Hardware Virtualization

Hardware Virtualization

1. Full

   • Guest OS is completely isolated from the hardware
   • Example: Parallel Systems
   • VMM runs in Privileged Ring 0
   • Each VM has a VMM
   • Performs Binary Translation of non-virutalizable instructions
   • VM isn't aware of being virtualized
   • Rings
     • Ring 0: Hypervisor
     • Guest OS
     • User Application

2. Para

   • CPU uses hypercalls for operations to handle instructions at compile time
   • Guest OS is partially virtualized
   • Examples: VMWare and Xen
   • Guest OS is aware of being virutalized
   • Guest OS runs on Ring 0
   • Modified Guest OS Kernel is run (Linux or BSD); Windows is not supported
   • Rings
     • Ring 0: Paravirtualized Guest OS
     • Ring 3: User Application

3. Hardware Assisted

   • Uses hypervisor-aware CPU to handle privileged instructions
   • Reduces Overhead
   • Examples: AMD-V and Intel VT
   • Rings
     • Ring 0: VMM, Guest OS
     • Ring 3: User Applications