KVM (Kernel-based Virtual Machine) is a hardware-assisted virtualization technology built directly into the Linux kernel, enabling a Linux system to function as a type-1 (bare-metal) hypervisor.
KVM allows multiple virtual machines (VMs) to run simultaneously on a single physical server, each with its own operating system, while sharing the underlying hardware in a controlled and isolated manner.
What KVM Is in Practice?
In operational terms, KVM:
- Turns the Linux kernel itself into a hypervisor
- Uses CPU virtualization extensions (Intel VT-x, AMD-V)
- Runs each virtual machine as a regular Linux process
- Provides strong isolation between guest systems
KVM is not an add-on layer reminder software; it is part of the core Linux kernel.
How KVM Virtualization Works?
KVM relies on a combination of components:
- Linux kernel
Provides scheduling, memory management, and isolation. - Hardware virtualization extensions
Enable direct execution of guest OS instructions on the CPU. - User-space tools (e.g., QEMU)
Emulate devices, manage VM lifecycle, and provide I/O virtualization.
This architecture allows KVM to achieve near-native performance.
KVM vs Other Virtualization Models
| Aspect | KVM | Type-2 Hypervisors |
| Placement | Inside kernel | On top of the host OS |
| Performance | Near-native | Lower |
| Isolation | Strong | Weaker |
| Scalability | High | Limited |
| Production use | Yes | Rare |
KVM is suitable for enterprise and cloud-scale environments, not just for development use.
Key Characteristics of KVM
1. Performance
Minimal overhead due to direct hardware access and kernel-level integration.
2. Isolation
Each VM has:
- Its own kernel
- Dedicated virtual hardware
- Memory and CPU isolation
A failure inside one VM does not affect others.
3. Flexibility
Supports:
- Multiple operating systems (Linux, Windows, BSD variants)
- Various storage and network backends
- Advanced features such as live migration and snapshots
4. Open Architecture
KVM is open-source and vendor-neutral, reducing lock-in.
KVM in Cloud and Private Cloud
KVM is widely used as the core hypervisor for:
- Public cloud platforms
- Private Cloud deployments
- OpenStack-based infrastructures
- Bare Metal Cloud environments with virtualization layers
It is especially well-suited for custom, performance-sensitive cloud architectures.
KVM and Resource Allocation
KVM allows fine-grained control over:
- CPU pinning and scheduling
- Memory allocation and ballooning
- NUMA awareness
- Network and disk I/O limits
Correct tuning is essential to avoid contention and unpredictable performance.
What KVM Is Not?
❌ Not container technology
❌ Not an emulator
❌ Not a desktop-only virtualization tool
❌ Not automatically secure without a proper configuration
❌ Not a replacement for architectural design
KVM provides the foundation reliability comes from how it is used.
Business Value of KVM
For clients:
- Stable and predictable VM performance
- Strong isolation between workloads
- Compatibility with enterprise operating systems
- Independence from proprietary hypervisors
For us:
- A proven, scalable virtualization foundation
- Full control over virtualization behavior
- Ability to design transparent and predictable cloud platforms
Our Approach to KVM
We treat KVM as:
- A core infrastructure primitive
- The default hypervisor for Private Cloud solutions
- A technology that must be carefully tuned, monitored, and documented
We always explain:
- How are they allocated?
- What level of isolation is provided?
- Where performance limits exist?
- How do failover and recovery work?
KVM works best when: Virtualization is treated as engineering, not abstraction.