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f7ad26ff95
checkpatch.pl wants arrays of strings declared as follows: static const char * const names[] = { "vq-1", "vq-2", "vq-3" }; Currently the find_vqs() function takes a const char *names[] argument so passing checkpatch.pl's const char * const names[] results in a compiler error due to losing the second const. This patch adjusts the find_vqs() prototype and updates all virtio transports. This makes it possible for virtio_balloon.c, virtio_input.c, virtgpu_kms.c, and virtio_rpmsg_bus.c to use the checkpatch.pl-friendly type. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Bjorn Andersson <bjorn.andersson@sonymobile.com>
623 lines
17 KiB
C
623 lines
17 KiB
C
/*
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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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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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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/kthread.h>
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#include <linux/freezer.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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/*
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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 OOM_VBALLOON_DEFAULT_PAGES 256
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#define VIRTBALLOON_OOM_NOTIFY_PRIORITY 80
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static int oom_pages = OOM_VBALLOON_DEFAULT_PAGES;
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module_param(oom_pages, int, S_IRUSR | S_IWUSR);
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MODULE_PARM_DESC(oom_pages, "pages to free on OOM");
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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;
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/* Where the ballooning thread waits for config to change. */
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wait_queue_head_t config_change;
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/* The thread servicing the balloon. */
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struct task_struct *thread;
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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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u32 pfns[VIRTIO_BALLOON_ARRAY_PFNS_MAX];
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/* Memory statistics */
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int need_stats_update;
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struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
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/* To register callback in oom notifier call chain */
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struct notifier_block nb;
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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 struct page *balloon_pfn_to_page(u32 pfn)
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{
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BUG_ON(pfn % VIRTIO_BALLOON_PAGES_PER_PAGE);
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return pfn_to_page(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(u32 pfns[], struct page *page)
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{
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unsigned int i;
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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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for (i = 0; i < VIRTIO_BALLOON_PAGES_PER_PAGE; i++)
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pfns[i] = page_to_balloon_pfn(page) + i;
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}
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static void fill_balloon(struct virtio_balloon *vb, size_t num)
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{
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struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;
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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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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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struct page *page = balloon_page_enqueue(vb_dev_info);
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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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set_page_pfns(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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}
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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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}
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static void release_pages_balloon(struct virtio_balloon *vb)
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{
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unsigned int i;
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/* Find pfns pointing at start of each page, get pages and free them. */
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for (i = 0; i < vb->num_pfns; i += VIRTIO_BALLOON_PAGES_PER_PAGE) {
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struct page *page = balloon_pfn_to_page(vb->pfns[i]);
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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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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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/* 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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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->pfns + vb->num_pfns, page);
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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);
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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 void 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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int idx = 0;
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all_vm_events(events);
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si_meminfo(&i);
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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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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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}
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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 notify our kthread which does the actual work via 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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vb->need_stats_update = 1;
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wake_up(&vb->config_change);
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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;
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vb->need_stats_update = 0;
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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));
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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 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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wake_up(&vb->config_change);
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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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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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/*
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* virtballoon_oom_notify - release pages when system is under severe
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* memory pressure (called from out_of_memory())
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* @self : notifier block struct
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* @dummy: not used
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* @parm : returned - number of freed pages
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*
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* The balancing of memory by use of the virtio balloon should not cause
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* the termination of processes while there are pages in the balloon.
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* If virtio balloon manages to release some memory, it will make the
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* system return and retry the allocation that forced the OOM killer
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* to run.
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*/
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static int virtballoon_oom_notify(struct notifier_block *self,
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unsigned long dummy, void *parm)
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{
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struct virtio_balloon *vb;
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unsigned long *freed;
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unsigned num_freed_pages;
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vb = container_of(self, struct virtio_balloon, nb);
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if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
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return NOTIFY_OK;
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freed = parm;
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num_freed_pages = leak_balloon(vb, oom_pages);
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update_balloon_size(vb);
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*freed += num_freed_pages;
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return NOTIFY_OK;
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}
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static int balloon(void *_vballoon)
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{
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struct virtio_balloon *vb = _vballoon;
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DEFINE_WAIT_FUNC(wait, woken_wake_function);
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set_freezable();
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while (!kthread_should_stop()) {
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s64 diff;
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try_to_freeze();
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add_wait_queue(&vb->config_change, &wait);
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for (;;) {
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if ((diff = towards_target(vb)) != 0 ||
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vb->need_stats_update ||
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kthread_should_stop() ||
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freezing(current))
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break;
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wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
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}
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remove_wait_queue(&vb->config_change, &wait);
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if (vb->need_stats_update)
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stats_handle_request(vb);
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if (diff > 0)
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fill_balloon(vb, diff);
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else if (diff < 0)
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leak_balloon(vb, -diff);
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update_balloon_size(vb);
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/*
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* For large balloon changes, we could spend a lot of time
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* and always have work to do. Be nice if preempt disabled.
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*/
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cond_resched();
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}
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return 0;
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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[3];
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vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request };
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static const char * const names[] = { "inflate", "deflate", "stats" };
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int err, nvqs;
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/*
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* We expect two virtqueues: inflate and deflate, and
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* optionally stat.
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*/
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nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2;
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err = vb->vdev->config->find_vqs(vb->vdev, nvqs, vqs, callbacks, names);
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if (err)
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return err;
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vb->inflate_vq = vqs[0];
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vb->deflate_vq = vqs[1];
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if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
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struct scatterlist sg;
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vb->stats_vq = vqs[2];
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/*
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* Prime this virtqueue with one buffer so the hypervisor can
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* use it to signal us later (it can't be broken yet!).
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*/
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sg_init_one(&sg, vb->stats, sizeof vb->stats);
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if (virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb, GFP_KERNEL)
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< 0)
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BUG();
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virtqueue_kick(vb->stats_vq);
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}
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return 0;
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}
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#ifdef CONFIG_BALLOON_COMPACTION
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/*
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* virtballoon_migratepage - perform the balloon page migration on behalf of
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* a compation thread. (called under page lock)
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* @vb_dev_info: the balloon device
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* @newpage: page that will replace the isolated page after migration finishes.
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* @page : the isolated (old) page that is about to be migrated to newpage.
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* @mode : compaction mode -- not used for balloon page migration.
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*
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* After a ballooned page gets isolated by compaction procedures, this is the
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* function that performs the page migration on behalf of a compaction thread
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* The page migration for virtio balloon is done in a simple swap fashion which
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* follows these two macro steps:
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* 1) insert newpage into vb->pages list and update the host about it;
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* 2) update the host about the old page removed from vb->pages list;
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*
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* This function preforms the balloon page migration task.
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* Called through balloon_mapping->a_ops->migratepage
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*/
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static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info,
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struct page *newpage, struct page *page, enum migrate_mode mode)
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{
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struct virtio_balloon *vb = container_of(vb_dev_info,
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struct virtio_balloon, vb_dev_info);
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unsigned long flags;
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/*
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* In order to avoid lock contention while migrating pages concurrently
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* to leak_balloon() or fill_balloon() we just give up the balloon_lock
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* this turn, as it is easier to retry the page migration later.
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* This also prevents fill_balloon() getting stuck into a mutex
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* recursion in the case it ends up triggering memory compaction
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* while it is attempting to inflate the ballon.
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*/
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if (!mutex_trylock(&vb->balloon_lock))
|
|
return -EAGAIN;
|
|
|
|
get_page(newpage); /* balloon reference */
|
|
|
|
/* balloon's page migration 1st step -- inflate "newpage" */
|
|
spin_lock_irqsave(&vb_dev_info->pages_lock, flags);
|
|
balloon_page_insert(vb_dev_info, newpage);
|
|
vb_dev_info->isolated_pages--;
|
|
__count_vm_event(BALLOON_MIGRATE);
|
|
spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags);
|
|
vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
|
|
set_page_pfns(vb->pfns, newpage);
|
|
tell_host(vb, vb->inflate_vq);
|
|
|
|
/* balloon's page migration 2nd step -- deflate "page" */
|
|
balloon_page_delete(page);
|
|
vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
|
|
set_page_pfns(vb->pfns, page);
|
|
tell_host(vb, vb->deflate_vq);
|
|
|
|
mutex_unlock(&vb->balloon_lock);
|
|
|
|
put_page(page); /* balloon reference */
|
|
|
|
return MIGRATEPAGE_SUCCESS;
|
|
}
|
|
#endif /* CONFIG_BALLOON_COMPACTION */
|
|
|
|
static int virtballoon_probe(struct virtio_device *vdev)
|
|
{
|
|
struct virtio_balloon *vb;
|
|
int err;
|
|
|
|
if (!vdev->config->get) {
|
|
dev_err(&vdev->dev, "%s failure: config access disabled\n",
|
|
__func__);
|
|
return -EINVAL;
|
|
}
|
|
|
|
vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL);
|
|
if (!vb) {
|
|
err = -ENOMEM;
|
|
goto out;
|
|
}
|
|
|
|
vb->num_pages = 0;
|
|
mutex_init(&vb->balloon_lock);
|
|
init_waitqueue_head(&vb->config_change);
|
|
init_waitqueue_head(&vb->acked);
|
|
vb->vdev = vdev;
|
|
vb->need_stats_update = 0;
|
|
|
|
balloon_devinfo_init(&vb->vb_dev_info);
|
|
#ifdef CONFIG_BALLOON_COMPACTION
|
|
vb->vb_dev_info.migratepage = virtballoon_migratepage;
|
|
#endif
|
|
|
|
err = init_vqs(vb);
|
|
if (err)
|
|
goto out_free_vb;
|
|
|
|
vb->nb.notifier_call = virtballoon_oom_notify;
|
|
vb->nb.priority = VIRTBALLOON_OOM_NOTIFY_PRIORITY;
|
|
err = register_oom_notifier(&vb->nb);
|
|
if (err < 0)
|
|
goto out_oom_notify;
|
|
|
|
virtio_device_ready(vdev);
|
|
|
|
vb->thread = kthread_run(balloon, vb, "vballoon");
|
|
if (IS_ERR(vb->thread)) {
|
|
err = PTR_ERR(vb->thread);
|
|
goto out_del_vqs;
|
|
}
|
|
|
|
return 0;
|
|
|
|
out_del_vqs:
|
|
unregister_oom_notifier(&vb->nb);
|
|
out_oom_notify:
|
|
vdev->config->del_vqs(vdev);
|
|
out_free_vb:
|
|
kfree(vb);
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
static void remove_common(struct virtio_balloon *vb)
|
|
{
|
|
/* There might be pages left in the balloon: free them. */
|
|
while (vb->num_pages)
|
|
leak_balloon(vb, vb->num_pages);
|
|
update_balloon_size(vb);
|
|
|
|
/* Now we reset the device so we can clean up the queues. */
|
|
vb->vdev->config->reset(vb->vdev);
|
|
|
|
vb->vdev->config->del_vqs(vb->vdev);
|
|
}
|
|
|
|
static void virtballoon_remove(struct virtio_device *vdev)
|
|
{
|
|
struct virtio_balloon *vb = vdev->priv;
|
|
|
|
unregister_oom_notifier(&vb->nb);
|
|
kthread_stop(vb->thread);
|
|
remove_common(vb);
|
|
kfree(vb);
|
|
}
|
|
|
|
#ifdef CONFIG_PM_SLEEP
|
|
static int virtballoon_freeze(struct virtio_device *vdev)
|
|
{
|
|
struct virtio_balloon *vb = vdev->priv;
|
|
|
|
/*
|
|
* The kthread is already frozen by the PM core before this
|
|
* function is called.
|
|
*/
|
|
|
|
remove_common(vb);
|
|
return 0;
|
|
}
|
|
|
|
static int virtballoon_restore(struct virtio_device *vdev)
|
|
{
|
|
struct virtio_balloon *vb = vdev->priv;
|
|
int ret;
|
|
|
|
ret = init_vqs(vdev->priv);
|
|
if (ret)
|
|
return ret;
|
|
|
|
virtio_device_ready(vdev);
|
|
|
|
fill_balloon(vb, towards_target(vb));
|
|
update_balloon_size(vb);
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
static unsigned int features[] = {
|
|
VIRTIO_BALLOON_F_MUST_TELL_HOST,
|
|
VIRTIO_BALLOON_F_STATS_VQ,
|
|
VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
|
|
};
|
|
|
|
static struct virtio_driver virtio_balloon_driver = {
|
|
.feature_table = features,
|
|
.feature_table_size = ARRAY_SIZE(features),
|
|
.driver.name = KBUILD_MODNAME,
|
|
.driver.owner = THIS_MODULE,
|
|
.id_table = id_table,
|
|
.probe = virtballoon_probe,
|
|
.remove = virtballoon_remove,
|
|
.config_changed = virtballoon_changed,
|
|
#ifdef CONFIG_PM_SLEEP
|
|
.freeze = virtballoon_freeze,
|
|
.restore = virtballoon_restore,
|
|
#endif
|
|
};
|
|
|
|
module_virtio_driver(virtio_balloon_driver);
|
|
MODULE_DEVICE_TABLE(virtio, id_table);
|
|
MODULE_DESCRIPTION("Virtio balloon driver");
|
|
MODULE_LICENSE("GPL");
|