CVE-2017-5754

BugLink: http://bugs.launchpad.net/bugs/1742772

After discussions this needs to be in Qemu, to deal with migration and
other complications.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>