Guest operating system code optimization for virtual machine

A system for increasing efficiency of guest OS code in a Virtual Machine (VM) running under control of a Virtual Machine Monitor (VMM), wherein the guest OS code includes unsafe instructions that force a processor to exit Virtual Machine context, the system comprising the processor, memory coupled to the processor, and computer code loaded into the memory that performs the following steps:

• enters a virtual machine hardware support mode of the processor;
• installs a code analysis routine that analyzes opcodes of instructions in the guest OS code;
• enters a VM context execution mode that fully virtualizes the processor;
• at run time, detects presence of the opcodes of unsafe instructions in the guest OS code using the code analysis routine;
• and
• executes natively, in the VM context, and without switching to the VMM, substitute instructions instead of at least some of the unsafe instructions;
• and
• (g) resumes the guest OS code execution, after execution of the substitute instructions,
• wherein the code analysis routine is implemented as a guest tool driver in a hypervisor or another virtual machine, and
• wherein the guest tool implements the guest OS code parsing and modification using information about memory mapping of a guest OS kernel.