This doesn't require write access to the CPU structure.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <158941060817.240484.14621015211317485106.stgit@bahia.lan>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>