Advisory: XSA-261

Before XSA-261, Xen didn't implement IO-APIC interrupt routing for HPET timers properly, and attempting to configure a IRQ above the legacy PIC range resulted in an array overrun.

This test attempts to configure the non-legacy IRQs for each timer. If vulnerable, Xen will generally crash on the first IRQ attempt, but this does depend on the exact compiled layout of struct domain. If Xen hasn't crashed by the end of the loops, it is most likely not vulnerable.

See also: tests/xsa-261/main.c