ucall_init
ucall_init(vm, region->region.guest_phys_addr + region->region.memory_size);
void ucall_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa);
ucall_init(vm, slot0->region.guest_phys_addr + slot0->region.memory_size);
ucall_init(vm, slot0->region.guest_phys_addr + slot0->region.memory_size);