Virtualization

Normally without virtualization

• application layer make user calls to OS
• OS make privileged calls to hardware

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Emulated Virtualization

• host OS/hypervisor still run on the hardware, allocated the resource to guest OS

• guest OS were wrapped a container called virtual machine that can make privileged call and interact with the hardware

• binary translation make these calls into hypervisor call as if host OS calls them

• tend to be slow because of the binary translation

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Para-virtualization

• only works on a small subset of OS, which can be modified to make guest OS’s privileged call into user call calls the hypervisor (hypercalls)
• still trying to trick the hardware

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Hardware assisted virtualization

• hardware itself has become virtualization aware
• CPU contains specific instruction and capabilities and understand it’s performing virtualization
• the calls are redirected to the hypervisor by the hardware and hypervisor handle how’re they executed
• SR-IOV procedure makes devices into multiple logical mini devices allowing the VM to use

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