HVM

HVM, or hardware-assisted virtualization, is a method of virtualization in which a hypervisor leverages processor and chipset features to run guest operating systems unmodified. It contrasts with earlier approaches that required para-virtualization or binary translation of privileged instructions.

Hardware features include Intel VT-x and AMD-V for CPU virtualization, IOMMU (VT-d, AMD-Vi) for device isolation, and extended page tables (EPT/NPT) to speed memory translation. The hypervisor uses these features to trap and virtualize privileged operations, virtual interrupts, and I/O.

In Xen and similar environments, HVM guest domains run unmodified OS kernels, typically with emulated hardware devices; performance improves when guests use para-virtualized drivers (virtio) for better I/O efficiency.

HVM is widely used in cloud infrastructure and virtualization platforms such as KVM, Xen, and VMware; it enables running Windows, Linux, and other OSes without modification. It coexists with para-virtualization (PV) domains, which offer lower overhead for OS-aware guests.

See also: Intel VT-x, AMD-V, IOMMU, virtualization, KVM, Xen, VMware.