From 5c0ba1be37181bd8a7c96c7f81b19ae5f8e66e2d Mon Sep 17 00:00:00 2001 From: Felipe Franciosi Date: Wed, 20 Sep 2017 11:53:06 -0700 Subject: [PATCH] virtio/vhost: reset dev->log after syncing MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit vhost_log_put() is called to decomission the dirty log between qemu and a vhost device when stopping the device. Such a call can happen from migration_completion(). Present code sets dev->log_size to zero too early in vhost_log_put(), causing the sync check to always return false. As a consequence, the last pass on the dirty bitmap never happens at the end of migration. If a vhost device was busy (writing to guest memory) until the last moments before vhost_virtqueue_stop(), this error will result in guest memory corruption (at least) following migrations. Signed-off-by: Felipe Franciosi Acked-by: Jason Wang Reviewed-by: Marc-André Lureau Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/virtio/vhost.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c index 5fd69f0b2e..ddc42f0f93 100644 --- a/hw/virtio/vhost.c +++ b/hw/virtio/vhost.c @@ -375,8 +375,6 @@ static void vhost_log_put(struct vhost_dev *dev, bool sync) if (!log) { return; } - dev->log = NULL; - dev->log_size = 0; --log->refcnt; if (log->refcnt == 0) { @@ -396,6 +394,9 @@ static void vhost_log_put(struct vhost_dev *dev, bool sync) g_free(log); } + + dev->log = NULL; + dev->log_size = 0; } static bool vhost_dev_log_is_shared(struct vhost_dev *dev)