Method and system for performing virtual to physical address translations in a virtual machine monitor

A method for determining memory mappings between virtual addresses and physical addresses during a software-based processing of an instruction in a computer system having a virtual memory system, in which multiple devices have concurrent access to virtual memory management data, the method comprising:

• for a first attempt at establishing a memory mapping, attempting to establish a memory mapping for a first virtual address according to the virtual memory system;
• if a first memory mapping is established for the first virtual address according to the virtual memory system during the processing of the instruction, retaining the first memory mapping until processing of the instruction has completed;
• if a memory mapping is not established for the first virtual address according to the virtual memory system during the processing of the instruction, retaining information indicating a failure to establish a memory mapping for the first virtual address until processing of the instruction has completed;
• and
• for a subsequent attempted memory mapping:
• if a stored virtual address for a retained memory mapping matches a second virtual address for the subsequent attempted memory mapping, using the retained memory mapping instead of attempting to establish a new memory mapping for the second virtual address according to the virtual memory system;
• and
• if retained information indicates a failure to establish a memory mapping for the second virtual address, using no memory mapping instead of attempting to establish a new memory mapping for the second virtual address according to the virtual memory system.

A computer program embodied in a tangible computer readable medium, the computer program being executable in a computer system in which multiple devices have concurrent memory access, the computer program comprising:

• a software-based instruction processor for enabling the execution of an instruction as if the instruction were executed on a virtualized computer system, the computer system having a virtual memory system, the execution of the instruction requiring multiple memory accesses to access code and data related to the instruction, each of a plurality of the multiple memory accesses requiring a memory mapping from a virtual address to a physical address in accordance with the virtual memory system;
• and
• a plurality of mapping-data storage locations for storing memory mappings between virtual addresses and physical addresses during the software-based processing of the instruction,
• wherein, when the instruction processor is processing the instruction, for each of the plurality of memory accesses that require a memory mapping, the instruction processor attempts to establish the required memory mapping by determining whether the mapping-data storage locations contain an entry that matches a virtual address of the required memory mapping and,
• if the instruction processor finds a matching entry in the mapping-data storage locations, the instruction processor uses a stored memory mapping from the matching entry, instead of attempting to establish the required memory mapping according to the virtual memory system,
• if the instruction processor does not find a matching entry in the mapping-data storage locations, the instruction processor attempts to establish the required memory mapping according to the virtual memory system and, if the required mapping is established, adding an entry to the mapping-data storage locations indicating the established memory mapping and retaining the entry until the software-based processing of the instruction is completed,
• if the instruction processor does not find a matching entry in the mapping-data storage locations and the required memory mapping is not established according to the virtual memory system, adding an entry to the mapping-data storage locations indicating that the required memory mapping was not established for the virtual address and retaining the entry until the processing of the instruction is completed, and
• if the instruction processor finds a matching entry in the mapping-data storage locations, but the entry indicates that a memory mapping was not established for the virtual address, using no memory mapping instead of attempting to establish the required memory mapping according to the virtual memory system.