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cpufreq / intel_pstate: Do not load on VM that does 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.

References: https://bugzilla.redhat.com/show_bug.cgi?id=916833
Reported-by: Josh Boyer <jwboyer@redhat.com>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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1 parent 907cc90 commit d3929b832833db870af72479666fa4e4d043e02e @dirk-brandewie dirk-brandewie committed with Rafael J. Wysocki Mar 5, 2013
Showing with 3 additions and 0 deletions.
  1. +3 −0 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;

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