Run Cloud Virtual Machines Securely and Efficiently

Cloud Hypervisor is an open source Virtual Machine Monitor (VMM) implemented in Rust that focuses on running modern, cloud workloads, with minimal hardware emulation.

Get Started

Get the source on GitHub

Secure 🔒

Minimal emulated devices and implemented in Rust to avoid many common security issues

Fast ⚡️

Boot to userspace in less than 100ms with direct kernel boot

🪟 & 🐧

Supports running modern Linux and Windows guests

Kata Containers

Supported by Kata Containers for running secure containerised workloads

Powerful REST API

Programmatically control the lifecyle of the VM using an HTTP API

Slim

Minimal memory overhead for dense deployments

Cross platform

Runs on both x86-64 and aarch64

Broad device support

Support for wide range of paravirtualised devices and physical device passthrough

Live migration

Migrate VMs from one host to another without interruption

Get Involved:

Cloud Hypervisor is governed openly as part of the Linux Foundation and supported by multiple organisations:

  • Alibaba
  • AMD
  • Ampere
  • ARM
  • ByteDance
  • Cyberus Technology
  • Intel
  • Microsoft
  • SAP
  • Tencent Cloud

Join our Slack community: Invite

Participate in our community activities: Slack channel

Check out and participate in our roadmap on GitHub

For full details of our governance model please see our community repository on GitHub and our founding charter.

For bug reports please use GitHub isssues; for broader community discussions please use our mailing list

Latest news from Cloud Hypervisor project:

Cloud Hypervisor v50.0 Released!

Posted December 19, 2025 by Cloud Hypervisor Team ‐ 2 min read

This release has been tracked in v50.0 group of our roadmap project.

Configurable Nested Virtualization Option on x86_64

The nested=on|off option has been added to --cpu to allow users to configure nested virtualization support in the guest on x86_64 hosts (for both KVM and MSHV). The default value is on to maintain consistency with existing behavior. (#7408)

Compression Support for QCOW2

QCOW2 support has been extended to handle compression clusters based on zlib and zstd. (#7462)

Notable Performance Improvements

Performance of live migration has been improved via an optimized implementation of dirty bitmap maintenance. (#7468)

Live Disk Resizing Support for Raw Images

The /vm.resize-disk API has been introduced to allow users to resize block devices backed by raw images while a guest is running. (#7476)

Developer Experience Improvements

Significant improvements have been made to developer experience and productivity. These include a simplified root manifest, codified and tightened Clippy lints, and streamlined workflows for cargo clippy and cargo test. (#7489)

Improved File-level Locking Support

Block devices now use byte-range advisory locks instead of whole-file locks. While both approaches prevent multiple Cloud Hypervisor instances from simultaneously accessing the same disk image with write permissions, byte-range locks provide better compatibility with network storage backends. (#7494)

Logging Improvements

Logs now include event information generated by the event-monitor module. (#7512)

Notable Bug Fixes

  • Fix several issues around CPUID in the guest (#7485, #7495, #7508)
  • Fix snapshot/restore for Windows Guest (#7492)
  • Respect queue size in block performance tests (#7515)
  • Fix several Serial Manager issues (#7502)
  • Fix several seccomp violation issues (#7477, #7497, #7518)
  • Fix various issues around block and qcow (#7526, #7528, #7537, #7546, #7549)
  • Retrieve MSRs list correctly on MSHV (#7543)
  • Fix live migration (and snapshot/restore) with AMX state (#7534)

Contributors

Many thanks to everyone who has contributed to our release:

Download

See the GitHub Release for the release assets.