On Tue, Aug 20, 2019 at 12:34:20AM -0700, Matt Delco wrote: > On Mon, Aug 19, 2019 at 10:09 PM Wanpeng Li <kernellwp@xxxxxxxxx> wrote: > > > > On Tue, 20 Aug 2019 at 12:10, Nadav Amit <nadav.amit@xxxxxxxxx> wrote: > > > These tests pass on bare-metal. > > > > Good to know this. In addition, in linux apic driver, during mode > > switch __setup_APIC_LVTT() always sets lapic_timer_period(number of > > clock cycles per jiffy)/APIC_DIVISOR to APIC_TMICT which can avoid the > > issue Matt report. So is it because there is no such stuff in windows > > or the windows version which Matt testing is too old? > > I'm using Windows 10 (May 2019). Multimedia apps on Windows tend to > request higher frequency clocks, and this in turn can affect how the > kernel configures HW timers. I may need to examine how Windows > typically interacts with the APIC timer and see if/how this changes > when Skype is used. The frequent timer mode changes are not something > I'd expect a reasonably behaved kernel to do. Have you tried analyzing the guest code? If we're lucky, doing so might provide insight into what's going awry. E.g.: Are the LVTT/TMICT writes are coming from a single blob/sequence of code in the guest? Is the unpaired LVTT coming from the same code sequence or is it a new rip entirely? Can you dump the relevant asm code sequences?
