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virtio-balloon: free pbp more aggressively

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Previous patches switched to a temporary pbp but that does not go far
enough: after device uses a buffer, guest is free to reuse it, so
tracking the page and freeing it later is wrong.

Free and reset the pbp after we push each element.

Fixes: ed48c59875b6 ("virtio-balloon: Safely handle BALLOON_PAGE_SIZE < host page size")
Cc: qemu-stable@nongnu.org #v4.0.0
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Michael S. Tsirkin 2019-07-25 07:54:25 -04:00
parent 9a7ca8a7c9
commit 1b47b37c33
1 changed files with 16 additions and 21 deletions
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37
hw/virtio/virtio-balloon.c
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@ -41,22 +41,19 @@ typedef struct PartiallyBalloonedPage {
static void virtio_balloon_pbp_free(PartiallyBalloonedPage *pbp)
{
if (!pbp) {
if (!pbp->bitmap) {
return;
}
g_free(pbp->bitmap);
g_free(pbp);
pbp->bitmap = NULL;
}
static PartiallyBalloonedPage *virtio_balloon_pbp_alloc(ram_addr_t base_gpa,
long subpages)
static void virtio_balloon_pbp_alloc(PartiallyBalloonedPage *pbp,
ram_addr_t base_gpa,
long subpages)
{
PartiallyBalloonedPage *pbp = g_new0(PartiallyBalloonedPage, 1);
pbp->base_gpa = base_gpa;
pbp->bitmap = bitmap_new(subpages);
return pbp;
}
static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
@ -67,7 +64,7 @@ static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
static void balloon_inflate_page(VirtIOBalloon *balloon,
MemoryRegion *mr, hwaddr mr_offset,
PartiallyBalloonedPage **pbp)
PartiallyBalloonedPage *pbp)
{
void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
ram_addr_t rb_offset, rb_aligned_offset, base_gpa;
@ -104,22 +101,21 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
base_gpa = memory_region_get_ram_addr(mr) + mr_offset -
(rb_offset - rb_aligned_offset);
if (*pbp && !virtio_balloon_pbp_matches(*pbp, base_gpa)) {
if (pbp->bitmap && !virtio_balloon_pbp_matches(pbp, base_gpa)) {
/* We've partially ballooned part of a host page, but now
* we're trying to balloon part of a different one. Too hard,
* give up on the old partial page */
virtio_balloon_pbp_free(*pbp);
*pbp = NULL;
virtio_balloon_pbp_free(pbp);
}
if (!*pbp) {
*pbp = virtio_balloon_pbp_alloc(base_gpa, subpages);
if (!pbp->bitmap) {
virtio_balloon_pbp_alloc(pbp, base_gpa, subpages);
}
set_bit((rb_offset - rb_aligned_offset) / BALLOON_PAGE_SIZE,
(*pbp)->bitmap);
pbp->bitmap);
if (bitmap_full((*pbp)->bitmap, subpages)) {
if (bitmap_full(pbp->bitmap, subpages)) {
/* We've accumulated a full host page, we can actually discard
* it now */
@ -127,8 +123,7 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
/* We ignore errors from ram_block_discard_range(), because it
* has already reported them, and failing to discard a balloon
* page is not fatal */
virtio_balloon_pbp_free(*pbp);
*pbp = NULL;
virtio_balloon_pbp_free(pbp);
}
}
@ -328,13 +323,14 @@ static void balloon_stats_set_poll_interval(Object *obj, Visitor *v,
static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
{
VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
PartiallyBalloonedPage *pbp = NULL;
VirtQueueElement *elem;
MemoryRegionSection section;
for (;;) {
PartiallyBalloonedPage pbp = {};
size_t offset = 0;
uint32_t pfn;
elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
if (!elem) {
break;
@ -379,9 +375,8 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
virtqueue_push(vq, elem, offset);
virtio_notify(vdev, vq);
g_free(elem);
virtio_balloon_pbp_free(&pbp);
}
virtio_balloon_pbp_free(pbp);
}
static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)