Hi Josh, Sorry for the slow resopnse you caught me on vacation :-) I do not have either of these VMs ATM to test against. The patch below should solve the problem though It looks like the VM is returning zero for the highest P state (frequency) MSR. The patch will have the driver refuse to load and the system should fall through to one of the other configured governors/ scaling drivers. Is it possible for tyou to test the patch below while I try to get a test setup put together locally? Thanks in advance --Dirk On 03/01/2013 06:13 AM, Josh Boyer wrote: > Hi, > > We've had a report[1] that the intel_pstate driver will panic on boot > under certain virtual machine environments. Thus far it seems VMWare > and Hyper-V both see this. While this may be because of something those > VMs are doing, the driver probably shouldn't cause a panic if it's > getting some iffy data. > commit db138459876467dd1b4785ce2b35c9db31dab056 Author: Dirk Brandewie Date: Mon Mar 4 10:14:42 2013 -0800 cpufreq/intel_pstate: Do not load on VM that do not report max P state. It seems some VMs support the P state MSRs but return zeros. Fail gracefully if we are running in this environment. https://bugzilla.redhat.com/show_bug.cgi?id=916833 Reported-by: jwboyer@redhat.com Signed-off-by: Dirk Brandewie --- drivers/cpufreq/intel_pstate.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index 096fde0..2bfd083 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -662,6 +662,9 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy) cpu = all_cpu_data[policy->cpu]; + if (!policy->cpuinfo.max_freq) + return -ENODEV; + intel_pstate_get_min_max(cpu, &min, &max); limits.min_perf_pct = (policy->min * 100) / policy->cpuinfo.max_freq;