It's already going to reach 2400 Bytes (which is over half of page
size on 4K page archs), so maybe it's good to have this build-time
check in case it overflows when adding new fields.
Signed-off-by: NPeter Xu <peterx@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>