On Thu, Nov 17, 2022, Huang, Kai wrote:
> On Wed, 2022-11-16 at 17:11 +0000, Sean Christopherson wrote:
> > static int kvm_x86_check_processor_compatibility(void)
> > {
> > int cpu = smp_processor_id();
> > struct cpuinfo_x86 *c = &cpu_data(cpu);
> >
> > /*
> > * Compatibility checks are done when loading KVM and when enabling
> > * hardware, e.g. during CPU hotplug, to ensure all online CPUs are
> > * compatible, i.e. KVM should never perform a compatibility check on
> > * an offline CPU.
> > */
> > WARN_ON(!cpu_online(cpu));
>
> Looks good to me. Perhaps this also can be removed, though.
Hmm, it's a bit superfluous, but I think it could fire if KVM messed up CPU
hotplug again, e.g. if the for_each_online_cpu() => IPI raced with CPU unplug.
> And IMHO the removing of WARN_ON(!irq_disabled()) should be folded to the patch
> "[PATCH 37/44] KVM: Rename and move CPUHP_AP_KVM_STARTING to ONLINE section".
> Because moving from STARTING section to ONLINE section changes the IRQ status
> when the compatibility check is called.
Yep, that's what I have coded up, just smushed it all together here.
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