From b563b4e3f2dd601e19b46ada31bd176fc0a16efc Mon Sep 17 00:00:00 2001
From: Dirk Brandewie <dirk.brandewie@gmail.com>
Date: Fri, 22 Mar 2013 01:29:28 +0100
Subject: [PATCH] cpufreq / intel_pstate: Add function to check that all MSRs
are valid
Some VMs seem to try to implement some MSRs but not all the registers
the driver needs. Check to make sure all the MSR that we need are
available. If any of the required MSRs are not available refuse to
load.
References: https://bugzilla.redhat.com/show_bug.cgi?id=922923
Reported-by: Josh Stone <jistone@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>
---
drivers/cpufreq/intel_pstate.c | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index f6dd1e761129..cd9c5f4f5805 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -752,6 +752,29 @@ static struct cpufreq_driver intel_pstate_driver = {
static int __initdata no_load;
+static int intel_pstate_msrs_not_valid(void)
+{
+ /* Check that all the msr's we are using are valid. */
+ u64 aperf, mperf, tmp;
+
+ rdmsrl(MSR_IA32_APERF, aperf);
+ rdmsrl(MSR_IA32_MPERF, mperf);
+
+ if (!intel_pstate_min_pstate() ||
+ !intel_pstate_max_pstate() ||
+ !intel_pstate_turbo_pstate())
+ return -ENODEV;
+
+ rdmsrl(MSR_IA32_APERF, tmp);
+ if (!(tmp - aperf))
+ return -ENODEV;
+
+ rdmsrl(MSR_IA32_MPERF, tmp);
+ if (!(tmp - mperf))
+ return -ENODEV;
+
+ return 0;
+}
static int __init intel_pstate_init(void)
{
int cpu, rc = 0;
@@ -764,6 +787,9 @@ static int __init intel_pstate_init(void)
if (!id)
return -ENODEV;
+ if (intel_pstate_msrs_not_valid())
+ return -ENODEV;
+
pr_info("Intel P-state driver initializing.\n");
all_cpu_data = vmalloc(sizeof(void *) * num_possible_cpus());
--
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