Abstract: Several embodiments of the present invention provide a means for improving data access security in computer systems to support high-security applications, and certain of these embodiments are specifically directed to providing sector-level encryption of a virtual hard disk in a virtual machine environment. More specifically, certain embodiments are directed to providing sector-level encryption by using plug-ins in a virtual machine environment, thereby providing improved data access security in a computer system that supports high-security applications. Certain embodiments also use encryption plug-ins associated with standard encryption software for exchanging data between a virtual machine (VM) and its associated virtual hard drive(s) (VHDs). Moreover, several embodiments of the present invention are directed to the use of plug-in encryption services that interface with, and provide services for, a VM via a VM Encryption API (or its equivalent).

Abstract: A method for emulating the functionality of VGA hardware, wherein the emulator program of the present invention maintains a set of tables that permits the emulator program to branch to a function customized for both the instruction and the operating mode of the VGA hardware. When the customized function has already been generated, the emulator will automatically dispatch directly into the customized function. If an instruction is executed at a time when the VGA operating mode has changed, the addresses of the customized functions are loaded from a second table. If a customized function is not present, a customized function is generated and the tables are updated to point to the addresses of the newly created customized function. As the VGA hardware is switching among operating modes, a customized function is not generated until such time when an actual instruction is executed for the VGA hardware.

Abstract: A method for emulating the functionality of VGA hardware, wherein the emulator program of the present invention maintains a set of tables that permits the emulator program to branch to a function customized for both the instruction and the operating mode of the VGA hardware. When the customized function has already been generated, the emulator will automatically dispatch directly into the customized function. If an instruction is executed at a time when the VGA operating mode has changed, the addresses of the customized functions are loaded from a second table. If a customized function is not present, a customized function is generated and the tables are updated to point to the addresses of the newly created customized function. As the VGA hardware is switching among operating modes, a customized function is not generated until such time when an actual instruction is executed for the VGA hardware.

Abstract: A method for processing software instructions in an emulated computing environment is provided in which instruction blocks from the application programs of a guest computer system are parsed to determine whether the instruction blocks include instructions executable at user level or supervisor level. Those instruction blocks that are executable at user level are passed directly to the processor of the host computer system, and those instruction blocks that are executable at supervisor level, are translated before being passed to the processor for execution. In the case of instruction blocks that include instruction blocks executable at supervisor level, prior to translation, a cache is queried to determine whether a translation for the instruction block is in the case. If a translation is in the cache, the translated version in the cache is provided to the processor for execution. If a translation is not in the cache, translation occurs, and the translated instruction block is saved to the cache.

Abstract: A method for emulating the functionality of VGA hardware, wherein the emulator program of the present invention maintains a set of tables that permits the emulator program to branch to a function customized for both the instruction and the operating mode of the VGA hardware. When the customized function has already been generated, the emulator will automatically dispatch directly into the customized function. If an instruction is executed at a time when the VGA operating mode has changed, the addresses of the customized functions are loaded from a second table. If a customized function is not present, a customized function is generated and the tables are updated to point to the addresses of the newly created customized function. As the VGA hardware is switching among operating modes, a customized function is not generated until such time when an actual instruction is executed for the VGA hardware.

Abstract: A method for performing a write operation to a hard drive or other memory space is provided. The hard drive is represented as at least two files. The first file is a parent drive and includes some content of the hard drive. Writes made to the hard drive are recorded in a second file, known as a differencing drive. Because no changes are made to the content of the parent drive, the content of the hard drive may be rolled back to the content of the parent drive by discarding the differencing drive.

Abstract: A method for processing software instructions in an emulated computing environment is provided in which instruction blocks from the application programs of a guest computer system are parsed to determine whether the instruction blocks include instructions executable at user level or supervisor level. Those instruction blocks that are executable at user level are passed directly to the processor of the host computer system, and those instruction blocks that are executable at supervisor level, are translated before being passed to the processor for execution. In the case of instruction blocks that include instruction blocks executable at supervisor level, prior to translation, a cache is queried to determine whether a translation for the instruction block is in the case. If a translation is in the cache, the translated version in the cache is provided to the processor for execution. If a translation is not in the cache, translation occurs, and the translated instruction block is saved to the cache.