Cloud Hypervisor v34.0 Released!

Posted August 10, 2023 by Cloud Hypervisor Team ‐ 2 min read

This release has been tracked in our roadmap project as iteration v34.0. The following user visible changes have been made:

Paravirtualised Panic Device Support

A new device has been added that can communicate when the guest kernel has panicked and share those details with the VMM. This is controlled with a new --pvpanic command line option and JSON API change equivalent. (#5526)

Improvements to VM Core Dump

Requesting to dump the guest memory as core dump will now transparently pause the VM if required; returning to the original state after. (#5604)

QCOW2 Support for Backing Files

The support for QCOW2 files has been enhanced to include support for using backing files. (#5573)

Minimum Host Kernel Bump

The minimum supported host kernel is now 5.13 in order to incorporate a bug fix for KVM_FEATURE_ASYNC_PF_INT functionality. (#5626)

Notable Bug Fixes

  • The x86 emulator is only compiled in if MSHV is compiled in (the kernel carries out this job with KVM) (#5561).
  • A regression has been fixed in VFIO support for devices that use MSI rather than MSI-X (#5658).
  • When triggering a VM shutdown or reset via I/O the vCPU thread will be blocked until that asynchronous event has been received (#5645).
  • Pausing a VM is now a synchronous action with the request only completing when all vCPUs are paused (#5611).
  • Event monitor support now correctly supports concurrent access (#5633).
  • Bug fixes for the QCOW2 file support (#5573).


Many thanks to everyone who has contributed to our release:


See the GitHub Release for the release assets.