On 04/05/2013 01:09:50 AM, Alexander Graf wrote:
Am 05.04.2013 um 00:35 schrieb Scott Wood <scottwood@xxxxxxxxxxxxx>:
> On 04/04/2013 05:30:05 PM, Alexander Graf wrote:
>> Am 04.04.2013 um 20:41 schrieb Scott Wood
<scottwood@xxxxxxxxxxxxx>:
>> > On 04/04/2013 07:54:20 AM, Alexander Graf wrote:
>> >> On 03.04.2013, at 03:57, Scott Wood wrote:
>> >> > @@ -460,6 +464,13 @@ void kvm_arch_vcpu_free(struct kvm_vcpu
*vcpu)
>> >> > tasklet_kill(&vcpu->arch.tasklet);
>> >> >
>> >> > kvmppc_remove_vcpu_debugfs(vcpu);
>> >> > +
>> >> > + switch (vcpu->arch.irq_type) {
>> >> > + case KVMPPC_IRQ_MPIC:
>> >> > + kvmppc_mpic_put(vcpu->arch.mpic);
>> >> This doesn't tell the MPIC that this exact CPU is getting
killed. What if we hotplug remove just a single CPU? Don't we have to
deregister the CPU with the MPIC?
>> >
>> > If we ever support hot vcpu removal, yes. We'd probably need
some MPIC code changes to accommodate that, and we wouldn't currently
have a way to test it, so I'd rather make it obviously not supported
for now.
>> Is there any way to break heavily if user space attempts this?
>
> Is there any way for userspace to request this currently? They can
close the vcpu fd, but the vcpu won't actually be destroyed until the
vm goes down.
Are you sure? X86 does CPU hotplug today, so there has to be
something :)
Hot add, or hot remove?
Can you give me any hint on where to look?
kvm_cpu_hotplug() appears to deal with hotplug of *physical* cpus --
and is currently a no-op on powerpc. Other than that, grepping isn't
turning up much.
-Scott
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