poweroff in 3.2 and 3.3

["Jan Beulich" <jbeulich@novell.com>]

The hypervisor appears to make the assumption that all but the vCPU
XENPF_enter_acpi_sleep is being called on are down (in 3.2 because the
sender of the event check IPI assumes the remote CPU is idle, in 3.3 by
and explicit check in __cpu_disable() - here we also have an incorrect
comment stating that this path can only be used when entering S3).

I can't, however, see how this would be guaranteed on the kernel side
(and apart from that I don't think the hypervisor should be dependent on
kernel behavior here, even if it's dom0). Shouldn't therefore
freeze_domains() not only freeze all DomU-s, but also all non-current
vCPU-s of Dom0?

Thanks, Jan