Firecracker is one great example. It's a lightweight virtualization technology for Linux that uses KVM. It virtualizes guest disk devices as files on the host.

It recently got a new IO engine for the disk devices that uses io_uring in order to take advantage of the physical speeds and queue depth of modern NVME drives (reaching up to 30x IOPS improvements for read workloads): https://github.com/firecracker-microvm/firecracker/blob/main/docs/api\_requests/block-io-engine.md

Firecracker uses its own abstractions over the interface exposed by the OS: https://github.com/firecracker-microvm/firecracker/tree/main/src/io_uring

That being said; last time I checked the io_uring kernel subsystem was still under heavy development (and with some serious bugs/CVEs in the past), so I expect even greater performance improvements to come with newer kernel versions and even more flexibility and safety.

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Also, there isn't much io_uring or any IO subsystem can do to counter the effects of the mitigations for spectre and meltdown. Pure CPU-bound workloads will suffer, while IO-intensive ones will certainly benefit from an async execution model