zpci_kvm_hook
extern struct zpci_kvm_hook zpci_kvm_hook;
zpci_kvm_hook.kvm_register = kvm_s390_pci_register_kvm;
zpci_kvm_hook.kvm_unregister = kvm_s390_pci_unregister_kvm;
zpci_kvm_hook.kvm_register = NULL;
zpci_kvm_hook.kvm_unregister = NULL;
struct zpci_kvm_hook zpci_kvm_hook;
EXPORT_SYMBOL_GPL(zpci_kvm_hook);
if (zpci_kvm_hook.kvm_register)
return zpci_kvm_hook.kvm_register(zdev, vdev->vdev.kvm);
if (zpci_kvm_hook.kvm_unregister)
zpci_kvm_hook.kvm_unregister(zdev);