Eric Blake discusses the intricacies of QEMU devices, explaining how emulation works by mimicking what an OS would see on bare-metal hardware. He delves into the details of different accelerators like KVM and TCG, highlighting how they allow for efficient emulation across different hardware platforms. The concept of paravirtualization with virtio devices is explored, showcasing how they minimize vmexits and optimize data transfer between guest memory and storage. Blake also touches on network card emulation with e1000 and virtio-net devices. Ultimately, QEMU provides a platform for running guest OS instructions within a simulated memory map, enabling the manipulation of specific side effects akin to bare-metal execution.
https://www.qemu.org/2018/02/09/understanding-qemu-devices/