diff options
| -rw-r--r-- | drivers/virtio/virtio_balloon.c | 364 | ||||
| -rw-r--r-- | include/uapi/linux/virtio_balloon.h | 5 |
2 files changed, 336 insertions, 33 deletions
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index d1c1f6283729..a18567889289 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -41,13 +41,34 @@ #define VIRTIO_BALLOON_ARRAY_PFNS_MAX 256 #define VIRTBALLOON_OOM_NOTIFY_PRIORITY 80 +#define VIRTIO_BALLOON_FREE_PAGE_ALLOC_FLAG (__GFP_NORETRY | __GFP_NOWARN | \ + __GFP_NOMEMALLOC) +/* The order of free page blocks to report to host */ +#define VIRTIO_BALLOON_FREE_PAGE_ORDER (MAX_ORDER - 1) +/* The size of a free page block in bytes */ +#define VIRTIO_BALLOON_FREE_PAGE_SIZE \ + (1 << (VIRTIO_BALLOON_FREE_PAGE_ORDER + PAGE_SHIFT)) + #ifdef CONFIG_BALLOON_COMPACTION static struct vfsmount *balloon_mnt; #endif +enum virtio_balloon_vq { + VIRTIO_BALLOON_VQ_INFLATE, + VIRTIO_BALLOON_VQ_DEFLATE, + VIRTIO_BALLOON_VQ_STATS, + VIRTIO_BALLOON_VQ_FREE_PAGE, + VIRTIO_BALLOON_VQ_MAX +}; + struct virtio_balloon { struct virtio_device *vdev; - struct virtqueue *inflate_vq, *deflate_vq, *stats_vq; + struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq; + + /* Balloon's own wq for cpu-intensive work items */ + struct workqueue_struct *balloon_wq; + /* The free page reporting work item submitted to the balloon wq */ + struct work_struct report_free_page_work; /* The balloon servicing is delegated to a freezable workqueue. */ struct work_struct update_balloon_stats_work; @@ -57,6 +78,18 @@ struct virtio_balloon { spinlock_t stop_update_lock; bool stop_update; + /* The list of allocated free pages, waiting to be given back to mm */ + struct list_head free_page_list; + spinlock_t free_page_list_lock; + /* The number of free page blocks on the above list */ + unsigned long num_free_page_blocks; + /* The cmd id received from host */ + u32 cmd_id_received; + /* The cmd id that is actively in use */ + __virtio32 cmd_id_active; + /* Buffer to store the stop sign */ + __virtio32 cmd_id_stop; + /* Waiting for host to ack the pages we released. */ wait_queue_head_t acked; @@ -320,17 +353,6 @@ static void stats_handle_request(struct virtio_balloon *vb) virtqueue_kick(vq); } -static void virtballoon_changed(struct virtio_device *vdev) -{ - struct virtio_balloon *vb = vdev->priv; - unsigned long flags; - - spin_lock_irqsave(&vb->stop_update_lock, flags); - if (!vb->stop_update) - queue_work(system_freezable_wq, &vb->update_balloon_size_work); - spin_unlock_irqrestore(&vb->stop_update_lock, flags); -} - static inline s64 towards_target(struct virtio_balloon *vb) { s64 target; @@ -347,6 +369,60 @@ static inline s64 towards_target(struct virtio_balloon *vb) return target - vb->num_pages; } +/* Gives back @num_to_return blocks of free pages to mm. */ +static unsigned long return_free_pages_to_mm(struct virtio_balloon *vb, + unsigned long num_to_return) +{ + struct page *page; + unsigned long num_returned; + + spin_lock_irq(&vb->free_page_list_lock); + for (num_returned = 0; num_returned < num_to_return; num_returned++) { + page = balloon_page_pop(&vb->free_page_list); + if (!page) + break; + free_pages((unsigned long)page_address(page), + VIRTIO_BALLOON_FREE_PAGE_ORDER); + } + vb->num_free_page_blocks -= num_returned; + spin_unlock_irq(&vb->free_page_list_lock); + + return num_returned; +} + +static void virtballoon_changed(struct virtio_device *vdev) +{ + struct virtio_balloon *vb = vdev->priv; + unsigned long flags; + s64 diff = towards_target(vb); + + if (diff) { + spin_lock_irqsave(&vb->stop_update_lock, flags); + if (!vb->stop_update) + queue_work(system_freezable_wq, + &vb->update_balloon_size_work); + spin_unlock_irqrestore(&vb->stop_update_lock, flags); + } + + if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) { + virtio_cread(vdev, struct virtio_balloon_config, + free_page_report_cmd_id, &vb->cmd_id_received); + if (vb->cmd_id_received == VIRTIO_BALLOON_CMD_ID_DONE) { + /* Pass ULONG_MAX to give back all the free pages */ + return_free_pages_to_mm(vb, ULONG_MAX); + } else if (vb->cmd_id_received != VIRTIO_BALLOON_CMD_ID_STOP && + vb->cmd_id_received != + virtio32_to_cpu(vdev, vb->cmd_id_active)) { + spin_lock_irqsave(&vb->stop_update_lock, flags); + if (!vb->stop_update) { + queue_work(vb->balloon_wq, + &vb->report_free_page_work); + } + spin_unlock_irqrestore(&vb->stop_update_lock, flags); + } + } +} + static void update_balloon_size(struct virtio_balloon *vb) { u32 actual = vb->num_pages; @@ -389,26 +465,44 @@ static void update_balloon_size_func(struct work_struct *work) static int init_vqs(struct virtio_balloon *vb) { - struct virtqueue *vqs[3]; - vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request }; - static const char * const names[] = { "inflate", "deflate", "stats" }; - int err, nvqs; + struct virtqueue *vqs[VIRTIO_BALLOON_VQ_MAX]; + vq_callback_t *callbacks[VIRTIO_BALLOON_VQ_MAX]; + const char *names[VIRTIO_BALLOON_VQ_MAX]; + int err; /* - * We expect two virtqueues: inflate and deflate, and - * optionally stat. + * Inflateq and deflateq are used unconditionally. The names[] + * will be NULL if the related feature is not enabled, which will + * cause no allocation for the corresponding virtqueue in find_vqs. */ - nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2; - err = virtio_find_vqs(vb->vdev, nvqs, vqs, callbacks, names, NULL); + callbacks[VIRTIO_BALLOON_VQ_INFLATE] = balloon_ack; + names[VIRTIO_BALLOON_VQ_INFLATE] = "inflate"; + callbacks[VIRTIO_BALLOON_VQ_DEFLATE] = balloon_ack; + names[VIRTIO_BALLOON_VQ_DEFLATE] = "deflate"; + names[VIRTIO_BALLOON_VQ_STATS] = NULL; + names[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; + + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { + names[VIRTIO_BALLOON_VQ_STATS] = "stats"; + callbacks[VIRTIO_BALLOON_VQ_STATS] = stats_request; + } + + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) { + names[VIRTIO_BALLOON_VQ_FREE_PAGE] = "free_page_vq"; + callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; + } + + err = vb->vdev->config->find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX, + vqs, callbacks, names, NULL, NULL); if (err) return err; - vb->inflate_vq = vqs[0]; - vb->deflate_vq = vqs[1]; + vb->inflate_vq = vqs[VIRTIO_BALLOON_VQ_INFLATE]; + vb->deflate_vq = vqs[VIRTIO_BALLOON_VQ_DEFLATE]; if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { struct scatterlist sg; unsigned int num_stats; - vb->stats_vq = vqs[2]; + vb->stats_vq = vqs[VIRTIO_BALLOON_VQ_STATS]; /* * Prime this virtqueue with one buffer so the hypervisor can @@ -426,9 +520,145 @@ static int init_vqs(struct virtio_balloon *vb) } virtqueue_kick(vb->stats_vq); } + + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) + vb->free_page_vq = vqs[VIRTIO_BALLOON_VQ_FREE_PAGE]; + + return 0; +} + +static int send_cmd_id_start(struct virtio_balloon *vb) +{ + struct scatterlist sg; + struct virtqueue *vq = vb->free_page_vq; + int err, unused; + + /* Detach all the used buffers from the vq */ + while (virtqueue_get_buf(vq, &unused)) + ; + + vb->cmd_id_active = cpu_to_virtio32(vb->vdev, vb->cmd_id_received); + sg_init_one(&sg, &vb->cmd_id_active, sizeof(vb->cmd_id_active)); + err = virtqueue_add_outbuf(vq, &sg, 1, &vb->cmd_id_active, GFP_KERNEL); + if (!err) + virtqueue_kick(vq); + return err; +} + +static int send_cmd_id_stop(struct virtio_balloon *vb) +{ + struct scatterlist sg; + struct virtqueue *vq = vb->free_page_vq; + int err, unused; + + /* Detach all the used buffers from the vq */ + while (virtqueue_get_buf(vq, &unused)) + ; + + sg_init_one(&sg, &vb->cmd_id_stop, sizeof(vb->cmd_id_stop)); + err = virtqueue_add_outbuf(vq, &sg, 1, &vb->cmd_id_stop, GFP_KERNEL); + if (!err) + virtqueue_kick(vq); + return err; +} + +static int get_free_page_and_send(struct virtio_balloon *vb) +{ + struct virtqueue *vq = vb->free_page_vq; + struct page *page; + struct scatterlist sg; + int err, unused; + void *p; + + /* Detach all the used buffers from the vq */ + while (virtqueue_get_buf(vq, &unused)) + ; + + page = alloc_pages(VIRTIO_BALLOON_FREE_PAGE_ALLOC_FLAG, + VIRTIO_BALLOON_FREE_PAGE_ORDER); + /* + * When the allocation returns NULL, it indicates that we have got all + * the possible free pages, so return -EINTR to stop. + */ + if (!page) + return -EINTR; + + p = page_address(page); + sg_init_one(&sg, p, VIRTIO_BALLOON_FREE_PAGE_SIZE); + /* There is always 1 entry reserved for the cmd id to use. */ + if (vq->num_free > 1) { + err = virtqueue_add_inbuf(vq, &sg, 1, p, GFP_KERNEL); + if (unlikely(err)) { + free_pages((unsigned long)p, + VIRTIO_BALLOON_FREE_PAGE_ORDER); + return err; + } + virtqueue_kick(vq); + spin_lock_irq(&vb->free_page_list_lock); + balloon_page_push(&vb->free_page_list, page); + vb->num_free_page_blocks++; + spin_unlock_irq(&vb->free_page_list_lock); + } else { + /* + * The vq has no available entry to add this page block, so + * just free it. + */ + free_pages((unsigned long)p, VIRTIO_BALLOON_FREE_PAGE_ORDER); + } + return 0; } +static int send_free_pages(struct virtio_balloon *vb) +{ + int err; + u32 cmd_id_active; + + while (1) { + /* + * If a stop id or a new cmd id was just received from host, + * stop the reporting. + */ + cmd_id_active = virtio32_to_cpu(vb->vdev, vb->cmd_id_active); + if (cmd_id_active != vb->cmd_id_received) + break; + + /* + * The free page blocks are allocated and sent to host one by + * one. + */ + err = get_free_page_and_send(vb); + if (err == -EINTR) + break; + else if (unlikely(err)) + return err; + } + + return 0; +} + +static void report_free_page_func(struct work_struct *work) +{ + int err; + struct virtio_balloon *vb = container_of(work, struct virtio_balloon, + report_free_page_work); + struct device *dev = &vb->vdev->dev; + + /* Start by sending the received cmd id to host with an outbuf. */ + err = send_cmd_id_start(vb); + if (unlikely(err)) + dev_err(dev, "Failed to send a start id, err = %d\n", err); + + err = send_free_pages(vb); + if (unlikely(err)) + dev_err(dev, "Failed to send a free page, err = %d\n", err); + + /* End by sending a stop id to host with an outbuf. */ + err = send_cmd_id_stop(vb); + if (unlikely(err)) + dev_err(dev, "Failed to send a stop id, err = %d\n", err); +} + #ifdef CONFIG_BALLOON_COMPACTION /* * virtballoon_migratepage - perform the balloon page migration on behalf of @@ -512,14 +742,23 @@ static struct file_system_type balloon_fs = { #endif /* CONFIG_BALLOON_COMPACTION */ -static unsigned long virtio_balloon_shrinker_scan(struct shrinker *shrinker, - struct shrink_control *sc) +static unsigned long shrink_free_pages(struct virtio_balloon *vb, + unsigned long pages_to_free) { - unsigned long pages_to_free, pages_freed = 0; - struct virtio_balloon *vb = container_of(shrinker, - struct virtio_balloon, shrinker); + unsigned long blocks_to_free, blocks_freed; - pages_to_free = sc->nr_to_scan * VIRTIO_BALLOON_PAGES_PER_PAGE; + pages_to_free = round_up(pages_to_free, + 1 << VIRTIO_BALLOON_FREE_PAGE_ORDER); + blocks_to_free = pages_to_free >> VIRTIO_BALLOON_FREE_PAGE_ORDER; + blocks_freed = return_free_pages_to_mm(vb, blocks_to_free); + + return blocks_freed << VIRTIO_BALLOON_FREE_PAGE_ORDER; +} + +static unsigned long shrink_balloon_pages(struct virtio_balloon *vb, + unsigned long pages_to_free) +{ + unsigned long pages_freed = 0; /* * One invocation of leak_balloon can deflate at most @@ -527,12 +766,33 @@ static unsigned long virtio_balloon_shrinker_scan(struct shrinker *shrinker, * multiple times to deflate pages till reaching pages_to_free. */ while (vb->num_pages && pages_to_free) { + pages_freed += leak_balloon(vb, pages_to_free) / + VIRTIO_BALLOON_PAGES_PER_PAGE; pages_to_free -= pages_freed; - pages_freed += leak_balloon(vb, pages_to_free); } update_balloon_size(vb); - return pages_freed / VIRTIO_BALLOON_PAGES_PER_PAGE; + return pages_freed; +} + +static unsigned long virtio_balloon_shrinker_scan(struct shrinker *shrinker, + struct shrink_control *sc) +{ + unsigned long pages_to_free, pages_freed = 0; + struct virtio_balloon *vb = container_of(shrinker, + struct virtio_balloon, shrinker); + + pages_to_free = sc->nr_to_scan * VIRTIO_BALLOON_PAGES_PER_PAGE; + + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) + pages_freed = shrink_free_pages(vb, pages_to_free); + + if (pages_freed >= pages_to_free) + return pages_freed; + + pages_freed += shrink_balloon_pages(vb, pages_to_free - pages_freed); + + return pages_freed; } static unsigned long virtio_balloon_shrinker_count(struct shrinker *shrinker, @@ -540,8 +800,12 @@ static unsigned long virtio_balloon_shrinker_count(struct shrinker *shrinker, { struct virtio_balloon *vb = container_of(shrinker, struct virtio_balloon, shrinker); + unsigned long count; - return vb->num_pages / VIRTIO_BALLOON_PAGES_PER_PAGE; + count = vb->num_pages / VIRTIO_BALLOON_PAGES_PER_PAGE; + count += vb->num_free_page_blocks >> VIRTIO_BALLOON_FREE_PAGE_ORDER; + + return count; } static void virtio_balloon_unregister_shrinker(struct virtio_balloon *vb) @@ -604,6 +868,31 @@ static int virtballoon_probe(struct virtio_device *vdev) } vb->vb_dev_info.inode->i_mapping->a_ops = &balloon_aops; #endif + if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) { + /* + * There is always one entry reserved for cmd id, so the ring + * size needs to be at least two to report free page hints. + */ + if (virtqueue_get_vring_size(vb->free_page_vq) < 2) { + err = -ENOSPC; + goto out_del_vqs; + } + vb->balloon_wq = alloc_workqueue("balloon-wq", + WQ_FREEZABLE | WQ_CPU_INTENSIVE, 0); + if (!vb->balloon_wq) { + err = -ENOMEM; + goto out_del_vqs; + } + INIT_WORK(&vb->report_free_page_work, report_free_page_func); + vb->cmd_id_received = VIRTIO_BALLOON_CMD_ID_STOP; + vb->cmd_id_active = cpu_to_virtio32(vb->vdev, + VIRTIO_BALLOON_CMD_ID_STOP); + vb->cmd_id_stop = cpu_to_virtio32(vb->vdev, + VIRTIO_BALLOON_CMD_ID_STOP); + vb->num_free_page_blocks = 0; + spin_lock_init(&vb->free_page_list_lock); + INIT_LIST_HEAD(&vb->free_page_list); + } /* * We continue to use VIRTIO_BALLOON_F_DEFLATE_ON_OOM to decide if a * shrinker needs to be registered to relieve memory pressure. @@ -611,7 +900,7 @@ static int virtballoon_probe(struct virtio_device *vdev) if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) { err = virtio_balloon_register_shrinker(vb); if (err) - goto out_del_vqs; + goto out_del_balloon_wq; } virtio_device_ready(vdev); @@ -619,6 +908,9 @@ static int virtballoon_probe(struct virtio_device *vdev) virtballoon_changed(vdev); return 0; +out_del_balloon_wq: + if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) + destroy_workqueue(vb->balloon_wq); out_del_vqs: vdev->config->del_vqs(vdev); out_free_vb: @@ -652,6 +944,11 @@ static void virtballoon_remove(struct virtio_device *vdev) cancel_work_sync(&vb->update_balloon_size_work); cancel_work_sync(&vb->update_balloon_stats_work); + if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) { + cancel_work_sync(&vb->report_free_page_work); + destroy_workqueue(vb->balloon_wq); + } + remove_common(vb); #ifdef CONFIG_BALLOON_COMPACTION if (vb->vb_dev_info.inode) @@ -703,6 +1000,7 @@ static unsigned int features[] = { VIRTIO_BALLOON_F_MUST_TELL_HOST, VIRTIO_BALLOON_F_STATS_VQ, VIRTIO_BALLOON_F_DEFLATE_ON_OOM, + VIRTIO_BALLOON_F_FREE_PAGE_HINT, }; static struct virtio_driver virtio_balloon_driver = { diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h index 13b8cb563892..47c9eb401c08 100644 --- a/include/uapi/linux/virtio_balloon.h +++ b/include/uapi/linux/virtio_balloon.h @@ -34,15 +34,20 @@ #define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */ #define VIRTIO_BALLOON_F_STATS_VQ 1 /* Memory Stats virtqueue */ #define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 2 /* Deflate balloon on OOM */ +#define VIRTIO_BALLOON_F_FREE_PAGE_HINT 3 /* VQ to report free pages */ /* Size of a PFN in the balloon interface. */ #define VIRTIO_BALLOON_PFN_SHIFT 12 +#define VIRTIO_BALLOON_CMD_ID_STOP 0 +#define VIRTIO_BALLOON_CMD_ID_DONE 1 struct virtio_balloon_config { /* Number of pages host wants Guest to give up. */ __u32 num_pages; /* Number of pages we've actually got in balloon. */ __u32 actual; + /* Free page report command id, readonly by guest */ + __u32 free_page_report_cmd_id; }; #define VIRTIO_BALLOON_S_SWAP_IN 0 /* Amount of memory swapped in */ |