KVM Forum 2019

On x86 platforms, interrupts are configured and delivered to operating system through either the interrupt controllers(e.g. PIC/APIC) or MSI/MSI-X. Similarly for virtualized x86 system, the same set of technologies are used. However, this is not fundamentally required and for some light weight virtualization usages like Kata Containers and Firecracker, which mainly focus on virtio devices and even MSI/MSI-X is not included due to complexity of PCI, the existing interrupt controllers and interrupt handling flow in both host and guest sides are over-killed. We prototyped a new virtual and simplified interrupt controller which fits current kernel interrupt framework well and meanwhile keeps only minimal code in VMM side. This will present the solution as well as the performance data and demonstrate how it can achieve simple and efficient interrupt handling for virtio-mmio device.