This post explains overheads of virtio, and introduce vhost that increases performance of virtio. Virtio Review & Vhost Introduction # virtio-net example diagram. [Source] VirtI/O is implemented with virtqueues, shared by the guest and QEMU process. When the guest rings a doorbell after inserting requests into the virtqueue, the context is forwarded to host KVM handler (VM-exit), and again to QEMU process via ioeventfd. QEMU process reads the request from the shared virtqueue, and handles it.
