x86: CPU lockup during exception delivery

ISSUE DESCRIPTION When a benign exception occurs while delivering another benign exception, it is architecturally specified that these would be delivered sequentially. There are, however, cases where this results in an infinite loop inside the CPU, which in the virtualized case can be broken only...

x86: Long latency populate-on-demand operation is not preemptible

ISSUE DESCRIPTION When running an HVM domain in Populate-on-Demand mode, Xen would sometimes search the domain for memory to reclaim, in response to demands for population of other pages in the same domain. This search runs without preemption. The guest can, by suitable arrangement of its memory...

x86: populate-on-demand balloon size inaccuracy can crash guests

ISSUE DESCRIPTION The design of the memory populate-on-demand PoD system requires that a guest's memory ballooning driver reach its memory reduction target. The target is not entirely well-defined in terms of the information visible to the appropriate parts of the system, so some unknown set of...