Introduction to StratoVirt
Overview
StratoVirt is an enterprise-class Virtual Machine Monitor (VMM) oriented to cloud data centers in the computing industry. It uses a unified architecture to support VM, container, and serverless scenarios. StratoVirt has competitive advantages in key technologies such as lightweight low noise, software and hardware synergy, and Rust language-level security. StratoVirt reserves component-based assembling capabilities and APIs in the architecture design. Advanced features can be flexibly assembled as required until they evolve to support standard virtualization. In this way, StratoVirt can strike a balance between feature requirements, application scenarios, and flexibility.
Architecture Description
The StratoVirt core architecture consists of three layers from top to bottom:
- External API: compatible with the QEMU Monitor Protocol (QMP), has complete OCI compatibility capabilities, and supports interconnection with libvirt.
- BootLoader: discards the traditional BIOS+GRUB boot mode to achieve fast boot in lightweight scenarios, and provides UEFI boot support for standard VMs.
- Emulated mainboard:
- MicroVM: Fully utilizes software and hardware collaboration capabilities, simplifies device models, and provides low-latency resource scaling capabilities.
- Standard VM: implements UEFI boot with constructed ACPI tables. Virtio-pci and VFIO devices can be attached to greatly improve the VM I/O performance.
Figure 1 shows the overall architecture.
Figure 1 Overall architecture of StratoVirt
Features
- Highly isolated based on hardware.
- Fast cold boot: Benefiting from the minimalist design, a microVM can be started within 50ms.
- Low memory overhead: StratoVirt works with a memory footprint of less than 4 MB.
- I/O enhancement: StratoVirt offers normal I/O capabilities and minimalist I/O device emulation.
- OCI compatibility: StratoVirt works with iSula and Kata containers, and can be integrated into the Kubernetes ecosystem perfectly.
- Multi-platform support: StratoVirt fully supports Intel and Arm platforms.
- Extensibility: StratoVirt has interface and design for importing more features, and can be extended to support standard virtualization.
- Security: fewer than 46 syscalls while running.
Implementation
Running Architecture
- A StratoVirt VM is an independent process in Linux. The process has three types of threads: main thread, vCPU thread, and I/O thread:
- The main thread is a cycle for asynchronously collecting and processing events from external modules, such as a vCPU thread.
- Each vCPU has a thread to handle trap events of this vCPU.
- I/O threads can be configured for I/O devices to improve I/O performance.
Restrictions
- Only the Linux operating system is supported, and the recommended kernel versions are 4.19 and 5.10.
- Only Linux is supported as the operating system of the VM, and the recommended kernel versions are 4.19 and 5.10.
- A maximum of 254 CPUs are supported.
