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.