>>> + }
>>> + mutex_unlock(&kvm->lock);
>>> +}
>>> +
>>> +static int kvm_s390_set_misc(struct kvm *kvm, struct kvm_device_attr *attr)
>>> +{
>>> + int ret;
>>> + u64 cpc;
>>> +
>>> + switch (attr->attr) {
>>> + case KVM_S390_VM_MISC_CPC:
>>> + ret = -EFAULT;
>>> + if (get_user(cpc, (u64 __user *)attr->addr))
>>> + break;
>>> + kvm_s390_set_cpc(kvm, cpc);
>>> + ret = 0;
>>> + break;
>>> + default:
>>> + ret = -ENXIO;
>>> + break;
>>> + }
>>> + return ret;
>>> +}
>>> +
>>> +static int kvm_s390_get_cpc(struct kvm *kvm, struct kvm_device_attr *attr)
>>> +{
>>> + u64 cpc = kvm->arch.diag318_info.cpc;
>>
>> We could have a possible race with a guest VCPU here, but I guess we
>> don't care.
>>
>
> Better safe than sorry? I'll see how another sync request looks here.
>
Sync requests most probably don't make sense here.
I guess we can leave the code as is. User space won't be able to
recognize the difference either way (as long as the cpc is updated in
one shot). A VCPU could update just before or just after the call.
--
Thanks,
David / dhildenb
