Apparatuses, systems, and methods for hierarchical memory systems are described. A hierarchical memory system can leverage persistent memory to store data that is generally stored in a non-persistent memory, thereby increasing an amount of storage space allocated to a computing system at a lower cost than approaches that rely solely on non-persistent memory. An example method includes receiving an interrupt message by a hypervisor, the interrupt message generated by a hierarchical memory component responsive to receiving a read request initiated by an input/output (I/O) device, gathering, by the hypervisor, address register access information from the hierarchical memory component, and determining, by the hypervisor, a physical location of data associated with the read request.