Interrupt handling is one of the critical subsystem in the hypervisor (HV). It is critical both from correctness and performance perspective. Hyper-V supports multi-processor systems and uses many optimizations to improve performance for interrupt virtualization.
Interrupt handling is done via APIC emulation. For each vCPU, a vAPIC is created in the hypervisor. These vAPIC behaves similar to APIC in a physical system and provide interrupt support to virtual machines. To support operating systems that are not APIC aware, PIC emulation is provided using virtual wire mode as specified in Intel multiprocessor specifications.
In this post, I would talk about how interrupts are virtualized in Hyper-V environment and discuss some of the performance optimizations. (more…)