We are enabling the new VT features for interrupt/APIC virtualization in KVM. Although we reduced unique overhead of virtualization over the time, we still see some cases where virtualization of interrupts and APIC is a major source of overhead and latencies. The new features will eliminate and reduce overhead of significant portion of the VM exits associated with interrupt handling for virtualization. This talk explains the new VT extensions in details, including 1) APIC register virtualization, 2) virtual interrupt delivery, and 3) posted-interrupt processing, and then we discuss how we enable those in KVM.
The audience is expected to know about the internals of KVM and x86 virtualization, especially I/O and interrupt handling. If the audience is interested in I/O intensive or real-time systems in virtualization, he/she would have good insights from this talk.