KVM Brings Some Improvements To Linux 3.20

Paolo Bonzini has sent in the KVM pull request for the Linux 3.20 kernel and it includes some interesting changes and features for this important piece of the open-source Linux virtualization stack.

Highlights of the Kernel-based Virtual Machine (KVM) updates for Linux 3.20 include:

- A new optional feature to add a small amount of polling on each executed HLT instruction in the guest, for improving latency by up to 50% for some scenarios. Right now this is a feature that needs to be manually toggled but in the future could be auto-tuned.

- KVM on ARM/AArch64 now supports GICv3 emulation and dirty page tracking. GICv3 is a new version of ARM interrupt controllers introduced last year to the Linux kernel that allow supporting more than eight CPUs, message-based interrupts, and other capabilities.

- Optimizations and fixes for s390 architecture.

- KVM for x86 in Linux 3.20 has support for Page Modification Logging, a new feature of Intel "Broadwell" Xeons tp speed up dirty page tracking.

- Nested virtualization improvements/optimizations for KVM on x86.

More details on the KVM changes for the Linux 3.20 kernel can be found via this pull request.