On Tue, Jul 06, 2021, Paolo Bonzini wrote: > On 03/07/21 00:04, isaku.yamahata@xxxxxxxxx wrote: > > struct kvm_arch { > > + unsigned long vm_type; > > Also why not just int or u8? Heh, because kvm_dev_ioctl_create_vm() takes an "unsigned long" for the type and it felt wrong to store it as something else. Storing it as a smaller field should be fine, I highly doubt we'll get to 256 types anytime soon :-) I think kvm_x86_ops.is_vm_type_supported() should take the full size though.