Transparent memory-mapped emulation of I/O calls

摘要

A virtual-machine-based system provides a mechanism to implement application file I/O operations of protected data by implementing the I/O operations semantics in a shim layer with memory-mapped regions. The semantics of these I/O operations are emulated in a shim layer with memory-mapped regions by using a mapping between a process' address space and a file or shared memory object. Data that is protected from viewing by a guest OS running in a virtual machine may nonetheless be accessed by the process.

主权项

1. In a computer system comprising a virtual machine monitor (VMM) running on system hardware and supporting a virtual machine (VM) having a first application and a guest OS running therein, a method of processing file I/O operations for files, the method comprising:
a first shim program intercepting file I/O calls from the first application, the first shim program running completely within the same VM as the first application and interfacing with the VMM using one or more hypercalls from the first shim to the VMM; the first shim program emulating file I/O semantics of an intercepted file I/O call by mapping a target file to which the intercepted file I/O call was directed to a first memory region; and the first application accessing a version of the target file from the first memory region using memory-mapped I/O.