Re: [PATCH v4 1/2] KVM: remove NULL return path for vcpu ids >= KVM_MAX_VCPUS

Radim Krčmář
2016-04-27T14:40:14Z

2016-04-27 05:40-0400, Gerg Kurz:
> Quoting Greg Kurz <gkurz@linux.vnet.ibm.com>:
>
>> Commit c896939f7cff ("KVM: use heuristic for fast VCPU lookup by id") added
>> a return path that prevents vcpu ids to exceed KVM_MAX_VCPUS. This is a
>> problem for powerpc where vcpu ids can grow up to 8*KVM_MAX_VCPUS.
>>
>> This patch simply reverses the logic so that we only try fast path if the
>> vcpu id can be tried as an index in kvm->vcpus[]. The slow path is not
>> affected by the change.
>>
>> Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
>> ---
>
> Radim,
>
> I think this sanity check is only needed because kvm_get_vcpu() use the
> id as an index in kvm->vcpus[]. Checking against the new KVM_MAX_VCPU_ID
> would be clearly wrong here.

I agree, checking KVM_MAX_VCPU_ID would be pointless.

> And this patch got two R-b tags already. Do you agree we keep it ?

Yes, thanks.