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cpufreq / intel_pstate: Add function to check that all MSRs are valid

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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>
This commit is contained in:
Dirk Brandewie 2013-03-22 01:29:28 +01:00 committed by Rafael J. Wysocki
parent 8bb9660418
commit b563b4e3f2
1 changed files with 26 additions and 0 deletions
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26
drivers/cpufreq/intel_pstate.c
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@ -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());