1. A method of providing a plurality of virtual processors, which is carried out by a physical computer including a physical processor and a memory, comprising the steps of: generating, by a first virtual machine manager, a first virtual processor; generating, by a second virtual machine manager executed on the first virtual processor, a second virtual processor; executing, by the second virtual processor, a user program; receiving, by the first virtual machine manager, a call for the first virtual machine manager from the physical processor; analyzing, by the first virtual machine manager, a cause of the call for the first virtual machine manager; determining, by the first virtual machine manager, based on a result of the analyzing, which of the second virtual machine manager and the user program to execute; and instructing, by the first virtual machine manager, based on a result of the determining, the first virtual processor to execute one of the second virtual machine manager and the user program.