Xen Summit 2026

Future Arm CPUs are evolving toward systems where Virtualization Host Extensions (VHEs) are always enabled. This talk shows how Xen can adapt to the next generation of Arm hardware while continuing to support today’s programmable-VHE and non-VHE systems.
We will walk through the engineering work required to make Xen bootable, and upstreamable on VHE-always platforms. The challenge goes far beyond early boot. We’ll cover VHE changes assumptions around EL2 bring-up, system-register access, MMU setup, exception and trap routing, timers, interrupts, and host/guest world switching.
Attendees will learn how Xen detects and selects VHE policy during boot and secondary CPU bring-up; how vhe=on/off/auto supports different platform capabilities; and how EL1/EL2 system-register abstractions help reduce fragile VHE-specific conditionals. We will also cover the areas most likely to expose hidden assumptions, including MMU state, timer delivery, GICv2/GICv3 virtualization, and VHE-sensitive save/restore paths.
Finally, we will discuss the path from an initial homogeneous Dom0-boot prototype with basic timer and interrupt support to product-quality SMP, testing, and platform validation.