CVE-2018-12126, CVE-2018-12127, CVE-2018-12130, CVE-2019-11091

The bit is set when microcode provides the mechanism to invoke a flush
of various exploitable CPU buffers by invoking the VERW instruction.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>