131 lines
4.6 KiB
Diff
131 lines
4.6 KiB
Diff
From 1b47b37c33ec01ae1efc527f4c97f97f93723bc4 Mon Sep 17 00:00:00 2001
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From: "Michael S. Tsirkin" <mst@redhat.com>
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Date: Thu, 25 Jul 2019 07:54:25 -0400
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Subject: [PATCH] virtio-balloon: free pbp more aggressively
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Previous patches switched to a temporary pbp but that does not go far
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enough: after device uses a buffer, guest is free to reuse it, so
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tracking the page and freeing it later is wrong.
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Free and reset the pbp after we push each element.
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Fixes: ed48c59875b6 ("virtio-balloon: Safely handle BALLOON_PAGE_SIZE < host page size")
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Cc: qemu-stable@nongnu.org #v4.0.0
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Cc: David Hildenbrand <david@redhat.com>
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Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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(cherry-picked from commit 1b47b37c33ec01ae1efc527f4c97f97f93723bc4)
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---
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hw/virtio/virtio-balloon.c | 37 ++++++++++++++++---------------------
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1 file changed, 16 insertions(+), 21 deletions(-)
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diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
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index fe9664e42c..25de154307 100644
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--- a/hw/virtio/virtio-balloon.c
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+++ b/hw/virtio/virtio-balloon.c
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@@ -41,22 +41,19 @@ typedef struct PartiallyBalloonedPage {
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static void virtio_balloon_pbp_free(PartiallyBalloonedPage *pbp)
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{
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- if (!pbp) {
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+ if (!pbp->bitmap) {
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return;
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}
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g_free(pbp->bitmap);
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- g_free(pbp);
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+ pbp->bitmap = NULL;
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}
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-static PartiallyBalloonedPage *virtio_balloon_pbp_alloc(ram_addr_t base_gpa,
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- long subpages)
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+static void virtio_balloon_pbp_alloc(PartiallyBalloonedPage *pbp,
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+ ram_addr_t base_gpa,
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+ long subpages)
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{
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- PartiallyBalloonedPage *pbp = g_new0(PartiallyBalloonedPage, 1);
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-
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pbp->base_gpa = base_gpa;
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pbp->bitmap = bitmap_new(subpages);
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-
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- return pbp;
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}
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static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
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@@ -67,7 +64,7 @@ static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
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static void balloon_inflate_page(VirtIOBalloon *balloon,
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MemoryRegion *mr, hwaddr mr_offset,
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- PartiallyBalloonedPage **pbp)
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+ PartiallyBalloonedPage *pbp)
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{
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void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
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ram_addr_t rb_offset, rb_aligned_offset, base_gpa;
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@@ -104,22 +101,21 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
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base_gpa = memory_region_get_ram_addr(mr) + mr_offset -
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(rb_offset - rb_aligned_offset);
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- if (*pbp && !virtio_balloon_pbp_matches(*pbp, base_gpa)) {
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+ if (pbp->bitmap && !virtio_balloon_pbp_matches(pbp, base_gpa)) {
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/* We've partially ballooned part of a host page, but now
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* we're trying to balloon part of a different one. Too hard,
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* give up on the old partial page */
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- virtio_balloon_pbp_free(*pbp);
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- *pbp = NULL;
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+ virtio_balloon_pbp_free(pbp);
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}
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- if (!*pbp) {
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- *pbp = virtio_balloon_pbp_alloc(base_gpa, subpages);
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+ if (!pbp->bitmap) {
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+ virtio_balloon_pbp_alloc(pbp, base_gpa, subpages);
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}
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set_bit((rb_offset - rb_aligned_offset) / BALLOON_PAGE_SIZE,
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- (*pbp)->bitmap);
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+ pbp->bitmap);
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- if (bitmap_full((*pbp)->bitmap, subpages)) {
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+ if (bitmap_full(pbp->bitmap, subpages)) {
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/* We've accumulated a full host page, we can actually discard
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* it now */
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@@ -127,8 +123,7 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
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/* We ignore errors from ram_block_discard_range(), because it
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* has already reported them, and failing to discard a balloon
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* page is not fatal */
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- virtio_balloon_pbp_free(*pbp);
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- *pbp = NULL;
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+ virtio_balloon_pbp_free(pbp);
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}
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}
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@@ -328,13 +323,14 @@ static void balloon_stats_set_poll_interval(Object *obj, Visitor *v,
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static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
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{
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VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
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- PartiallyBalloonedPage *pbp = NULL;
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VirtQueueElement *elem;
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MemoryRegionSection section;
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for (;;) {
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+ PartiallyBalloonedPage pbp = {};
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size_t offset = 0;
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uint32_t pfn;
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+
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elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
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if (!elem) {
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break;
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@@ -379,9 +375,8 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
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virtqueue_push(vq, elem, offset);
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virtio_notify(vdev, vq);
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g_free(elem);
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+ virtio_balloon_pbp_free(&pbp);
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}
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-
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- virtio_balloon_pbp_free(pbp);
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}
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static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)
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--
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2.19.1
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