The KVM and Xen feature code for Linux 5.19 doesn't have any major breakthrough features but a number of refinements and other incremental improvements being made for these important components to the open-source virtualization stack.
The Kernel-based Virtual Machine for x86/x86_64 adds new ioctls to set/get the TSC frequency for an entire VM, the ability for user-space to opt-out of hypercall patching, AMD Secure Encrypted Virtualization (SEV) improvements, and various AMD nested virtualization improvements.
KVM for RISC-V has Sv57x4 support for handling more virtual and physical memory. With Linux 5.18 RISC-V added Sv57 support and now it's being built into the KVM side as well. The latest QEMU already has G-stage Sv57x4 mode support. RISC-V with this pull also has various other low-level updates.
KVM virtualization for Arm brings guard pages for EL2 stacks, support for the ARMv8.6 WFxT extension for WFIT/WFET, support for saving/restoring the set of hypercalls exposed to the guest, and various other fixes.
The complete set of KVM feature changes intended for Linux 5.19 is outlined via this pull .
Sent out separately this week were also the Xen updates for Linux 5.19. Xen continues seeing work to protect against possible malicious back-end driver code, support for Xen setups with multiple domains created at boot time, decoupling of the Xen SCSI para-virtualization (PV) interface from kernel internals, and other low-level code work. The Xen changes are outlined here .