A virtualized system is provided. The virtualized system includes: a memory device; a processor configured to provide a virtualization environment; a direct memory access device configured to perform a function of direct memory access to the memory device; and a memory management circuit configured to manage a core access of the processor to the memory device and a direct access of the direct memory access device to the memory device. The processor is further configured to provide: a plurality of guest operating systems that run independently from each other on a plurality of virtual machines of the virtualization environment; and a hypervisor configured to control the plurality of virtual machines in the virtualization environment and control the memory management circuit to block the direct access when a target guest operating system controlling the direct memory access device, among the plurality of guest operating systems is rebooted.