Re: [PATCH] xen/cpuhotplug: Fix initial CPU offlining for PV(H) guests

[JÃrgen GroÃ]

On 09.05.20 00:28, Boris Ostrovsky wrote:
> Commit a926f81d2f6c ("xen/cpuhotplug: Replace cpu_up/down() with
> device_online/offline()") replaced cpu_down() with device_offline()
> call which requires that the CPU has been registered before. This
> registration, however, happens later from topology_init() which
> is called as subsys_initcall(). setup_vcpu_hotplug_event(), on the
> other hand, is invoked earlier, during arch_initcall().
>
> As result, booting a PV(H) guest with vcpus < maxvcpus causes a crash.
>
> Move setup_vcpu_hotplug_event() (and therefore setup_cpu_watcher()) to
> late_initcall(). In addition, instead of performing all offlining steps
> in setup_cpu_watcher() simply call disable_hotplug_cpu().
>
> Fixes: a926f81d2f6c (xen/cpuhotplug: Replace cpu_up/down() with device_online/offline()"
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>

Reviewed-by: Juergen Gross <jgross@xxxxxxxx>


Juergen