On 26/07/2017 03:28, peng.h...@zte.com.cn wrote: > > > when the problem happens , windows kernel is checking whether REG_A_UIP is > changing after periodic timer has stopped. windows kernel access REG_A > according to INB instrunction and it will spend several microseconds because > of VM_EXIT.
A vmexit to the RTC timer should be around 10.000 clock cycles, which is less than a microsecond. > update timer has changed to a long expire time (as alarm timer)on the > one hand. > > on the other hand 244 microseconds in one second is too short to hit > the region. > > windows kernel may check REG_A_UIP when considering RTC something wrong. > many windows VM reboot at the same time and rtc periodic timer may delay > badly.. Does Windows do this test when Hyper-V englightenments are enabled (especially hv-relaxed)? It seems to be a Windows issue to me. I'm not sure adding hacks to the device model is the right thing to do, especially because I don't understand why your fix worked. Paolo
