Block-Based In-Place Replacement Strategy for x86 Sensitive Instructions in Virtual Machine

It is trendy that virtualization technology is adopted by server and desktop computers recently. Binary translation is an important method to implement full virtualization supporting any guest operating system without modification. Traditional methods use trap or interrupt to catch sensitive instruction's execution. Its performance is influenced by trap's context switch overhead. This article proposes a novel code scanning and replacing strategy, named as Block-based In-Place Replacement. BIPR tries to find a code block whose length is longer than 5 bytes and replaces the block with 5-bytes JMP instruction. The translated code block has same run-time mode as original code. As a result, BIPR's cost is lower than traditional trap methods. Moreover, it gives an optimize strategy, i.e. Super Block-based In-Place Replacement, to reduce unnecessary translation overhead of BIPR and get better performances. Experiment results prove that SBIPR performs pretty.