Xen Developer & Design Summit 2018

Xen is one of most popular virtualization project, many companies and individuals participate in the development, testing and using of Xen. In this presentation, Xudong will give an introduction of Intel QA team's test coverage for Xen, demonstrate the pre check in for new features testing, and post check in for regression testing, as well as test methodology and test framework.

The Xen domU create/destroy and device hotplug rely on xenwatch kernel thread to run xenwatch event callback function for each subscribed xenstore node update. Any event callback function hang would stall the only single xenwatch thread and forbid further domU create/destroy or device hotplug. This talk presents how Xenwatch Multithreading can address the xenwatch stall issue. In addition to the default xenwatch thread, the dom0 will create a per-domU kernel thread for each domU to handle their own xenwatch event. Therefore, domU create/destroy or device hotplug are still allowed even when a specific per-domU xenwatch thread is stalled. This talk first discusses the limitation in single-threaded xenwatch design with some case studies, then explains the basic knowledge on paravirtual driver, and finally presents the challenge, design and implementation of xenwatch multithreading.

One of the killer features of Xen is the ability to contain qemu in a minimal stubdomain. But even though qemu-upstream has been supported by Xen for a long time, stubdomains are compatible only with the ancient qemu-traditional. There were multiple approaches to this problem discussed over time (rumprun, Linux, ...), including some PoC patches. In this presentation I'll explain why we've chosen the Linux solution in Qubes OS and what challenges we faced to make it really work.