[PATCH REPOST v2 0/2 v2] cpu/hotplug: Allow the CPU in CPU_UP_PREPARE state to be brought up again.

[Sebastian Andrzej Siewior]

This is a another repost of the previous patch (#2) and adding Boris
(Ostrovsky)'s suggestion regarding the XEN bits.
The previous posts can be found at
   https://lore.kernel.org/all/20211206152034.2150770-1-bigeasy@xxxxxxxxxxxxx/
   https://lore.kernel.org/all/20211122154714.xaoxok3fpk5bgznz@xxxxxxxxxxxxx/

Sebastian