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Commit b563b4e3 authored by Dirk Brandewie's avatar Dirk Brandewie Committed by Rafael J. Wysocki
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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: default avatarJosh Stone <jistone@redhat.com>
Signed-off-by: default avatarDirk Brandewie <dirk.j.brandewie@intel.com>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 8bb96604

drivers/cpufreq/intel_pstate.c

+26 −0
Original line number Diff line number Diff line
@@ -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());