On Thu, Jun 22, 2017 at 8:43 AM, Wanpeng Li <kernellwp@xxxxxxxxx> wrote: > Hi Ladi, > 2017-06-21 15:06 GMT+08:00 Ladi Prosek <lprosek@xxxxxxxxxx>: >> On AMD hardware, Hyper-V doesn't work nested on KVM if L1 is started with >> more than one vCPU. The problem is in NMI which is heavily used by Windows >> on SMP systems. > > Do you mean there is a PMU NMI watchdog to detect hardlockup in > windows similar to in linux kernel, otherwise how to understand NMI is > heavily used by Windows on SMP systems? I think they just use it for IPI. I see ~60k NMI injections by the time Windows Server 2016 with Hyper-V enabled gets to the login screen. There are no NMI injections without Hyper-V and also no injections with Hyper-V on a single-vcpu VM. As to what led to this design, your guess is as good as mine :) > Regards, > Wanpeng Li
