[PATCH 1/2] cpufreq/intel_pstate: Do not load on VM that do not report max P state.

[dirk . brandewie]

From: Dirk Brandewie <dirk.brandewie@xxxxxxxxx>

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@xxxxxxxxxx
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@xxxxxxxxx>
---
 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;
-- 
1.7.7.6

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