Understanding hypervisor control: Key hardware components in virtualization

• Hypervisors control and manage key hardware resources such as CPU, memory, storage, network interfaces, and peripherals for virtual machines. This abstraction and allocation of hardware resources makes it possible to run multiple independent virtual environments on a single physical system.
• Hypervisor’s resource optimisation features increase the overall efficiency of the IT infrastructure, reducing hardware costs and improving resource utilisation through workload consolidation. Hypervisor isolation ensures security between virtual machines, especially critical in cloud computing and multi-tenant data centre environments.

Virtualization has become an essential part of modern IT infrastructure, enabling organizations to run multiple virtual machines (VMs) on a single physical server. The technology behind virtualization is largely powered by a hypervisor, a software layer that allows virtual machines to interact with the underlying hardware resources. But how exactly does a hypervisor control the hardware? In this blog, we will explore the key hardware components managed by the hypervisor and how it optimizes system resources for virtual environments.

Also read: What is a hypervisor?

Also read: The crucial role of hypervisors in virtualisation

What is a hypervisor?

A hypervisor, also known as a virtual machine monitor (VMM), is responsible for creating and managing virtual machines. There are two types of hypervisors: Type 1 (bare-metal) and Type 2 (hosted). Type 1 hypervisors run directly on the physical hardware, while Type 2 hypervisors run on top of a host operating system. Regardless of the type, a hypervisor abstracts and allocates hardware resources to virtual machines, enabling multiple independent environments to run on a single physical system.

Key hardware components controlled by the hypervisor

1. CPU (Central Processing Unit)
   The CPU is the most critical resource controlled by the hypervisor. Hypervisors allocate virtual CPUs (vCPUs) to each virtual machine, effectively dividing the physical CPU’s processing power. The hypervisor schedules tasks and ensures that each virtual machine gets a fair share of CPU time without interfering with others. It also manages CPU features like hyper-threading and virtualization extensions (such as Intel VT-x or AMD-V) to optimize performance.
2. Memory
   Memory management is another crucial responsibility of the hypervisor. It is in charge of allocating physical RAM to virtual machines, ensuring that each VM has sufficient memory while preventing overcommitting the system’s total resources. Hypervisors use techniques like memory paging, ballooning, and memory sharing to optimize memory usage across multiple VMs. These methods allow for more efficient allocation and reduce the likelihood of system crashes due to memory exhaustion.
3. Storage
   The hypervisor controls storage resources, managing virtual disks (vDisks) that are attached to virtual machines. It abstracts physical storage devices (such as SSDs or HDDs) into virtual storage volumes, which can be easily resized or moved between different VMs. Hypervisors also handle storage I/O operations, such as read/write requests, ensuring that each VM has access to its allocated disk space without performance degradation.
4. Network Interfaces
   Network virtualization is another vital component controlled by the hypervisor. It manages virtual network adapters and assigns them to virtual machines, allowing them to communicate with each other and with external networks. The hypervisor handles network traffic, often providing features like network address translation (NAT), bridging, and virtual LANs (VLANs) to isolate network traffic between VMs. It also ensures the appropriate bandwidth and network isolation for each VM.
5. Peripheral Devices
   In some cases, hypervisors provide virtual access to physical peripheral devices such as USB devices, graphics cards, or network interfaces. This is known as device pass-through or direct I/O, which allows a virtual machine to directly interact with hardware components, bypassing the hypervisor’s abstraction layer for improved performance. For example, GPU pass-through allows virtual machines to use the power of a dedicated graphics card, making it possible to run GPU-intensive workloads in a virtual environment.
6. Security and Isolation
   One of the most critical roles of the hypervisor is ensuring that virtual machines are securely isolated from each other. This is particularly important in multi-tenant environments or data centers. The hypervisor provides hardware-level isolation, ensuring that one VM cannot access or interfere with the resources or data of another VM. This isolation helps to protect the overall system from potential security breaches and ensures that each VM operates independently.

Why hypervisor control is important

Hypervisors optimize hardware resource usage, making it possible to run multiple VMs on a single physical machine. This increases the overall efficiency of IT infrastructures by consolidating workloads, reducing hardware costs, and improving resource utilization. The ability to dynamically allocate resources like CPU, memory, and storage based on demand further enhances performance and scalability in virtualized environments.

Moreover, the hypervisor’s role in security is vital. By isolating virtual machines from one another and managing access to shared hardware resources, it helps prevent security vulnerabilities and breaches. This is particularly critical in cloud computing and multi-tenant data centers, where resources are shared among multiple users.