forked from Minki/linux
63b9b80e9f
We managed to get confused about the shift direction at least once. Let's switch to division/multiplcation instead. Add a number of pages macro for this purpose. We still keep the order macro around too since this is what alloc/free pages want. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Wei Wang <wei.w.wang@intel.com> Reviewed-by: David Hildenbrand <david@redhat.com>
1070 lines
30 KiB
C
1070 lines
30 KiB
C
// 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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#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/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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/*
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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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#define VIRTBALLOON_OOM_NOTIFY_PRIORITY 80
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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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#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_MAX
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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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/* 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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/* 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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/* 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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/* 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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/* Waiting for host to ack the pages we released. */
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wait_queue_head_t acked;
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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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/* Synchronize access/update to this struct virtio_balloon elements */
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struct mutex balloon_lock;
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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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/* Memory statistics */
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struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
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/* To register a shrinker to shrink memory upon memory pressure */
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struct shrinker shrinker;
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};
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static 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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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 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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/*
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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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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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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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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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virtio_cread(vb->vdev, struct virtio_balloon_config, num_pages,
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&num_pages);
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/* Legacy balloon config space is LE, unlike all other devices. */
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if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1))
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num_pages = le32_to_cpu((__force __le32)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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/* 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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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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return num_returned;
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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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/* 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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queue_work(vb->balloon_wq, &vb->report_free_page_work);
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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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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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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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/* Legacy balloon config space is LE, unlike all other devices. */
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if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1))
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actual = (__force u32)cpu_to_le32(actual);
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virtio_cwrite(vb->vdev, struct virtio_balloon_config, actual,
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&actual);
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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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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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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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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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if (!diff)
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return;
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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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if (diff)
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queue_work(system_freezable_wq, work);
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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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|
/*
|
|
* 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.
|
|
*/
|
|
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[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];
|
|
|
|
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))
|
|
virtio_cread(vb->vdev, struct virtio_balloon_config,
|
|
free_page_report_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 = virtio32_to_cpu(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 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 */
|
|
|
|
/*
|
|
* 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 leak_balloon_pages(struct virtio_balloon *vb,
|
|
unsigned long pages_to_free)
|
|
{
|
|
return leak_balloon(vb, pages_to_free * VIRTIO_BALLOON_PAGES_PER_PAGE) /
|
|
VIRTIO_BALLOON_PAGES_PER_PAGE;
|
|
}
|
|
|
|
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
|
|
* VIRTIO_BALLOON_ARRAY_PFNS_MAX balloon pages, so we call it
|
|
* multiple times to deflate pages till reaching pages_to_free.
|
|
*/
|
|
while (vb->num_pages && pages_freed < pages_to_free)
|
|
pages_freed += leak_balloon_pages(vb,
|
|
pages_to_free - pages_freed);
|
|
|
|
update_balloon_size(vb);
|
|
|
|
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;
|
|
|
|
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,
|
|
struct shrink_control *sc)
|
|
{
|
|
struct virtio_balloon *vb = container_of(shrinker,
|
|
struct virtio_balloon, shrinker);
|
|
unsigned long count;
|
|
|
|
count = vb->num_pages / VIRTIO_BALLOON_PAGES_PER_PAGE;
|
|
count += vb->num_free_page_blocks * VIRTIO_BALLOON_HINT_BLOCK_PAGES;
|
|
|
|
return count;
|
|
}
|
|
|
|
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;
|
|
__u32 poison_val;
|
|
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);
|
|
kern_unmount(balloon_mnt);
|
|
goto out_del_vqs;
|
|
}
|
|
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_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);
|
|
if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
|
|
memset(&poison_val, PAGE_POISON, sizeof(poison_val));
|
|
virtio_cwrite(vb->vdev, struct virtio_balloon_config,
|
|
poison_val, &poison_val);
|
|
}
|
|
}
|
|
/*
|
|
* We continue to use VIRTIO_BALLOON_F_DEFLATE_ON_OOM to decide if a
|
|
* shrinker needs to be registered to relieve memory pressure.
|
|
*/
|
|
if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) {
|
|
err = virtio_balloon_register_shrinker(vb);
|
|
if (err)
|
|
goto out_del_balloon_wq;
|
|
}
|
|
virtio_device_ready(vdev);
|
|
|
|
if (towards_target(vb))
|
|
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:
|
|
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;
|
|
|
|
if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
|
|
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)
|
|
{
|
|
if (!page_poisoning_enabled())
|
|
__virtio_clear_bit(vdev, VIRTIO_BALLOON_F_PAGE_POISON);
|
|
|
|
__virtio_clear_bit(vdev, VIRTIO_F_IOMMU_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,
|
|
};
|
|
|
|
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");
|