Virtual operating system device communication relying on memory access violations

摘要

Attempts by drivers of a virtualized legacy computer game to communicate with nonexistent legacy game system hardware are converted into calls to actual hardware of the host computer game system. An access control list (ACL) restricting and/or reducing page permissions is used to explicitly forbid the drivers of the legacy computer game operating on the virtualized legacy computer game platform from writing to the MMIO addresses of the legacy computer game system. When the operating system of the virtualized legacy computer game platform attempts to touch its driver memory by writing to the MMIO addresses, the operating system of the host computer game system perceives a memory access violation, suspends the virtual machine implementing the virtualized computer game platform, and passes the intended write to an exception handler of the host operating system. The exception handler of the host operating system translates the attempted hardware access command into the command language of the host operating system and then returns control to the operating system of the virtualized legacy computer game platform. The legacy game is completely unaware of this address translation in that it sees only a successful hardware result and proceeds.