Virtualization Fundamentals

What was the primary motivation behind the development of virtualization in the 1960s?

To reduce the cost of mainframe computers
To simplify the management of business services
To increase the processing power of individual users
To enable concurrent running of diverse workloads on the same physical hardware (correct)

What is the term for the combination of an operating system, its applications, and its virtual resources?

Guest domain
Hypervisor
Virtual resource
Virtual machine (correct)

What is the primary function of the virtualization layer?

To manage the allocation of real hardware resources
To provide isolation guarantees across VMs
To support the coexistence of multiple VMs and provide isolation guarantees (correct)
To enable multiple VMs to exist on a single physical machine

What is the term for the underlying functionality that enables virtual machines to exist?

All of the above (D) Signup and view all the answers

What is a virtual machine, according to the definition?

An efficient, isolated duplicate of a real machine (A) Signup and view all the answers

What is the term used to refer to the operating systems that are deployed on the same physical platform?

Either A or B (C) Signup and view all the answers

Which company has the largest share of server cores and has mandated device manufacturers to develop drivers that can be used by the hypervisor?

VMware (C) Signup and view all the answers

What is the primary responsibility of a VMM in terms of hardware representation?

To ensure that the VM's hardware representation matches the physical platform's hardware (A) Signup and view all the answers

What is the goal of the VMM in terms of performance?

To provide performance to VMs that is as close to native performance as possible (D) Signup and view all the answers

What type of virtualization model uses a full-fledged host OS that manages all of the hardware resources?

Hosted (D) Signup and view all the answers

What is the benefit of consolidation in virtualization?

To decrease cost and improve manageability (C) Signup and view all the answers

What is the benefit of the hosted model in terms of functionality development?

It requires less functionality to be developed for the VMM module. (C) Signup and view all the answers

What is the advantage of virtualization in terms of migration?

It makes setup, teardown, and cloning of virtual machines easier (D) Signup and view all the answers

What is the purpose of the QEMU hardware emulator in the KVM setup?

To act as a virtual interface between the VM and the physical hardware. (C) Signup and view all the answers

What is the advantage of virtualization in terms of availability and reliability?

It allows easy spin up of new VMs on a different physical platform in case of a failure (D) Signup and view all the answers

What is the main advantage of the KVM virtualization solution?

It can quickly adapt to new features and fixes. (B) Signup and view all the answers

What is the primary responsibility of the VMM module in the hosted model?

To provide a virtual platform interface to the guest VMs. (D) Signup and view all the answers

What is the purpose of a service VM in bare-metal virtualization?

To run device drivers and control hardware access (D) Signup and view all the answers

What is the name of the privileged domain in the Xen virtualization software?

dom0 (C) Signup and view all the answers

What is the purpose of protection levels in virtualization setups?

To protect the VMM from the guest OS. (A) Signup and view all the answers

What is the issue with device drivers in bare-metal virtualization?

Device manufacturers need to provide drivers for different hypervisors (C) Signup and view all the answers

What is the term for the process of switching control from the guest OS to the hypervisor in a virtualization setup?

VMExit (A) Signup and view all the answers

What is the term for the process of switching control from the hypervisor back to the guest OS in a virtualization setup?

VMEntry (A) Signup and view all the answers

What is the primary benefit of virtualization for operating systems research?

It provides a fertile ground for testing and development (C) Signup and view all the answers

What is the advantage of virtualization for supporting legacy operating systems?

It provides affordable support for legacy operating systems (B) Signup and view all the answers

What happens when a privileged instruction is issued by the guest OS?

The processor causes a trap to the hypervisor. (A) Signup and view all the answers

What was the issue with the 17 hardware instructions in x86 platforms before 2005?

They didn't cause a trap to the hypervisor, but failed silently. (C) Signup and view all the answers

What is the goal of binary translation?

To run unmodified guest operating systems. (B) Signup and view all the answers

What is done to the code blocks that contain one of the 17 hardware instructions in binary translation?

They are translated into alternate instruction sequences. (B) Signup and view all the answers

What is the main difference between full virtualization and paravirtualization?

Full virtualization requires modified guest OSes, while paravirtualization doesn't. (C) Signup and view all the answers

What are the hypercalls similar to in paravirtualization?

System calls. (C) Signup and view all the answers

Why does the guest OS assume that the change was successful when it issues a privileged instruction?

Because the instruction fails silently. (B) Signup and view all the answers

What is the purpose of caching translated code fragments in binary translation?

To reduce the overhead of the virtualization layer. (C) Signup and view all the answers

What is the consequence of not modifying the guest OS in full virtualization?

The guest OS can run in a virtualized environment without additional software or policies. (A) Signup and view all the answers

What is the name of the strategy used by the hypervisor to handle privileged instructions?

Trap-and-emulate strategy. (D) Signup and view all the answers

What is a key requirement for full virtualization?

The guest OS continues to observe a contiguous, linear address space (D) Signup and view all the answers

What is the purpose of the hypervisor's shadow page table?

To re-map the virtual addresses to machine addresses without considering physical addresses (D) Signup and view all the answers

Why does the hypervisor need to write-protect the page table?

To prevent the guest OS from modifying the page table (B) Signup and view all the answers

What is the benefit of paravirtualization?

The guest OS can explicitly register its page tables with the hypervisor (B) Signup and view all the answers

What is the purpose of the MMU and TLB in memory virtualization?

To help with address translation and free us from implementing translations in software (B) Signup and view all the answers

What is the difference between physical addresses and machine addresses?

Physical addresses are the addresses that the guest thinks are the addresses of the physical resource, while machine addresses correspond to the physical addresses on the underlying physical platform (D) Signup and view all the answers

What happens when the guest OS tries to establish new address mappings in full virtualization?

The guest OS traps into the hypervisor (B) Signup and view all the answers

Why does the hypervisor need to maintain consistency between the two page tables?

To ensure that the mappings in both page tables are consistent (C) Signup and view all the answers

What is the advantage of batching page table updates into a single hypercall in paravirtualization?

It reduces the overhead of the VM exit (A) Signup and view all the answers

What is the benefit of newer hardware platforms in terms of memory virtualization?

They reduce the overhead associated with memory virtualization (D) Signup and view all the answers

What was the primary issue with the initial x86 architecture regarding virtualization?

It had 17 non-virtualizable hardware instructions (A) Signup and view all the answers

What is the purpose of a VM control block?

To capture the state of virtual processors (C) Signup and view all the answers

What is the benefit of extended page tables and tagged TLBs in virtualization?

They reduce the overhead of context switches between VMs (C) Signup and view all the answers

What is the purpose of multiqueue devices in virtualization?

To allow multiple VMs to share a single device (A) Signup and view all the answers

What was added to the x86 architecture to support virtualization?

A new instruction to switch into a new protection mode (C) Signup and view all the answers

What is the purpose of tagging memory structures with VM identifiers?

To allow the hardware to differentiate between VMs (A) Signup and view all the answers

What is the primary concern in the passthrough model of device virtualization?

Exclusive access to a device making sharing difficult (C) Signup and view all the answers

Which device virtualization model allows for device sharing and easy migration of guest VMs?

Hypervisor-direct model (A) Signup and view all the answers

What is the main benefit of the split device driver model compared to the hypervisor-direct model?

Elimination of device emulation overhead (C) Signup and view all the answers

What is the main limitation of the passthrough model in terms of device access?

Exclusive access to a device (D) Signup and view all the answers

Which device virtualization model requires modification of the front-end driver?

Split device driver model (A) Signup and view all the answers

What is the main benefit of the hypervisor-direct model in terms of device access?

Decoupling of guest VMs from physical devices (A) Signup and view all the answers

Which device virtualization model is also known as the VMM-bypass model?

Passthrough model (B) Signup and view all the answers

What is the main challenge of the passthrough model in terms of migration of guest VMs?

Device-specific state that needs to be copied and configured (D) Signup and view all the answers

Which device virtualization model involves a component that resides in a guest VM and a component that resides in a hypervisor layer?

Split device driver model (B) Signup and view all the answers

What is the main benefit of the split device driver model in terms of device management?

Better management of shared devices (D) Signup and view all the answers