vm_unused_gva_gap
gva_t vm_unused_gva_gap(struct kvm_vm *vm, size_t sz, gva_t min_gva);
gva_t mmio_gva = vm_unused_gva_gap(vm, vm->page_size, KVM_UTIL_MIN_VADDR);
gva_t gva_start = vm_unused_gva_gap(vm, sz, min_gva);
gva_t mmio_gva = vm_unused_gva_gap(vm, vm->page_size, KVM_UTIL_MIN_VADDR);
gva = vm_unused_gva_gap(vm, NTEST_PAGES * PAGE_SIZE, KVM_UTIL_MIN_VADDR);