This paves the way for implementing the CPU list with an RCU list,
which cannot be traversed in reverse order.
Note that this is the only caller of CPU_FOREACH_REVERSE.
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <20180819091335.22863-11-cota@braap.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>