On 20/05/2016 13:47, Alan Jenkins wrote: > Hi > > I'm getting a hard lockup in wait_lapic_expire(). I'm not certain why, > and it didn't seem to reproduce on a second setup. However I found a > suspect in the code for TSC deadline timers. Maybe someone is interested > in my analysis. > > If a guest has a TSC deadline timer set, it's not re-done when the TSC > is adjusted, and will fire at the wrong time. The hrtimer used for > emulation is not being recalculated. If the TSC was set _backwards_, I > think it could trigger a lockup in wait_lapic_expire(). This function is > a busy-loop optimization, which could be tricked into busy-looping for > too long. The expected busy-wait is `lapic_timer_advance_ns`, which > defaults to 0 (I haven't changed it). This was already reported in the past, but nobody really analyzed it. Thanks very much! I'll look at it next week. Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
