1. A control method for a virtual machine for executing a virtualization module for providing a virtual machine operating on a physical machine, the physical machine comprising: a plurality of physical CPUs; and a physical memory, the virtualization module comprising a predetermined emulator, the virtualization module operating an OS on the virtual machine, the plurality of physical CPUs being capable of setting an interrupt handler executed upon reception of an interrupt from the virtual machine, the control method comprising: executing, on at least one first physical CPU out of the plurality of physical CPUs, the OS upon the reception of the interrupt; and executing, on at least one second physical CPU out of the plurality of physical CPUs, the predetermined emulator upon the reception of the interrupt; wherein: the physical machine further comprises at least one physical I/O device; the virtualization module provides, to the virtual machine, at least one virtual CPU and at least one virtual I/O device; the control method further comprises: assigning, by the virtualization module, to the at least one virtual I/O device constituting the virtual machine, the at least one physical I/O device one of in a first form in which the at least one physical I/O device is directly used by the single virtual machine, and in a second form in which the at least one physical I/O device is indirectly used via the predetermined emulator by a plurality of the virtual machines; and assigning, by the virtualization module, to the at least one virtual CPU constituting the virtual machine, one of the plurality of physical CPUs one of in a third form in which the one of the plurality of physical CPUs executes the OS upon the reception of the interrupt, and in a fourth form in which the one of the plurality of physical CPUs executes the predetermined emulator upon the reception of the interrupt; the executing, on the at least one first physical CPU out of the plurality of physical CPUs, the OS upon the reception of the interrupt comprises executing the OS, upon reception of an interrupt from the at least one physical I/O device, by the one of the plurality of physical CPUs, when, to the at least one virtual I/O device constituting the virtual machine, the at least one physical I/O device is assigned in the first form in which the at least one physical I/O device is directly used by the single virtual machine, and when, to the at least one virtual CPU constituting the virtual machine, the one of the plurality of physical CPUs is assigned in the third form in which the one of the plurality of physical CPUs executes the OS upon the reception of the interrupt; and the executing, on the at least one second physical CPU out of the plurality of physical CPUs, the predetermined emulator upon the reception of the interrupt comprises executing the predetermined emulator, upon the reception of the interrupt from the at least one physical I/O device, by the one of the plurality of physical CPUs, one of when, to the at least one virtual I/O device constituting the virtual machine, the at least one physical I/O device is assigned in the second form in which the at least one physical I/O device is indirectly used via the predetermined emulator by the plurality of the virtual machines, and when, to the at least one virtual CPU constituting the virtual machine, the one of the plurality of physical CPUs is assigned in the fourth form in which the one of the plurality of physical CPUs executes the predetermined emulator upon the reception of the interrupt.