This release has been tracked in our roadmap
project as iteration
v41.0. The following user visible changes have been made:

Experimental "Pvmemcontrol" Support

VMM support has been added for this experimental functionality (requires
currently out of tree Linux kernel patches) to allow guests to control its
physical memory properties to allow optimisations and security features.
(#6318, #6467)

Sandboxing With Landlock Support

Support for restricting the VMM process using the Linux kernel "Landlock" API
has been added - this can be used to restrict the files (and the read/write
permissions) that the VMM process can access. This adds another layer of
security alongside the existing sycall filters (seccomp) - this can be
enabled with --landlock and fully documentated. (#5170)

Notable Performance Improvements

• Reduced heap allocations in virtio-net via the use of a cache of Iovec
  structures (virtio-devices: net: reduce vec allocations for iovec conversion #6636)
• Notification suppression ("EVENT_IDX") support has been added to
  virtio-block giving a 60% improvement in single queue block throughput and
  IOPs performance (EVENT_IDX support to virtio-block #6580)
• Correct size used for status field in virtio-block state (block: fix status value size #6586)

Notable Bug Fixes

• Avoid panic on out-of-bounds PCI MSI-X access (pci: validate index before accessing MSI-X arrays #6657)
• Fix undefined behaviour on AArch64 leading to wrong optimisation on KVM API
  access (hypervisor: kvm: aarch64: fix get_device_attr() UB #6647)
• Rust v1.80.0 added use of fcntl syscall on debug assertions so this is now
  included in the virtio-device seccomp filters for tests that use this (virtio-devices: allow vsock to call fcntl in debug #6648)
• Short reads are now handled correctly in the virtio-vsock device (cloud-hypervisor vm is crashing if we connect to VSOCK socket from the host side with ncat/socat and kill the app with <ctrl>+c without connecting to any port #6621)
• Fix undefined behaviour on TTY ioctl leading to wrong optimisation (virtio-devices: fix UB getting tty size #6568)

Contributors

Many thanks to everyone who has contributed to our release:

• Alyssa Ross [email protected]
• Bo Chen [email protected]
• Changyuan Lyu [email protected]
• Jinank Jain [email protected]
• Julian Stecklina [email protected]
• Muminul Islam [email protected]
• Nuno Das Neves [email protected]
• Praveen K Paladugu [email protected]
• Rob Bradford [email protected]
• Songqian Li [email protected]
• Wei Liu [email protected]
• Yuanchu Xie [email protected]
• ihciah [email protected]
• wuxinyue [email protected]