X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=kernel%2Fdrivers%2Fvirtio%2Fvirtio_balloon.c;fp=kernel%2Fdrivers%2Fvirtio%2Fvirtio_balloon.c;h=82e80e034f250b88993af25bb27434c2a78f8204;hb=9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00;hp=0000000000000000000000000000000000000000;hpb=98260f3884f4a202f9ca5eabed40b1354c489b29;p=kvmfornfv.git diff --git a/kernel/drivers/virtio/virtio_balloon.c b/kernel/drivers/virtio/virtio_balloon.c new file mode 100644 index 000000000..82e80e034 --- /dev/null +++ b/kernel/drivers/virtio/virtio_balloon.c @@ -0,0 +1,618 @@ +/* + * Virtio balloon implementation, inspired by Dor Laor and Marcelo + * Tosatti's implementations. + * + * Copyright 2008 Rusty Russell IBM Corporation + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* + * 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 +#define OOM_VBALLOON_DEFAULT_PAGES 256 +#define VIRTBALLOON_OOM_NOTIFY_PRIORITY 80 + +static int oom_pages = OOM_VBALLOON_DEFAULT_PAGES; +module_param(oom_pages, int, S_IRUSR | S_IWUSR); +MODULE_PARM_DESC(oom_pages, "pages to free on OOM"); + +struct virtio_balloon { + struct virtio_device *vdev; + struct virtqueue *inflate_vq, *deflate_vq, *stats_vq; + + /* Where the ballooning thread waits for config to change. */ + wait_queue_head_t config_change; + + /* The thread servicing the balloon. */ + struct task_struct *thread; + + /* Waiting for host to ack the pages we released. */ + wait_queue_head_t acked; + + /* Number of balloon pages we've told the Host we're not using. */ + unsigned int num_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[VIRTIO_BALLOON_ARRAY_PFNS_MAX]; + + /* Memory statistics */ + int need_stats_update; + struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR]; + + /* To register callback in oom notifier call chain */ + struct notifier_block nb; +}; + +static struct virtio_device_id id_table[] = { + { VIRTIO_ID_BALLOON, VIRTIO_DEV_ANY_ID }, + { 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 = vq->vdev->priv; + + 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); + + /* We should always be able to add one buffer to an empty queue. */ + virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL); + virtqueue_kick(vq); + + /* When host has read buffer, this completes via balloon_ack */ + 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)); + + 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) { + 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; + } + set_page_pfns(vb->pfns + vb->num_pfns, page); + vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE; + adjust_managed_page_count(page, -1); + } + + /* 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; + + /* Find pfns pointing at start of each page, get pages and free them. */ + for (i = 0; i < num; i += VIRTIO_BALLOON_PAGES_PER_PAGE) { + struct page *page = balloon_pfn_to_page(pfns[i]); + adjust_managed_page_count(page, 1); + put_page(page); /* balloon reference */ + } +} + +static unsigned leak_balloon(struct virtio_balloon *vb, size_t num) +{ + unsigned num_freed_pages; + 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)); + + 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; + } + + num_freed_pages = vb->num_pfns; + /* + * 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); + mutex_unlock(&vb->balloon_lock); + release_pages_by_pfn(vb->pfns, vb->num_pfns); + return num_freed_pages; +} + +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 = cpu_to_virtio16(vb->vdev, tag); + vb->stats[idx].val = cpu_to_virtio64(vb->vdev, 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)); + virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL); + virtqueue_kick(vq); +} + +static void virtballoon_changed(struct virtio_device *vdev) +{ + struct virtio_balloon *vb = vdev->priv; + + wake_up(&vb->config_change); +} + +static inline s64 towards_target(struct virtio_balloon *vb) +{ + s64 target; + u32 num_pages; + + virtio_cread(vb->vdev, struct virtio_balloon_config, num_pages, + &num_pages); + + /* Legacy balloon config space is LE, unlike all other devices. */ + if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1)) + num_pages = le32_to_cpu((__force __le32)num_pages); + + target = num_pages; + return target - vb->num_pages; +} + +static void update_balloon_size(struct virtio_balloon *vb) +{ + u32 actual = vb->num_pages; + + /* Legacy balloon config space is LE, unlike all other devices. */ + if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1)) + actual = (__force u32)cpu_to_le32(actual); + + virtio_cwrite(vb->vdev, struct virtio_balloon_config, actual, + &actual); +} + +/* + * virtballoon_oom_notify - release pages when system is under severe + * memory pressure (called from out_of_memory()) + * @self : notifier block struct + * @dummy: not used + * @parm : returned - number of freed pages + * + * The balancing of memory by use of the virtio balloon should not cause + * the termination of processes while there are pages in the balloon. + * If virtio balloon manages to release some memory, it will make the + * system return and retry the allocation that forced the OOM killer + * to run. + */ +static int virtballoon_oom_notify(struct notifier_block *self, + unsigned long dummy, void *parm) +{ + struct virtio_balloon *vb; + unsigned long *freed; + unsigned num_freed_pages; + + vb = container_of(self, struct virtio_balloon, nb); + if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) + return NOTIFY_OK; + + freed = parm; + num_freed_pages = leak_balloon(vb, oom_pages); + update_balloon_size(vb); + *freed += num_freed_pages; + + return NOTIFY_OK; +} + +static int balloon(void *_vballoon) +{ + struct virtio_balloon *vb = _vballoon; + DEFINE_WAIT_FUNC(wait, woken_wake_function); + + set_freezable(); + while (!kthread_should_stop()) { + s64 diff; + + try_to_freeze(); + + add_wait_queue(&vb->config_change, &wait); + for (;;) { + if ((diff = towards_target(vb)) != 0 || + vb->need_stats_update || + kthread_should_stop() || + freezing(current)) + break; + wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); + } + remove_wait_queue(&vb->config_change, &wait); + + if (vb->need_stats_update) + stats_handle_request(vb); + if (diff > 0) + fill_balloon(vb, diff); + else if (diff < 0) + leak_balloon(vb, -diff); + update_balloon_size(vb); + + /* + * For large balloon changes, we could spend a lot of time + * and always have work to do. Be nice if preempt disabled. + */ + cond_resched(); + } + 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 (it can't be broken yet!). + */ + 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; +} + +#ifdef CONFIG_BALLOON_COMPACTION +/* + * virtballoon_migratepage - perform the balloon page migration on behalf of + * a compation thread. (called under page lock) + * @vb_dev_info: the balloon device + * @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 + */ +static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info, + struct page *newpage, struct page *page, enum migrate_mode mode) +{ + struct virtio_balloon *vb = container_of(vb_dev_info, + struct virtio_balloon, vb_dev_info); + unsigned long flags; + + /* + * 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; + + get_page(newpage); /* balloon reference */ + + /* balloon's page migration 1st step -- inflate "newpage" */ + spin_lock_irqsave(&vb_dev_info->pages_lock, flags); + balloon_page_insert(vb_dev_info, newpage); + vb_dev_info->isolated_pages--; + __count_vm_event(BALLOON_MIGRATE); + 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" */ + 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); + + put_page(page); /* balloon reference */ + + return MIGRATEPAGE_SUCCESS; +} +#endif /* CONFIG_BALLOON_COMPACTION */ + +static int virtballoon_probe(struct virtio_device *vdev) +{ + struct virtio_balloon *vb; + int err; + + if (!vdev->config->get) { + dev_err(&vdev->dev, "%s failure: config access disabled\n", + __func__); + return -EINVAL; + } + + vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL); + if (!vb) { + err = -ENOMEM; + goto out; + } + + 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; + + balloon_devinfo_init(&vb->vb_dev_info); +#ifdef CONFIG_BALLOON_COMPACTION + vb->vb_dev_info.migratepage = virtballoon_migratepage; +#endif + + err = init_vqs(vb); + if (err) + goto out_free_vb; + + vb->nb.notifier_call = virtballoon_oom_notify; + vb->nb.priority = VIRTBALLOON_OOM_NOTIFY_PRIORITY; + err = register_oom_notifier(&vb->nb); + if (err < 0) + goto out_oom_notify; + + virtio_device_ready(vdev); + + vb->thread = kthread_run(balloon, vb, "vballoon"); + if (IS_ERR(vb->thread)) { + err = PTR_ERR(vb->thread); + goto out_del_vqs; + } + + return 0; + +out_del_vqs: + unregister_oom_notifier(&vb->nb); +out_oom_notify: + vdev->config->del_vqs(vdev); +out_free_vb: + kfree(vb); +out: + return err; +} + +static void remove_common(struct virtio_balloon *vb) +{ + /* 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. */ + vb->vdev->config->reset(vb->vdev); + + vb->vdev->config->del_vqs(vb->vdev); +} + +static void virtballoon_remove(struct virtio_device *vdev) +{ + struct virtio_balloon *vb = vdev->priv; + + unregister_oom_notifier(&vb->nb); + kthread_stop(vb->thread); + remove_common(vb); + kfree(vb); +} + +#ifdef CONFIG_PM_SLEEP +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; + + virtio_device_ready(vdev); + + 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, + VIRTIO_BALLOON_F_DEFLATE_ON_OOM, +}; + +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 = virtballoon_remove, + .config_changed = virtballoon_changed, +#ifdef CONFIG_PM_SLEEP + .freeze = virtballoon_freeze, + .restore = virtballoon_restore, +#endif +}; + +module_virtio_driver(virtio_balloon_driver); +MODULE_DEVICE_TABLE(virtio, id_table); +MODULE_DESCRIPTION("Virtio balloon driver"); +MODULE_LICENSE("GPL");