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1171 lines
33 KiB
1171 lines
33 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Virtio balloon implementation, inspired by Dor Laor and Marcelo |
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* Tosatti's implementations. |
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* |
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* Copyright 2008 Rusty Russell IBM Corporation |
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*/ |
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|
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#include <linux/virtio.h> |
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#include <linux/virtio_balloon.h> |
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#include <linux/swap.h> |
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#include <linux/workqueue.h> |
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#include <linux/delay.h> |
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#include <linux/slab.h> |
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#include <linux/module.h> |
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#include <linux/balloon_compaction.h> |
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#include <linux/oom.h> |
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#include <linux/wait.h> |
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#include <linux/mm.h> |
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#include <linux/mount.h> |
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#include <linux/magic.h> |
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#include <linux/pseudo_fs.h> |
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#include <linux/page_reporting.h> |
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|
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/* |
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* Balloon device works in 4K page units. So each page is pointed to by |
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* multiple balloon pages. All memory counters in this driver are in balloon |
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* page units. |
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*/ |
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#define VIRTIO_BALLOON_PAGES_PER_PAGE (unsigned)(PAGE_SIZE >> VIRTIO_BALLOON_PFN_SHIFT) |
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#define VIRTIO_BALLOON_ARRAY_PFNS_MAX 256 |
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/* Maximum number of (4k) pages to deflate on OOM notifications. */ |
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#define VIRTIO_BALLOON_OOM_NR_PAGES 256 |
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#define VIRTIO_BALLOON_OOM_NOTIFY_PRIORITY 80 |
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|
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#define VIRTIO_BALLOON_FREE_PAGE_ALLOC_FLAG (__GFP_NORETRY | __GFP_NOWARN | \ |
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__GFP_NOMEMALLOC) |
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/* The order of free page blocks to report to host */ |
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#define VIRTIO_BALLOON_HINT_BLOCK_ORDER (MAX_ORDER - 1) |
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/* The size of a free page block in bytes */ |
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#define VIRTIO_BALLOON_HINT_BLOCK_BYTES \ |
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(1 << (VIRTIO_BALLOON_HINT_BLOCK_ORDER + PAGE_SHIFT)) |
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#define VIRTIO_BALLOON_HINT_BLOCK_PAGES (1 << VIRTIO_BALLOON_HINT_BLOCK_ORDER) |
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|
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#ifdef CONFIG_BALLOON_COMPACTION |
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static struct vfsmount *balloon_mnt; |
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#endif |
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enum virtio_balloon_vq { |
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VIRTIO_BALLOON_VQ_INFLATE, |
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VIRTIO_BALLOON_VQ_DEFLATE, |
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VIRTIO_BALLOON_VQ_STATS, |
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VIRTIO_BALLOON_VQ_FREE_PAGE, |
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VIRTIO_BALLOON_VQ_REPORTING, |
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VIRTIO_BALLOON_VQ_MAX |
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}; |
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|
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enum virtio_balloon_config_read { |
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VIRTIO_BALLOON_CONFIG_READ_CMD_ID = 0, |
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}; |
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struct virtio_balloon { |
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struct virtio_device *vdev; |
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struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq; |
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|
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/* Balloon's own wq for cpu-intensive work items */ |
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struct workqueue_struct *balloon_wq; |
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/* The free page reporting work item submitted to the balloon wq */ |
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struct work_struct report_free_page_work; |
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|
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/* The balloon servicing is delegated to a freezable workqueue. */ |
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struct work_struct update_balloon_stats_work; |
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struct work_struct update_balloon_size_work; |
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|
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/* Prevent updating balloon when it is being canceled. */ |
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spinlock_t stop_update_lock; |
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bool stop_update; |
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/* Bitmap to indicate if reading the related config fields are needed */ |
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unsigned long config_read_bitmap; |
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|
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/* The list of allocated free pages, waiting to be given back to mm */ |
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struct list_head free_page_list; |
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spinlock_t free_page_list_lock; |
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/* The number of free page blocks on the above list */ |
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unsigned long num_free_page_blocks; |
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/* |
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* The cmd id received from host. |
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* Read it via virtio_balloon_cmd_id_received to get the latest value |
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* sent from host. |
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*/ |
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u32 cmd_id_received_cache; |
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/* The cmd id that is actively in use */ |
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__virtio32 cmd_id_active; |
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/* Buffer to store the stop sign */ |
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__virtio32 cmd_id_stop; |
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|
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/* Waiting for host to ack the pages we released. */ |
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wait_queue_head_t acked; |
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|
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/* Number of balloon pages we've told the Host we're not using. */ |
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unsigned int num_pages; |
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/* |
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* The pages we've told the Host we're not using are enqueued |
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* at vb_dev_info->pages list. |
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* Each page on this list adds VIRTIO_BALLOON_PAGES_PER_PAGE |
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* to num_pages above. |
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*/ |
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struct balloon_dev_info vb_dev_info; |
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|
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/* Synchronize access/update to this struct virtio_balloon elements */ |
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struct mutex balloon_lock; |
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|
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/* The array of pfns we tell the Host about. */ |
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unsigned int num_pfns; |
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__virtio32 pfns[VIRTIO_BALLOON_ARRAY_PFNS_MAX]; |
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|
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/* Memory statistics */ |
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struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR]; |
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|
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/* Shrinker to return free pages - VIRTIO_BALLOON_F_FREE_PAGE_HINT */ |
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struct shrinker shrinker; |
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/* OOM notifier to deflate on OOM - VIRTIO_BALLOON_F_DEFLATE_ON_OOM */ |
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struct notifier_block oom_nb; |
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|
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/* Free page reporting device */ |
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struct virtqueue *reporting_vq; |
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struct page_reporting_dev_info pr_dev_info; |
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}; |
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static const struct virtio_device_id id_table[] = { |
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{ VIRTIO_ID_BALLOON, VIRTIO_DEV_ANY_ID }, |
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{ 0 }, |
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}; |
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static u32 page_to_balloon_pfn(struct page *page) |
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{ |
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unsigned long pfn = page_to_pfn(page); |
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BUILD_BUG_ON(PAGE_SHIFT < VIRTIO_BALLOON_PFN_SHIFT); |
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/* Convert pfn from Linux page size to balloon page size. */ |
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return pfn * VIRTIO_BALLOON_PAGES_PER_PAGE; |
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} |
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static void balloon_ack(struct virtqueue *vq) |
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{ |
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struct virtio_balloon *vb = vq->vdev->priv; |
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|
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wake_up(&vb->acked); |
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} |
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static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq) |
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{ |
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struct scatterlist sg; |
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unsigned int len; |
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sg_init_one(&sg, vb->pfns, sizeof(vb->pfns[0]) * vb->num_pfns); |
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/* We should always be able to add one buffer to an empty queue. */ |
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virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL); |
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virtqueue_kick(vq); |
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/* When host has read buffer, this completes via balloon_ack */ |
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wait_event(vb->acked, virtqueue_get_buf(vq, &len)); |
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} |
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static int virtballoon_free_page_report(struct page_reporting_dev_info *pr_dev_info, |
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struct scatterlist *sg, unsigned int nents) |
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{ |
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struct virtio_balloon *vb = |
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container_of(pr_dev_info, struct virtio_balloon, pr_dev_info); |
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struct virtqueue *vq = vb->reporting_vq; |
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unsigned int unused, err; |
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/* We should always be able to add these buffers to an empty queue. */ |
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err = virtqueue_add_inbuf(vq, sg, nents, vb, GFP_NOWAIT | __GFP_NOWARN); |
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/* |
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* In the extremely unlikely case that something has occurred and we |
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* are able to trigger an error we will simply display a warning |
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* and exit without actually processing the pages. |
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*/ |
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if (WARN_ON_ONCE(err)) |
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return err; |
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virtqueue_kick(vq); |
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/* When host has read buffer, this completes via balloon_ack */ |
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wait_event(vb->acked, virtqueue_get_buf(vq, &unused)); |
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return 0; |
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} |
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static void set_page_pfns(struct virtio_balloon *vb, |
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__virtio32 pfns[], struct page *page) |
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{ |
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unsigned int i; |
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BUILD_BUG_ON(VIRTIO_BALLOON_PAGES_PER_PAGE > VIRTIO_BALLOON_ARRAY_PFNS_MAX); |
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/* |
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* Set balloon pfns pointing at this page. |
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* Note that the first pfn points at start of the page. |
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*/ |
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for (i = 0; i < VIRTIO_BALLOON_PAGES_PER_PAGE; i++) |
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pfns[i] = cpu_to_virtio32(vb->vdev, |
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page_to_balloon_pfn(page) + i); |
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} |
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static unsigned fill_balloon(struct virtio_balloon *vb, size_t num) |
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{ |
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unsigned num_allocated_pages; |
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unsigned num_pfns; |
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struct page *page; |
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LIST_HEAD(pages); |
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/* We can only do one array worth at a time. */ |
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num = min(num, ARRAY_SIZE(vb->pfns)); |
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for (num_pfns = 0; num_pfns < num; |
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num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) { |
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struct page *page = balloon_page_alloc(); |
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|
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if (!page) { |
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dev_info_ratelimited(&vb->vdev->dev, |
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"Out of puff! Can't get %u pages\n", |
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VIRTIO_BALLOON_PAGES_PER_PAGE); |
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/* Sleep for at least 1/5 of a second before retry. */ |
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msleep(200); |
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break; |
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} |
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balloon_page_push(&pages, page); |
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} |
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mutex_lock(&vb->balloon_lock); |
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vb->num_pfns = 0; |
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while ((page = balloon_page_pop(&pages))) { |
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balloon_page_enqueue(&vb->vb_dev_info, page); |
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set_page_pfns(vb, vb->pfns + vb->num_pfns, page); |
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vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE; |
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if (!virtio_has_feature(vb->vdev, |
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VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) |
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adjust_managed_page_count(page, -1); |
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vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE; |
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} |
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num_allocated_pages = vb->num_pfns; |
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/* Did we get any? */ |
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if (vb->num_pfns != 0) |
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tell_host(vb, vb->inflate_vq); |
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mutex_unlock(&vb->balloon_lock); |
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return num_allocated_pages; |
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} |
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static void release_pages_balloon(struct virtio_balloon *vb, |
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struct list_head *pages) |
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{ |
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struct page *page, *next; |
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list_for_each_entry_safe(page, next, pages, lru) { |
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if (!virtio_has_feature(vb->vdev, |
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VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) |
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adjust_managed_page_count(page, 1); |
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list_del(&page->lru); |
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put_page(page); /* balloon reference */ |
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} |
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} |
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static unsigned leak_balloon(struct virtio_balloon *vb, size_t num) |
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{ |
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unsigned num_freed_pages; |
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struct page *page; |
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struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; |
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LIST_HEAD(pages); |
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/* We can only do one array worth at a time. */ |
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num = min(num, ARRAY_SIZE(vb->pfns)); |
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mutex_lock(&vb->balloon_lock); |
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/* We can't release more pages than taken */ |
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num = min(num, (size_t)vb->num_pages); |
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for (vb->num_pfns = 0; vb->num_pfns < num; |
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vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) { |
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page = balloon_page_dequeue(vb_dev_info); |
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if (!page) |
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break; |
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set_page_pfns(vb, vb->pfns + vb->num_pfns, page); |
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list_add(&page->lru, &pages); |
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vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE; |
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} |
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num_freed_pages = vb->num_pfns; |
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/* |
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* Note that if |
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* virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST); |
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* is true, we *have* to do it in this order |
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*/ |
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if (vb->num_pfns != 0) |
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tell_host(vb, vb->deflate_vq); |
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release_pages_balloon(vb, &pages); |
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mutex_unlock(&vb->balloon_lock); |
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return num_freed_pages; |
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} |
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static inline void update_stat(struct virtio_balloon *vb, int idx, |
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u16 tag, u64 val) |
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{ |
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BUG_ON(idx >= VIRTIO_BALLOON_S_NR); |
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vb->stats[idx].tag = cpu_to_virtio16(vb->vdev, tag); |
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vb->stats[idx].val = cpu_to_virtio64(vb->vdev, val); |
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} |
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#define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT) |
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static unsigned int update_balloon_stats(struct virtio_balloon *vb) |
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{ |
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unsigned long events[NR_VM_EVENT_ITEMS]; |
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struct sysinfo i; |
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unsigned int idx = 0; |
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long available; |
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unsigned long caches; |
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all_vm_events(events); |
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si_meminfo(&i); |
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available = si_mem_available(); |
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caches = global_node_page_state(NR_FILE_PAGES); |
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#ifdef CONFIG_VM_EVENT_COUNTERS |
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update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN, |
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pages_to_bytes(events[PSWPIN])); |
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update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT, |
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pages_to_bytes(events[PSWPOUT])); |
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update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]); |
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update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]); |
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#ifdef CONFIG_HUGETLB_PAGE |
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update_stat(vb, idx++, VIRTIO_BALLOON_S_HTLB_PGALLOC, |
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events[HTLB_BUDDY_PGALLOC]); |
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update_stat(vb, idx++, VIRTIO_BALLOON_S_HTLB_PGFAIL, |
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events[HTLB_BUDDY_PGALLOC_FAIL]); |
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#endif |
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#endif |
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update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE, |
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pages_to_bytes(i.freeram)); |
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update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT, |
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pages_to_bytes(i.totalram)); |
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update_stat(vb, idx++, VIRTIO_BALLOON_S_AVAIL, |
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pages_to_bytes(available)); |
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update_stat(vb, idx++, VIRTIO_BALLOON_S_CACHES, |
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pages_to_bytes(caches)); |
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return idx; |
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} |
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/* |
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* While most virtqueues communicate guest-initiated requests to the hypervisor, |
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* the stats queue operates in reverse. The driver initializes the virtqueue |
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* with a single buffer. From that point forward, all conversations consist of |
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* a hypervisor request (a call to this function) which directs us to refill |
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* the virtqueue with a fresh stats buffer. Since stats collection can sleep, |
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* we delegate the job to a freezable workqueue that will do the actual work via |
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* stats_handle_request(). |
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*/ |
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static void stats_request(struct virtqueue *vq) |
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{ |
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struct virtio_balloon *vb = vq->vdev->priv; |
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|
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spin_lock(&vb->stop_update_lock); |
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if (!vb->stop_update) |
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queue_work(system_freezable_wq, &vb->update_balloon_stats_work); |
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spin_unlock(&vb->stop_update_lock); |
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} |
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static void stats_handle_request(struct virtio_balloon *vb) |
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{ |
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struct virtqueue *vq; |
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struct scatterlist sg; |
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unsigned int len, num_stats; |
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num_stats = update_balloon_stats(vb); |
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vq = vb->stats_vq; |
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if (!virtqueue_get_buf(vq, &len)) |
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return; |
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sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats); |
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virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL); |
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virtqueue_kick(vq); |
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} |
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|
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static inline s64 towards_target(struct virtio_balloon *vb) |
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{ |
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s64 target; |
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u32 num_pages; |
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|
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/* Legacy balloon config space is LE, unlike all other devices. */ |
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virtio_cread_le(vb->vdev, struct virtio_balloon_config, num_pages, |
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&num_pages); |
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target = num_pages; |
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return target - vb->num_pages; |
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} |
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|
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/* Gives back @num_to_return blocks of free pages to mm. */ |
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static unsigned long return_free_pages_to_mm(struct virtio_balloon *vb, |
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unsigned long num_to_return) |
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{ |
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struct page *page; |
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unsigned long num_returned; |
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|
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spin_lock_irq(&vb->free_page_list_lock); |
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for (num_returned = 0; num_returned < num_to_return; num_returned++) { |
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page = balloon_page_pop(&vb->free_page_list); |
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if (!page) |
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break; |
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free_pages((unsigned long)page_address(page), |
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VIRTIO_BALLOON_HINT_BLOCK_ORDER); |
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} |
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vb->num_free_page_blocks -= num_returned; |
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spin_unlock_irq(&vb->free_page_list_lock); |
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|
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return num_returned; |
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} |
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|
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static void virtio_balloon_queue_free_page_work(struct virtio_balloon *vb) |
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{ |
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if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) |
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return; |
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|
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/* No need to queue the work if the bit was already set. */ |
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if (test_and_set_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID, |
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&vb->config_read_bitmap)) |
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return; |
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|
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queue_work(vb->balloon_wq, &vb->report_free_page_work); |
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} |
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|
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static void virtballoon_changed(struct virtio_device *vdev) |
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{ |
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struct virtio_balloon *vb = vdev->priv; |
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unsigned long flags; |
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|
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spin_lock_irqsave(&vb->stop_update_lock, flags); |
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if (!vb->stop_update) { |
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queue_work(system_freezable_wq, |
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&vb->update_balloon_size_work); |
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virtio_balloon_queue_free_page_work(vb); |
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} |
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spin_unlock_irqrestore(&vb->stop_update_lock, flags); |
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} |
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|
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static void update_balloon_size(struct virtio_balloon *vb) |
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{ |
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u32 actual = vb->num_pages; |
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|
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/* Legacy balloon config space is LE, unlike all other devices. */ |
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virtio_cwrite_le(vb->vdev, struct virtio_balloon_config, actual, |
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&actual); |
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} |
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|
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static void update_balloon_stats_func(struct work_struct *work) |
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{ |
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struct virtio_balloon *vb; |
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|
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vb = container_of(work, struct virtio_balloon, |
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update_balloon_stats_work); |
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stats_handle_request(vb); |
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} |
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|
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static void update_balloon_size_func(struct work_struct *work) |
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{ |
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struct virtio_balloon *vb; |
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s64 diff; |
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|
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vb = container_of(work, struct virtio_balloon, |
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update_balloon_size_work); |
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diff = towards_target(vb); |
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|
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if (!diff) |
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return; |
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|
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if (diff > 0) |
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diff -= fill_balloon(vb, diff); |
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else |
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diff += leak_balloon(vb, -diff); |
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update_balloon_size(vb); |
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|
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if (diff) |
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queue_work(system_freezable_wq, work); |
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} |
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|
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static int init_vqs(struct virtio_balloon *vb) |
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{ |
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struct virtqueue *vqs[VIRTIO_BALLOON_VQ_MAX]; |
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vq_callback_t *callbacks[VIRTIO_BALLOON_VQ_MAX]; |
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const char *names[VIRTIO_BALLOON_VQ_MAX]; |
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int err; |
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|
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/* |
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* Inflateq and deflateq are used unconditionally. The names[] |
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* will be NULL if the related feature is not enabled, which will |
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* cause no allocation for the corresponding virtqueue in find_vqs. |
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*/ |
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callbacks[VIRTIO_BALLOON_VQ_INFLATE] = balloon_ack; |
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names[VIRTIO_BALLOON_VQ_INFLATE] = "inflate"; |
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callbacks[VIRTIO_BALLOON_VQ_DEFLATE] = balloon_ack; |
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names[VIRTIO_BALLOON_VQ_DEFLATE] = "deflate"; |
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callbacks[VIRTIO_BALLOON_VQ_STATS] = NULL; |
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names[VIRTIO_BALLOON_VQ_STATS] = NULL; |
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callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; |
|
names[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; |
|
names[VIRTIO_BALLOON_VQ_REPORTING] = 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; |
|
} |
|
|
|
if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) { |
|
names[VIRTIO_BALLOON_VQ_REPORTING] = "reporting_vq"; |
|
callbacks[VIRTIO_BALLOON_VQ_REPORTING] = balloon_ack; |
|
} |
|
|
|
err = virtio_find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX, vqs, |
|
callbacks, names, NULL); |
|
if (err) |
|
return err; |
|
|
|
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[VIRTIO_BALLOON_VQ_STATS]; |
|
|
|
/* |
|
* Prime this virtqueue with one buffer so the hypervisor can |
|
* use it to signal us later (it can't be broken yet!). |
|
*/ |
|
num_stats = update_balloon_stats(vb); |
|
|
|
sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats); |
|
err = virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb, |
|
GFP_KERNEL); |
|
if (err) { |
|
dev_warn(&vb->vdev->dev, "%s: add stat_vq failed\n", |
|
__func__); |
|
return err; |
|
} |
|
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]; |
|
|
|
if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) |
|
vb->reporting_vq = vqs[VIRTIO_BALLOON_VQ_REPORTING]; |
|
|
|
return 0; |
|
} |
|
|
|
static u32 virtio_balloon_cmd_id_received(struct virtio_balloon *vb) |
|
{ |
|
if (test_and_clear_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID, |
|
&vb->config_read_bitmap)) { |
|
/* Legacy balloon config space is LE, unlike all other devices. */ |
|
virtio_cread_le(vb->vdev, struct virtio_balloon_config, |
|
free_page_hint_cmd_id, |
|
&vb->cmd_id_received_cache); |
|
} |
|
|
|
return vb->cmd_id_received_cache; |
|
} |
|
|
|
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, |
|
virtio_balloon_cmd_id_received(vb)); |
|
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_HINT_BLOCK_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_HINT_BLOCK_BYTES); |
|
/* 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_HINT_BLOCK_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_HINT_BLOCK_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 (unlikely(cmd_id_active != |
|
virtio_balloon_cmd_id_received(vb))) |
|
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 virtio_balloon_report_free_page(struct virtio_balloon *vb) |
|
{ |
|
int err; |
|
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); |
|
} |
|
|
|
static void report_free_page_func(struct work_struct *work) |
|
{ |
|
struct virtio_balloon *vb = container_of(work, struct virtio_balloon, |
|
report_free_page_work); |
|
u32 cmd_id_received; |
|
|
|
cmd_id_received = virtio_balloon_cmd_id_received(vb); |
|
if (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 (cmd_id_received != VIRTIO_BALLOON_CMD_ID_STOP && |
|
cmd_id_received != |
|
virtio32_to_cpu(vb->vdev, vb->cmd_id_active)) { |
|
virtio_balloon_report_free_page(vb); |
|
} |
|
} |
|
|
|
#ifdef CONFIG_BALLOON_COMPACTION |
|
/* |
|
* virtballoon_migratepage - perform the balloon page migration on behalf of |
|
* a compaction 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 */ |
|
|
|
/* |
|
* When we migrate a page to a different zone and adjusted the |
|
* managed page count when inflating, we have to fixup the count of |
|
* both involved zones. |
|
*/ |
|
if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM) && |
|
page_zone(page) != page_zone(newpage)) { |
|
adjust_managed_page_count(page, 1); |
|
adjust_managed_page_count(newpage, -1); |
|
} |
|
|
|
/* 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, vb->pfns, newpage); |
|
tell_host(vb, vb->inflate_vq); |
|
|
|
/* balloon's page migration 2nd step -- deflate "page" */ |
|
spin_lock_irqsave(&vb_dev_info->pages_lock, flags); |
|
balloon_page_delete(page); |
|
spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags); |
|
vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE; |
|
set_page_pfns(vb, vb->pfns, page); |
|
tell_host(vb, vb->deflate_vq); |
|
|
|
mutex_unlock(&vb->balloon_lock); |
|
|
|
put_page(page); /* balloon reference */ |
|
|
|
return MIGRATEPAGE_SUCCESS; |
|
} |
|
|
|
static int balloon_init_fs_context(struct fs_context *fc) |
|
{ |
|
return init_pseudo(fc, BALLOON_KVM_MAGIC) ? 0 : -ENOMEM; |
|
} |
|
|
|
static struct file_system_type balloon_fs = { |
|
.name = "balloon-kvm", |
|
.init_fs_context = balloon_init_fs_context, |
|
.kill_sb = kill_anon_super, |
|
}; |
|
|
|
#endif /* CONFIG_BALLOON_COMPACTION */ |
|
|
|
static unsigned long shrink_free_pages(struct virtio_balloon *vb, |
|
unsigned long pages_to_free) |
|
{ |
|
unsigned long blocks_to_free, blocks_freed; |
|
|
|
pages_to_free = round_up(pages_to_free, |
|
VIRTIO_BALLOON_HINT_BLOCK_PAGES); |
|
blocks_to_free = pages_to_free / VIRTIO_BALLOON_HINT_BLOCK_PAGES; |
|
blocks_freed = return_free_pages_to_mm(vb, blocks_to_free); |
|
|
|
return blocks_freed * VIRTIO_BALLOON_HINT_BLOCK_PAGES; |
|
} |
|
|
|
static unsigned long virtio_balloon_shrinker_scan(struct shrinker *shrinker, |
|
struct shrink_control *sc) |
|
{ |
|
struct virtio_balloon *vb = container_of(shrinker, |
|
struct virtio_balloon, shrinker); |
|
|
|
return shrink_free_pages(vb, sc->nr_to_scan); |
|
} |
|
|
|
static unsigned long virtio_balloon_shrinker_count(struct shrinker *shrinker, |
|
struct shrink_control *sc) |
|
{ |
|
struct virtio_balloon *vb = container_of(shrinker, |
|
struct virtio_balloon, shrinker); |
|
|
|
return vb->num_free_page_blocks * VIRTIO_BALLOON_HINT_BLOCK_PAGES; |
|
} |
|
|
|
static int virtio_balloon_oom_notify(struct notifier_block *nb, |
|
unsigned long dummy, void *parm) |
|
{ |
|
struct virtio_balloon *vb = container_of(nb, |
|
struct virtio_balloon, oom_nb); |
|
unsigned long *freed = parm; |
|
|
|
*freed += leak_balloon(vb, VIRTIO_BALLOON_OOM_NR_PAGES) / |
|
VIRTIO_BALLOON_PAGES_PER_PAGE; |
|
update_balloon_size(vb); |
|
|
|
return NOTIFY_OK; |
|
} |
|
|
|
static void virtio_balloon_unregister_shrinker(struct virtio_balloon *vb) |
|
{ |
|
unregister_shrinker(&vb->shrinker); |
|
} |
|
|
|
static int virtio_balloon_register_shrinker(struct virtio_balloon *vb) |
|
{ |
|
vb->shrinker.scan_objects = virtio_balloon_shrinker_scan; |
|
vb->shrinker.count_objects = virtio_balloon_shrinker_count; |
|
vb->shrinker.seeks = DEFAULT_SEEKS; |
|
|
|
return register_shrinker(&vb->shrinker); |
|
} |
|
|
|
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 = kzalloc(sizeof(*vb), GFP_KERNEL); |
|
if (!vb) { |
|
err = -ENOMEM; |
|
goto out; |
|
} |
|
|
|
INIT_WORK(&vb->update_balloon_stats_work, update_balloon_stats_func); |
|
INIT_WORK(&vb->update_balloon_size_work, update_balloon_size_func); |
|
spin_lock_init(&vb->stop_update_lock); |
|
mutex_init(&vb->balloon_lock); |
|
init_waitqueue_head(&vb->acked); |
|
vb->vdev = vdev; |
|
|
|
balloon_devinfo_init(&vb->vb_dev_info); |
|
|
|
err = init_vqs(vb); |
|
if (err) |
|
goto out_free_vb; |
|
|
|
#ifdef CONFIG_BALLOON_COMPACTION |
|
balloon_mnt = kern_mount(&balloon_fs); |
|
if (IS_ERR(balloon_mnt)) { |
|
err = PTR_ERR(balloon_mnt); |
|
goto out_del_vqs; |
|
} |
|
|
|
vb->vb_dev_info.migratepage = virtballoon_migratepage; |
|
vb->vb_dev_info.inode = alloc_anon_inode(balloon_mnt->mnt_sb); |
|
if (IS_ERR(vb->vb_dev_info.inode)) { |
|
err = PTR_ERR(vb->vb_dev_info.inode); |
|
goto out_kern_unmount; |
|
} |
|
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_iput; |
|
} |
|
vb->balloon_wq = alloc_workqueue("balloon-wq", |
|
WQ_FREEZABLE | WQ_CPU_INTENSIVE, 0); |
|
if (!vb->balloon_wq) { |
|
err = -ENOMEM; |
|
goto out_iput; |
|
} |
|
INIT_WORK(&vb->report_free_page_work, report_free_page_func); |
|
vb->cmd_id_received_cache = 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); |
|
spin_lock_init(&vb->free_page_list_lock); |
|
INIT_LIST_HEAD(&vb->free_page_list); |
|
/* |
|
* We're allowed to reuse any free pages, even if they are |
|
* still to be processed by the host. |
|
*/ |
|
err = virtio_balloon_register_shrinker(vb); |
|
if (err) |
|
goto out_del_balloon_wq; |
|
} |
|
|
|
if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) { |
|
vb->oom_nb.notifier_call = virtio_balloon_oom_notify; |
|
vb->oom_nb.priority = VIRTIO_BALLOON_OOM_NOTIFY_PRIORITY; |
|
err = register_oom_notifier(&vb->oom_nb); |
|
if (err < 0) |
|
goto out_unregister_shrinker; |
|
} |
|
|
|
if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) { |
|
/* Start with poison val of 0 representing general init */ |
|
__u32 poison_val = 0; |
|
|
|
/* |
|
* Let the hypervisor know that we are expecting a |
|
* specific value to be written back in balloon pages. |
|
* |
|
* If the PAGE_POISON value was larger than a byte we would |
|
* need to byte swap poison_val here to guarantee it is |
|
* little-endian. However for now it is a single byte so we |
|
* can pass it as-is. |
|
*/ |
|
if (!want_init_on_free()) |
|
memset(&poison_val, PAGE_POISON, sizeof(poison_val)); |
|
|
|
virtio_cwrite_le(vb->vdev, struct virtio_balloon_config, |
|
poison_val, &poison_val); |
|
} |
|
|
|
vb->pr_dev_info.report = virtballoon_free_page_report; |
|
if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) { |
|
unsigned int capacity; |
|
|
|
capacity = virtqueue_get_vring_size(vb->reporting_vq); |
|
if (capacity < PAGE_REPORTING_CAPACITY) { |
|
err = -ENOSPC; |
|
goto out_unregister_oom; |
|
} |
|
|
|
/* |
|
* The default page reporting order is @pageblock_order, which |
|
* corresponds to 512MB in size on ARM64 when 64KB base page |
|
* size is used. The page reporting won't be triggered if the |
|
* freeing page can't come up with a free area like that huge. |
|
* So we specify the page reporting order to 5, corresponding |
|
* to 2MB. It helps to avoid THP splitting if 4KB base page |
|
* size is used by host. |
|
* |
|
* Ideally, the page reporting order is selected based on the |
|
* host's base page size. However, it needs more work to report |
|
* that value. The hard-coded order would be fine currently. |
|
*/ |
|
#if defined(CONFIG_ARM64) && defined(CONFIG_ARM64_64K_PAGES) |
|
vb->pr_dev_info.order = 5; |
|
#endif |
|
|
|
err = page_reporting_register(&vb->pr_dev_info); |
|
if (err) |
|
goto out_unregister_oom; |
|
} |
|
|
|
virtio_device_ready(vdev); |
|
|
|
if (towards_target(vb)) |
|
virtballoon_changed(vdev); |
|
return 0; |
|
|
|
out_unregister_oom: |
|
if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) |
|
unregister_oom_notifier(&vb->oom_nb); |
|
out_unregister_shrinker: |
|
if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) |
|
virtio_balloon_unregister_shrinker(vb); |
|
out_del_balloon_wq: |
|
if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) |
|
destroy_workqueue(vb->balloon_wq); |
|
out_iput: |
|
#ifdef CONFIG_BALLOON_COMPACTION |
|
iput(vb->vb_dev_info.inode); |
|
out_kern_unmount: |
|
kern_unmount(balloon_mnt); |
|
out_del_vqs: |
|
#endif |
|
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); |
|
|
|
/* There might be free pages that are being reported: release them. */ |
|
if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) |
|
return_free_pages_to_mm(vb, ULONG_MAX); |
|
|
|
/* 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; |
|
|
|
if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) |
|
page_reporting_unregister(&vb->pr_dev_info); |
|
if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) |
|
unregister_oom_notifier(&vb->oom_nb); |
|
if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) |
|
virtio_balloon_unregister_shrinker(vb); |
|
spin_lock_irq(&vb->stop_update_lock); |
|
vb->stop_update = true; |
|
spin_unlock_irq(&vb->stop_update_lock); |
|
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) |
|
iput(vb->vb_dev_info.inode); |
|
|
|
kern_unmount(balloon_mnt); |
|
#endif |
|
kfree(vb); |
|
} |
|
|
|
#ifdef CONFIG_PM_SLEEP |
|
static int virtballoon_freeze(struct virtio_device *vdev) |
|
{ |
|
struct virtio_balloon *vb = vdev->priv; |
|
|
|
/* |
|
* The workqueue 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); |
|
|
|
if (towards_target(vb)) |
|
virtballoon_changed(vdev); |
|
update_balloon_size(vb); |
|
return 0; |
|
} |
|
#endif |
|
|
|
static int virtballoon_validate(struct virtio_device *vdev) |
|
{ |
|
/* |
|
* Inform the hypervisor that our pages are poisoned or |
|
* initialized. If we cannot do that then we should disable |
|
* page reporting as it could potentially change the contents |
|
* of our free pages. |
|
*/ |
|
if (!want_init_on_free() && !page_poisoning_enabled_static()) |
|
__virtio_clear_bit(vdev, VIRTIO_BALLOON_F_PAGE_POISON); |
|
else if (!virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) |
|
__virtio_clear_bit(vdev, VIRTIO_BALLOON_F_REPORTING); |
|
|
|
__virtio_clear_bit(vdev, VIRTIO_F_ACCESS_PLATFORM); |
|
return 0; |
|
} |
|
|
|
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, |
|
VIRTIO_BALLOON_F_PAGE_POISON, |
|
VIRTIO_BALLOON_F_REPORTING, |
|
}; |
|
|
|
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, |
|
.validate = virtballoon_validate, |
|
.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");
|
|
|