kernel/intel-pstate-do-not-load-on-VM-that-do-not-report-max-P-state.patch

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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 <dirk.brandewie@gmail.com>
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 <dirk.brandewie@gmail.com>
---
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;