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virtio/vhost: reset dev->log after syncing

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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 <felipe@nutanix.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Felipe Franciosi 2017-09-20 11:53:06 -07:00 committed by Michael S. Tsirkin
parent 3505a22bcb
commit 5c0ba1be37
1 changed files with 3 additions and 2 deletions
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5
hw/virtio/vhost.c
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@ -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)