VMexecution

VMexecution refers to the process by which a virtual machine executes software on physical hardware through a virtualization layer. In a typical setup, a hypervisor or virtual machine monitor sits between the guest operating system and the host hardware, presenting each VM with an abstract set of resources such as CPU, memory, storage, and peripherals. The guest runs its code as if on real hardware, while the hypervisor mediates access to host resources to maintain isolation between VMs.

Execution models and techniques vary. Hardware-assisted virtualization uses processor features (for example, VT-x or AMD-V) to trap and virtualize privileged instructions with minimal overhead, enabling unmodified guest operating systems to run. Full virtualization provides complete hardware abstraction, while paravirtualization requires a guest OS modified to cooperate with the hypervisor through hypercalls. Some environments employ binary translation to convert guest code on the fly or use just-in-time compilation within the VM to optimize performance.

Key architectural components include the hypervisor, the virtual CPU, virtual memory management that maps guest addresses to host physical memory, and device I/O virtualization with device emulation. Hypervisors can be classified as Type 1 (bare-metal) or Type 2 (hosted), affecting how they access hardware and manage resources.

Performance and security considerations are central to VMexecution. Virtualization introduces overhead compared with native execution but offers strong isolation, portability, and flexible resource management. Risks include potential side-channel vulnerabilities and the possibility of a VM escape if the hypervisor is compromised.

See also: virtualization, hypervisor, VM monitor, virtual machine, container.