The QEMU emulated NVMe device is used by developers and users alike to develop, test and verify device drivers and tools. The emulated device is in rapid development and with QEMU 6.0, the device was updated to support a number of core additional features such as an update to NVMe v1.4, universal Deallocated and Unwritten Logical Block Error support, enhanced PMR and CMB support as well as a number of experimental features such as Zoned Namespaces, multipath I/O, namespace sharing and DIF/DIX end-to-end data protection.

This talk presents the design and implementation of libvfn, a new open-source library for interacting with PCIe-based NVMe devices from user-space using VFIO. The core of the library is excessively low-level and aims to allow NVMe controller verification and testing teams to interact with devices at the register and queue level. While the library ships with a production ready NVMe driver with a high-level API, the library is designed to expose enough low-level VFIO functionality with which custom drivers can be implemented for any PCIe device as required by the application.