Cloud Hypervisor v29.0 Released!

Posted January 14, 2023 by Cloud Hypervisor Team ‐ 2 min read

This release has been tracked in our roadmap project as iteration v29.0. The following user visible changes have been made:

Release Binary Supports Both MSHV and KVM

On x86-64 the binary included in releases supports both the KVM and MSHV hypervisor with runtime detection to identify the correct hypervisor to use.

Snapshot/Restore and Live Migration Improvements

Improvements have been made to the data structures used for both live migration and snapshot/restore. Unfortunately this has broken compatibility with older versions (support for migrating between major versions is not yet officially supported but has worked for some versions.)

Heap Allocation Improvements

Improvements have been made to the volume of heap allocations when running with virtio-block devices along with a reduction in the peak heap size.

ch-remote Improvements

Support for “pinging” the VMM and shutting the VMM down have been added to ch-remote.

AArch64 Documentation Integration

The documentation for AArch64 support has been integrated into the main README.

virtio-block Counters Enhancement

The counters for the virtio-block device has extended to include min/mean/max latency counters.

TCP Offload Control

The virtio-net device has gained support for controlling the enabling of checksum and offloading. This allows the device to be used in environments where the hardware lacks support for the offloading.

Notable Bug Fixes

  • Update dependencies including a version of linux-loader that addresses an infinite loop issue (details)
  • Fix bugs related to virtio-net including an integer overflow issue (#4924, #4949)
  • Use host cpuid information for L2 cache for older KVM on x86 (#4920)
  • Memory mapped into the guest is now marked as non-dumpable which prevents large core files (#5016)
  • Fix QCOW2 refcount table size (#5034)
  • Fix unpause support on MSHV in dual binary (#5037)
  • Threads inside virtio devices are now shutdown on reboot (#5095)


No functionality has been removed in this release.


  • Support for specifying a directory with MemoryZoneConfig::file or MemoryConfig::file has been deprecated. This was originally used for supporting huge pages or shared memory backing which is now natively supported (#5085)


Many thanks to everyone who has contributed to our release:


See the GitHub Release for the release assets.