Hardware virtualizer for supporting recursive virtual computer systems on a host computer system

In a computer system including a general purpose host computer, including software and a .phi. map, and having typical real resources such as a central processing unit, for executing instructions as to processes of a user program, and a main memory, and at least one virtual computer having virtual resources, the virtual computer and virtual resources being simulated duplicates of the host computer and real resources, respectively, the host computer also including an individual virtual machine monitor for controlling each virtual computer, the combination of the host computer and each virtual computer being mapped at levels of operation, each level of the virtual computers having virtual resources and successively higher levels of the combination being identified by a number (n+1) to 0, the levels (n+1) through n to level 1 being virtual operating levels of the virtual computers, n being any decimal integer greater than 0, and the 0 level being the real operating level of the host computer having real resources, wherein the instructions of the user program are mapped to real resources, apparatus in which the host computer further includes a hardware virtualizer comprising:

• (a) register means for controlling access to the individual virtual operating levels (n+1) through n to level 1;
• (b) means invisible to all software of the virtual machine and responsive to said register means for mapping the (n+1)th virtual resources of said (n+1)th level into the nth level and into succeedingly sequentially higher levels to and including level 1, for establishing a relationship between the virtual resource of adjacent levels of the virtual machine;
• (c) means visible at least to privileged software of the virtual machine for indicating a correspondence between selected ones of said processes and selected ones of said real resources only from level 1 to the 0 level of operations;
• and
• (d) means responsive to said register means, said mapping means and said indicating means for establishing a correspondence between said real resources at said 0 level of operation and said virtual resources at said level 1 of operation.