Cloud Hypervisor v44.0 Released!

Posted February 3, 2025 by Cloud Hypervisor Team ‐ 2 min read

v44.0

This release has been tracked in our roadmap project as iteration v44.0. The following user visible changes have been made:

Configurable virtio-iommu Address Width

The iommu_address_width option has been added to --platform to allow users to limit the virtio-iommu address space in the guest. (#6900)

Notable Performance Improvements

The VIRTIO_BLK_F_SEG_MAX feature has been enabled for virtio-block devices, which brings significant performance improvements on throughput. (#6885)

The io_uring entries are no longer forced to use async helper workers, delegating the decision to the kernel. This change resolved the issue of having excessive amount of worker threads when io_uring is being used, which is expected to improve performance, such as reducing memory usage and reduce CPU contention.

New Fuzzers

Our continuous fuzzing infrastructure is augmented with two new fuzzers to cover x86 instruction emulator and virtio-vsock.

Notable Bug Fixes

  • Fix short read and short write that impact QCOW and VHDX support. (#6884)
  • Various bug fixes on VHDX support. (#6890, #6899)

Contributors

Many thanks to everyone who has contributed to our release:

v43.0

This release has been tracked in our roadmap project as iteration v43.0. The following user visible changes have been made:

Live Migration over TCP Connections

Support has been added to enable direct live migration from two hosts via TCP connections. This supplements the existing support for migrating over a UNIX socket which can then be tunnelled as desired. The documentation has been updated. (#6850)

Notable Performance Improvements

The VIRTIO_RING_F_INDIRECT_DESC feature has been enabled for virtio-block devices. This significantly increases the throughput of the devices with a small negative impact on latency. (#6826)

Notable Bug Fixes

  • Cloud Hypervisor now accepts VFIO devices that use I/O PCI BARs on non x86-64 architectures. Whether they function depends on the host PCI host bridge support - previously they would be rejected even if the driver did not use these BARs. (#6871)
  • Command line groups were adjusted to ensure that at least one payload parameter was provided if any other VM parameters provided. (#6832)

Contributors

Many thanks to everyone who has contributed to our release:

Download

See the GitHub Release for the release assets.