target/ppc: fix icount support on Book-e vms accessing SPRs
Failing to guard SPR access with gen_io_start/gen_stop_exception
causes "Bad icount read" exceptions when running VMs with
e500mc and e500v2 CPUs with an icount parameter.
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Greg Kurz <groug@kaod.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Vitaly Cheptsov <cheptsov@ispras.ru>
Message-Id: <
20210303140851.78383-1-cheptsov@ispras.ru>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>