On Fri, Dec 27, 2013 at 7:47 AM, Gleb Natapov <gleb@xxxxxxxxxx> wrote: > On Fri, Dec 27, 2013 at 12:24:22PM +0000, One Thousand Gnomes wrote: >> On Tue, 24 Dec 2013 21:36:01 +0530 >> Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote: >> >> > Adding Dirk.. >> > >> > On 24 December 2013 20:06, Josh Boyer <jwboyer@xxxxxxxxxxxxxxxxx> wrote: >> > > Hi All, >> > > >> > > We've had a report [1] that the pstate driver causes KVM guests to >> > > fail to boot because of a divide error. See the backtrace below. >> > > >> > > 4.839784] Intel P-state driver initializing. >> > > [ 4.859972] Intel pstate controlling: cpu 0 >> > > [ 4.867653] cpufreq: __cpufreq_add_dev: ->get() failed >> > >> > After a call to ->init(), ->get() is supposed to work. >> > @Dirk: Any idea why it failed? >> > >> > And then I don't know what made this divide by zero to happen :) >> >> > > [ 4.878127] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 >> >> Emulator bug perhaps ? >> > KVM does not emulate P-states at all. intel_pstate_init() calls > intel_pstate_msrs_not_valid() before printing "Intel P-state driver > initializing." which suppose to fail since it checks that two reads of > MSR_IA32_APERF return different values, but KVM does not emulate this msr > at all, so both calls should return zero (KVM suppose to inject #GP, all rdmsrl > are patched to be rdmsrl_safe in a guest). > > Anything interesting in host dmesg? Is it reproducible? Seems reproducible. I forgot to link to the actual bug in my original report, but you can find it here: https://bugzilla.redhat.com/show_bug.cgi?id=1046317 Adding Richard and Kashyap on CC. josh -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
