Message ID | 20190725151735.29334-1-mst@redhat.com |
---|---|
State | New |
Headers | show |
Series | [v4] virtio-balloon: free pbp more aggressively | expand |
On 25.07.19 17:18, Michael S. Tsirkin wrote: > 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> > --- > > changes from v2, v3: > v3 was same as v2, sent by mistake > v4 fixes a typo > > hw/virtio/virtio-balloon.c | 37 ++++++++++++++++--------------------- > > diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c > index fe9664e42c..25de154307 100644 > --- a/hw/virtio/virtio-balloon.c > +++ b/hw/virtio/virtio-balloon.c > @@ -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) > Works with hugetlbfs on x86 and LGTM: Reviewed-by: David Hildenbrand <david@redhat.com>
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c index fe9664e42c..25de154307 100644 --- a/hw/virtio/virtio-balloon.c +++ b/hw/virtio/virtio-balloon.c @@ -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> --- changes from v2, v3: v3 was same as v2, sent by mistake v4 fixes a typo hw/virtio/virtio-balloon.c | 37 ++++++++++++++++---------------------