KVM Forum 2021

Now that the vfio-user protocol nears completion, the Storage Performance Development Kit is releasing code to emulate complete NVMe PCIe devices to virtual machines from a separate user-space process. This is accomplished by adding a new vfio-user “transport” to the existing SPDK NVMe-oF target. Additionally, SPDK will add a vfio-user transport for its nvme (client) driver to enable SPDK-based applications to connect to these emulated devices, acting as an alternative client to QEMU. In this session, we’ll cover how the emulated NVMe controller is implemented in SPDK and the threading model that provides high bandwidth, low latency, and linear scaling. We will also introduce the client vfio-user library which provides basic PCI abstraction APIs, then the client NVMe library built on top. We’ll wrap up by showing some use cases, performance data, and future development plans.