balloon *vb = vq->vdev->priv;
- vb = vq->vq_ops->get_buf(vq, &len);
- if (vb)
- complete(&vb->acked);
+ wake_up(&vb->acked);
}
static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq)
{
struct scatterlist sg;
+ unsigned int len;
sg_init_one(&sg, vb->pfns, sizeof(vb->pfns[0]) * vb->num_pfns);
- init_completion(&vb->acked);
-
/* We should always be able to add one buffer to an empty queue. */
- if (vq->vq_ops->add_buf(vq, &sg, 1, 0, vb) != 0)
+ if (virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL) < 0)
BUG();
- vq->vq_ops->kick(vq);
+ virtqueue_kick(vq);
/* When host has read buffer, this completes via balloon_ack */
- wait_for_completion(&vb->acked);
+ wait_event(vb->acked, virtqueue_get_buf(vq, &len));
+}
+
+static void set_page_pfns(u32 pfns[], struct page *page)
+{
+ unsigned int i;
+
+ /* Set balloon pfns pointing at this page.
+ * Note that the first pfn points at start of the page. */
+ for (i = 0; i < VIRTIO_BALLOON_PAGES_PER_PAGE; i++)
+ pfns[i] = page_to_balloon_pfn(page) + i;
}
static void fill_balloon(struct virtio_balloon *vb, size_t num)
{
+ struct balloon_dev_info *vb_dev_info = vb->vb_dev_info;
+
/* We can only do one array worth at a time. */
num = min(num, ARRAY_SIZE(vb->pfns));
- for (vb->num_pfns = 0; vb->num_pfns < num; vb->num_pfns++) {
- struct page *page = alloc_page(GFP_HIGHUSER | __GFP_NORETRY);
+ mutex_lock(&vb->balloon_lock);
+ for (vb->num_pfns = 0; vb->num_pfns < num;
+ vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) {
+ struct page *page = balloon_page_enqueue(vb_dev_info);
+
if (!page) {
- if (printk_ratelimit())
- dev_printk(KERN_INFO, &vb->vdev->dev,
- "Out of puff! Can't get %zu pages\n",
- num);
+ dev_info_ratelimited(&vb->vdev->dev,
+ "Out of puff! Can't get %u pages\n",
+ VIRTIO_BALLOON_PAGES_PER_PAGE);
/* Sleep for at least 1/5 of a second before retry. */
msleep(200);
break;
}
- vb->pfns[vb->num_pfns] = page_to_pfn(page);
+ set_page_pfns(vb->pfns + vb->num_pfns, page);
+ vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE;
totalram_pages--;
- vb->num_pages++;
- list_add(&page->lru, &vb->pages);
}
- /* Didn't get any? Oh well. */
- if (vb->num_pfns == 0)
- return;
-
- tell_host(vb, vb->inflate_vq);
+ /* Did we get any? */
+ if (vb->num_pfns != 0)
+ tell_host(vb, vb->inflate_vq);
+ mutex_unlock(&vb->balloon_lock);
}
static void release_pages_by_pfn(const u32 pfns[], unsigned int num)
{
unsigned int i;
- for (i = 0; i < num; i++) {
- __free_page(pfn_to_page(pfns[i]));
+ /* Find pfns pointing at start of each page, get pages and free them. */
+ for (i = 0; i < num; i += VIRTIO_BALLOON_PAGES_PER_PAGE) {
+ balloon_page_free(balloon_pfn_to_page(pfns[i]));
totalram_pages++;
}
}
static void leak_balloon(struct virtio_balloon *vb, size_t num)
{
struct page *page;
+ struct balloon_dev_info *vb_dev_info = vb->vb_dev_info;
/* We can only do one array worth at a time. */
num = min(num, ARRAY_SIZE(vb->pfns));
- for (vb->num_pfns = 0; vb->num_pfns < num; vb->num_pfns++) {
- page = list_first_entry(&vb->pages, struct page, lru);
- list_del(&page->lru);
- vb->pfns[vb->num_pfns] = page_to_pfn(page);
- vb->num_pages--;
+ mutex_lock(&vb->balloon_lock);
+ for (vb->num_pfns = 0; vb->num_pfns < num;
+ vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) {
+ page = balloon_page_dequeue(vb_dev_info);
+ if (!page)
+ break;
+ set_page_pfns(vb->pfns + vb->num_pfns, page);
+ vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE;
}
- if (vb->tell_host_first) {
+ /*
+ * Note that if
+ * virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST);
+ * is true, we *have* to do it in this order
+ */
+ if (vb->num_pfns != 0)
tell_host(vb, vb->deflate_vq);
- release_pages_by_pfn(vb->pfns, vb->num_pfns);
- } else {
- release_pages_by_pfn(vb->pfns, vb->num_pfns);
- tell_host(vb, vb->deflate_vq);
- }
+ mutex_unlock(&vb->balloon_lock);
+ release_pages_by_pfn(vb->pfns, vb->num_pfns);
+}
+
+static inline void update_stat(struct virtio_balloon *vb, int idx,
+ u16 tag, u64 val)
+{
+ BUG_ON(idx >= VIRTIO_BALLOON_S_NR);
+ vb->stats[idx].tag = tag;
+ vb->stats[idx].val = val;
+}
+
+#define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT)
+
+static void update_balloon_stats(struct virtio_balloon *vb)
+{
+ unsigned long events[NR_VM_EVENT_ITEMS];
+ struct sysinfo i;
+ int idx = 0;
+
+ all_vm_events(events);
+ si_meminfo(&i);
+
+ update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN,
+ pages_to_bytes(events[PSWPIN]));
+ update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT,
+ pages_to_bytes(events[PSWPOUT]));
+ update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]);
+ update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]);
+ update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE,
+ pages_to_bytes(i.freeram));
+ update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT,
+ pages_to_bytes(i.totalram));
+}
+
+/*
+ * While most virtqueues communicate guest-initiated requests to the hypervisor,
+ * the stats queue operates in reverse. The driver initializes the virtqueue
+ * with a single buffer. From that point forward, all conversations consist of
+ * a hypervisor request (a call to this function) which directs us to refill
+ * the virtqueue with a fresh stats buffer. Since stats collection can sleep,
+ * we notify our kthread which does the actual work via stats_handle_request().
+ */
+static void stats_request(struct virtqueue *vq)
+{
+ struct virtio_balloon *vb = vq->vdev->priv;
+
+ vb->need_stats_update = 1;
+ wake_up(&vb->config_change);
+}
+
+static void stats_handle_request(struct virtio_balloon *vb)
+{
+ struct virtqueue *vq;
+ struct scatterlist sg;
+ unsigned int len;
+
+ vb->need_stats_update = 0;
+ update_balloon_stats(vb);
+
+ vq = vb->stats_vq;
+ if (!virtqueue_get_buf(vq, &len))
+ return;
+ sg_init_one(&sg, vb->stats, sizeof(vb->stats));
+ if (virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL) < 0)
+ BUG();
+ virtqueue_kick(vq);
}
static void virtballoon_changed(struct virtio_device *vdev)
wake_up(&vb->config_change);
}
-static inline int towards_target(struct virtio_balloon *vb)
+static inline s64 towards_target(struct virtio_balloon *vb)
{
- u32 v;
- __virtio_config_val(vb->vdev,
- offsetof(struct virtio_balloon_config, num_pages),
- &v);
- return v - vb->num_pages;
+ __le32 v;
+ s64 target;
+
+ vb->vdev->config->get(vb->vdev,
+ offsetof(struct virtio_balloon_config, num_pages),
+ &v, sizeof(v));
+ target = le32_to_cpu(v);
+ return target - vb->num_pages;
}
static void update_balloon_size(struct virtio_balloon *vb)
set_freezable();
while (!kthread_should_stop()) {
- int diff;
+ s64 diff;
try_to_freeze();
wait_event_interruptible(vb->config_change,
(diff = towards_target(vb)) != 0
- || kthread_should_stop());
+ || vb->need_stats_update
+ || kthread_should_stop()
+ || freezing(current));
+ if (vb->need_stats_update)
+ stats_handle_request(vb);
if (diff > 0)
fill_balloon(vb, diff);
else if (diff < 0)
return 0;
}
+static int init_vqs(struct virtio_balloon *vb)
+{
+ struct virtqueue *vqs[3];
+ vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request };
+ const char *names[] = { "inflate", "deflate", "stats" };
+ int err, nvqs;
+
+ /*
+ * We expect two virtqueues: inflate and deflate, and
+ * optionally stat.
+ */
+ nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2;
+ err = vb->vdev->config->find_vqs(vb->vdev, nvqs, vqs, callbacks, names);
+ if (err)
+ return err;
+
+ vb->inflate_vq = vqs[0];
+ vb->deflate_vq = vqs[1];
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
+ struct scatterlist sg;
+ vb->stats_vq = vqs[2];
+
+ /*
+ * Prime this virtqueue with one buffer so the hypervisor can
+ * use it to signal us later.
+ */
+ sg_init_one(&sg, vb->stats, sizeof vb->stats);
+ if (virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb, GFP_KERNEL)
+ < 0)
+ BUG();
+ virtqueue_kick(vb->stats_vq);
+ }
+ return 0;
+}
+
+static const struct address_space_operations virtio_balloon_aops;
+#ifdef CONFIG_BALLOON_COMPACTION
+/*
+ * virtballoon_migratepage - perform the balloon page migration on behalf of
+ * a compation thread. (called under page lock)
+ * @mapping: the page->mapping which will be assigned to the new migrated page.
+ * @newpage: page that will replace the isolated page after migration finishes.
+ * @page : the isolated (old) page that is about to be migrated to newpage.
+ * @mode : compaction mode -- not used for balloon page migration.
+ *
+ * After a ballooned page gets isolated by compaction procedures, this is the
+ * function that performs the page migration on behalf of a compaction thread
+ * The page migration for virtio balloon is done in a simple swap fashion which
+ * follows these two macro steps:
+ * 1) insert newpage into vb->pages list and update the host about it;
+ * 2) update the host about the old page removed from vb->pages list;
+ *
+ * This function preforms the balloon page migration task.
+ * Called through balloon_mapping->a_ops->migratepage
+ */
+int virtballoon_migratepage(struct address_space *mapping,
+ struct page *newpage, struct page *page, enum migrate_mode mode)
+{
+ struct balloon_dev_info *vb_dev_info = balloon_page_device(page);
+ struct virtio_balloon *vb;
+ unsigned long flags;
+
+ BUG_ON(!vb_dev_info);
+
+ vb = vb_dev_info->balloon_device;
+
+ /*
+ * In order to avoid lock contention while migrating pages concurrently
+ * to leak_balloon() or fill_balloon() we just give up the balloon_lock
+ * this turn, as it is easier to retry the page migration later.
+ * This also prevents fill_balloon() getting stuck into a mutex
+ * recursion in the case it ends up triggering memory compaction
+ * while it is attempting to inflate the ballon.
+ */
+ if (!mutex_trylock(&vb->balloon_lock))
+ return -EAGAIN;
+
+ /* balloon's page migration 1st step -- inflate "newpage" */
+ spin_lock_irqsave(&vb_dev_info->pages_lock, flags);
+ balloon_page_insert(newpage, mapping, &vb_dev_info->pages);
+ vb_dev_info->isolated_pages--;
+ spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags);
+ vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
+ set_page_pfns(vb->pfns, newpage);
+ tell_host(vb, vb->inflate_vq);
+
+ /*
+ * balloon's page migration 2nd step -- deflate "page"
+ *
+ * It's safe to delete page->lru here because this page is at
+ * an isolated migration list, and this step is expected to happen here
+ */
+ balloon_page_delete(page);
+ vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
+ set_page_pfns(vb->pfns, page);
+ tell_host(vb, vb->deflate_vq);
+
+ mutex_unlock(&vb->balloon_lock);
+
+ return MIGRATEPAGE_BALLOON_SUCCESS;
+}
+
+/* define the balloon_mapping->a_ops callback to allow balloon page migration */
+static const struct address_space_operations virtio_balloon_aops = {
+ .migratepage = virtballoon_migratepage,
+};
+#endif /* CONFIG_BALLOON_COMPACTION */
+
static int virtballoon_probe(struct virtio_device *vdev)
{
struct virtio_balloon *vb;
+ struct address_space *vb_mapping;
+ struct balloon_dev_info *vb_devinfo;
int err;
vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL);
goto out;
}
- INIT_LIST_HEAD(&vb->pages);
vb->num_pages = 0;
+ mutex_init(&vb->balloon_lock);
init_waitqueue_head(&vb->config_change);
+ init_waitqueue_head(&vb->acked);
vb->vdev = vdev;
+ vb->need_stats_update = 0;
- /* We expect two virtqueues. */
- vb->inflate_vq = vdev->config->find_vq(vdev, 0, balloon_ack);
- if (IS_ERR(vb->inflate_vq)) {
- err = PTR_ERR(vb->inflate_vq);
+ vb_devinfo = balloon_devinfo_alloc(vb);
+ if (IS_ERR(vb_devinfo)) {
+ err = PTR_ERR(vb_devinfo);
goto out_free_vb;
}
- vb->deflate_vq = vdev->config->find_vq(vdev, 1, balloon_ack);
- if (IS_ERR(vb->deflate_vq)) {
- err = PTR_ERR(vb->deflate_vq);
- goto out_del_inflate_vq;
+ vb_mapping = balloon_mapping_alloc(vb_devinfo,
+ (balloon_compaction_check()) ?
+ &virtio_balloon_aops : NULL);
+ if (IS_ERR(vb_mapping)) {
+ /*
+ * IS_ERR(vb_mapping) && PTR_ERR(vb_mapping) == -EOPNOTSUPP
+ * This means !CONFIG_BALLOON_COMPACTION, otherwise we get off.
+ */
+ err = PTR_ERR(vb_mapping);
+ if (err != -EOPNOTSUPP)
+ goto out_free_vb_devinfo;
}
+ vb->vb_dev_info = vb_devinfo;
+
+ err = init_vqs(vb);
+ if (err)
+ goto out_free_vb_mapping;
+
vb->thread = kthread_run(balloon, vb, "vballoon");
if (IS_ERR(vb->thread)) {
err = PTR_ERR(vb->thread);
- goto out_del_deflate_vq;
+ goto out_del_vqs;
}
- vb->tell_host_first
- = vdev->config->feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST);
-
return 0;
-out_del_deflate_vq:
- vdev->config->del_vq(vb->deflate_vq);
-out_del_inflate_vq:
- vdev->config->del_vq(vb->inflate_vq);
+out_del_vqs:
+ vdev->config->del_vqs(vdev);
+out_free_vb_mapping:
+ balloon_mapping_free(vb_mapping);
+out_free_vb_devinfo:
+ balloon_devinfo_free(vb_devinfo);
out_free_vb:
kfree(vb);
out:
return err;
}
-static void virtballoon_remove(struct virtio_device *vdev)
+static void remove_common(struct virtio_balloon *vb)
{
- struct virtio_balloon *vb = vdev->priv;
-
- kthread_stop(vb->thread);
-
/* There might be pages left in the balloon: free them. */
while (vb->num_pages)
leak_balloon(vb, vb->num_pages);
+ update_balloon_size(vb);
/* Now we reset the device so we can clean up the queues. */
- vdev->config->reset(vdev);
+ vb->vdev->config->reset(vb->vdev);
- vdev->config->del_vq(vb->deflate_vq);
- vdev->config->del_vq(vb->inflate_vq);
+ vb->vdev->config->del_vqs(vb->vdev);
+}
+
+static void virtballoon_remove(struct virtio_device *vdev)
+{
+ struct virtio_balloon *vb = vdev->priv;
+
+ kthread_stop(vb->thread);
+ remove_common(vb);
+ balloon_mapping_free(vb->vb_dev_info->mapping);
+ balloon_devinfo_free(vb->vb_dev_info);
kfree(vb);
}
-static struct virtio_driver virtio_balloon = {
+#ifdef CONFIG_PM
+static int virtballoon_freeze(struct virtio_device *vdev)
+{
+ struct virtio_balloon *vb = vdev->priv;
+
+ /*
+ * The kthread is already frozen by the PM core before this
+ * function is called.
+ */
+
+ remove_common(vb);
+ return 0;
+}
+
+static int virtballoon_restore(struct virtio_device *vdev)
+{
+ struct virtio_balloon *vb = vdev->priv;
+ int ret;
+
+ ret = init_vqs(vdev->priv);
+ if (ret)
+ return ret;
+
+ fill_balloon(vb, towards_target(vb));
+ update_balloon_size(vb);
+ return 0;
+}
+#endif
+
+static unsigned int features[] = {
+ VIRTIO_BALLOON_F_MUST_TELL_HOST,
+ VIRTIO_BALLOON_F_STATS_VQ,
+};
+
+static struct virtio_driver virtio_balloon_driver = {
+ .feature_table = features,
+ .feature_table_size = ARRAY_SIZE(features),
.driver.name = KBUILD_MODNAME,
.driver.owner = THIS_MODULE,
.id_table = id_table,
.probe = virtballoon_probe,
- .remove = __devexit_p(virtballoon_remove),
+ .remove = virtballoon_remove,
.config_changed = virtballoon_changed,
+#ifdef CONFIG_PM
+ .freeze = virtballoon_freeze,
+ .restore = virtballoon_restore,
+#endif
};
-static int __init init(void)
-{
- return register_virtio_driver(&virtio_balloon);
-}
-
-static void __exit fini(void)
-{
- unregister_virtio_driver(&virtio_balloon);
-}
-module_init(init);
-module_exit(fini);
-
+module_virtio_driver(virtio_balloon_driver);
MODULE_DEVICE_TABLE(virtio, id_table);
MODULE_DESCRIPTION("Virtio balloon driver");
MODULE_LICENSE("GPL");
Code Review / linux-3.10.git / blobdiff