Re: [patch 00/53] x86/topology: The final installment

Andrew Cooper
2023-08-08T17:08:52Z

On 08/08/2023 8:40 am, Juergen Gross wrote:
> Tested on an Intel system with Xen:
>
> - PV dom0 is working fine. I couldn't test physical cpu hotplug, but
> removing
>   and then re-adding vcpus to dom0 worked.

It turns out that physical CPU hotplug with XenPV is broken in at least
two ways.

It's dom0 (not Xen) that gets the hot-unplug event, after which the Xen
code in Linux succumbs to a preempt-check failure while trying to
offline the vCPU that aliases the pCPU wanting to go offline.

~Andrew