Re: [PATCH] cpufreq/intel_pstate: Add function to check that allMSR's are valid

[Dirk Brandewie]

On 03/20/2013 11:28 AM, Rafael J. Wysocki wrote:
> On Wednesday, March 20, 2013 09:17:24 AM dirk.brandewie@xxxxxxxxx wrote:
> > From: Dirk Brandewie <dirk.brandewie@xxxxxxxxx>
> >
> > 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.
> >
> > Signed-off-by: Dirk Brandewie <dirk.j.brandewie@xxxxxxxxx>
>
> Is this needed for v3.9?  Any pointers to bug reports etc.?

Sorry I saw right after I sent the mail that the bug report was missing

    https://bugzilla.redhat.com/show_bug.cgi?id=922923
    Reported-by: Josh Stone <jistone@xxxxxxxxxx>

Would you like me to spin the patch?

> Rafael
>
>
> > ---
> >   drivers/cpufreq/intel_pstate.c |   26 ++++++++++++++++++++++++++
> >   1 files changed, 26 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
> > index f6dd1e7..cd9c5f4 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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