@@ -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)
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> --- hw/virtio/virtio-balloon.c | 37 ++++++++++++++++--------------------- 1 file changed, 16 insertions(+), 21 deletions(-)