vm_guest_mem_fallocate
void vm_guest_mem_fallocate(struct kvm_vm *vm, uint64_t gpa, uint64_t size,
vm_guest_mem_fallocate(vm, gpa, size, true);
vm_guest_mem_fallocate(vm, gpa, size, false);
vm_guest_mem_fallocate(vm, gpa, size, map_shared);