On 29/11/2017 19:20, Andi Kleen wrote: > But I haven't looked too closely, but I suspect you'll clobber global > kernel debugger state this way. I checked all callers of update_debugctlmsr, and couldn't find any that could run asynchronously while KVM is caching the value. For example __switch_to_xtra would always run before the sched_in notifier. Thanks, Paolo