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? -- Gleb. -- 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
