Re: [PATCH] acpi: Issue _OSC call for native thermal interrupt handling

[Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>]

On Wed, 2016-03-16 at 23:48 +0100, Rafael J. Wysocki wrote:
> On Wednesday, March 16, 2016 03:25:19 PM Srinivas Pandruvada wrote:
> > There are several reports of freeze on enabling HWP (Hardware
> > PStates)
> > feature on Skylake based systems by Intel P states driver. The root
> > cause is identified as the HWP interrupts causing BIOS code to
> > freeze.
> > HWP interrupts uses thermal LVT.
> > Linux natively handles thermal interrupts, but in Skylake based
> > systems
> > SMM will take control of thermal interrupts. This is a problem for
> > several
> > reasons:
> > - It is freezing in BIOS when tries to handle thermal interrupt,
> > which
> > will require BIOS upgrade
> > - With SMM handling thermal we loose all the reporting features of
> > Linux arch/x86/kernel/cpu/mcheck/therm_throt driver
> > - Some thermal drivers like x86-package-temp driver depends on the
> > thermal
> > threshold interrupts
> > - The HWP interrupts are useful for debugging and tuning
> > performance
> > 
> > So we need native handling of thermal interrupts. To inform SMM
> > that
> > OS will handle thermal interrupts, we need to use _OSC under
> > processor
> > scope very early in ACPI initialization flow. This needs to be done
> > before SMM code path looks for _OSC capabilities. The bit 12 of
> > _OSC in processor scope defines whether OS will handle thermal
> > interrupts.
> > When bit 12 is set to 1, OS will handle thermal interrupts.
> > Refer to this document for details on _OSC
> > http://www.intel.com/content/www/us/en/standards/processor-vendor-
> > specific-acpi-specification.html
> > 
> > This change introduces a new function
> > acpi_early_processor_set_osc(),
> > which walks acpi name space and finds acpi processor object and
> > set capability via _OSC method to take over thermal LVT.
> > 
> > Also this change writes HWP status bits to 0 to clear any HWP
> > status
> > bits in intel_thermal_interrupt().
> > 
> > Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel
> > .com>
> 
> Has this version of the patch been tested on a system where the
> problem
> is reproducible?
1.
Yes. I tested on  Yoga 260.
2.
Also in
https://bugzilla.kernel.org/show_bug.cgi?id=110941 
One user confirmed it.
3.
One user in Debian forum
http://forums.debian.net/viewtopic.php?f=7&t=127415

I hope more users will confirm soon as this was reported on many distro
forums also.

I sent this for review and make available for more users to test.
 
> 
> > ---
> >  arch/x86/kernel/cpu/mcheck/therm_throt.c |  8 ++++++
> >  drivers/acpi/acpi_processor.c            | 42
> > +++++++++++++++++++++++++++++++-
> >  drivers/acpi/bus.c                       |  3 +++
> >  drivers/acpi/internal.h                  |  2 ++
> >  4 files changed, 54 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/x86/kernel/cpu/mcheck/therm_throt.c
> > b/arch/x86/kernel/cpu/mcheck/therm_throt.c
> > index 0b445c2..bb331f6 100644
> > --- a/arch/x86/kernel/cpu/mcheck/therm_throt.c
> > +++ b/arch/x86/kernel/cpu/mcheck/therm_throt.c
> > @@ -79,6 +79,8 @@ static atomic_t therm_throt_en	=
> > ATOMIC_INIT(0);
> >  
> >  static u32 lvtthmr_init __read_mostly;
> >  
> > +static bool thermal_hwp_interrupt_support;
> > +
> >  #ifdef CONFIG_SYSFS
> >  #define define_therm_throt_device_one_ro(_name)			
> > 	\
> >  	static DEVICE_ATTR(_name, 0444,				
> > 	\
> > @@ -384,6 +386,9 @@ static void intel_thermal_interrupt(void)
> >  {
> >  	__u64 msr_val;
> >  
> > +	if (thermal_hwp_interrupt_support)
> > +		wrmsrl_safe(MSR_HWP_STATUS, 0);
> > +
> >  	rdmsrl(MSR_IA32_THERM_STATUS, msr_val);
> >  
> >  	/* Check for violation of core thermal thresholds*/
> > @@ -552,6 +557,9 @@ void intel_init_thermal(struct cpuinfo_x86 *c)
> >  	rdmsr(MSR_IA32_MISC_ENABLE, l, h);
> >  	wrmsr(MSR_IA32_MISC_ENABLE, l | MSR_IA32_MISC_ENABLE_TM1,
> > h);
> >  
> > +	if (static_cpu_has(X86_FEATURE_HWP))
> > +		thermal_hwp_interrupt_support = true;
> > +
> >  	/* Unmask the thermal vector: */
> >  	l = apic_read(APIC_LVTTHMR);
> >  	apic_write(APIC_LVTTHMR, l & ~APIC_LVT_MASKED);
> > diff --git a/drivers/acpi/acpi_processor.c
> > b/drivers/acpi/acpi_processor.c
> > index 6979186..5a78279 100644
> > --- a/drivers/acpi/acpi_processor.c
> > +++ b/drivers/acpi/acpi_processor.c
> > @@ -391,7 +391,6 @@ static int acpi_processor_add(struct
> > acpi_device *device,
> >  	if (pr->id >= setup_max_cpus && pr->id != 0)
> >  		return 0;
> >  #endif
> > -
> >  	BUG_ON(pr->id >= nr_cpu_ids);
> >  
> >  	/*
> > @@ -491,6 +490,47 @@ static void acpi_processor_remove(struct
> > acpi_device *device)
> >  }
> >  #endif /* CONFIG_ACPI_HOTPLUG_CPU */
> >  
> 
> It occurs to me that the whole thing is only necessary on x86, so
> maybe it can
> go under a #ifdef?
OK. I will submit a new revision.
> 
> Or even to arch/x86/acpi/ (boot.c or a new file)?
> 
> > +static bool acpi_hwp_native_thermal_lvt_set;
> > +static acpi_status acpi_set_hwp_native_thermal_lvt_osc(acpi_handle
> > handle,
> > +						       u32 lvl,
> > void *context,
> > +						       void **rv)
> > +{
> > +	u8 sb_uuid_str[] = "4077A616-290C-47BE-9EBD-D87058713953";
> > +	u32 capbuf[2];
> > +	struct acpi_osc_context osc_context = {
> > +		.uuid_str = sb_uuid_str,
> > +		.rev = 1,
> > +		.cap.length = 8,
> > +		.cap.pointer = capbuf,
> > +	};
> > +
> > +	if (acpi_hwp_native_thermal_lvt_set)
> > +		return AE_OK;
> > +
> > +	if (!static_cpu_has(X86_FEATURE_HWP))
> > +		return AE_OK;
> 
> This check can be made once in acpi_early_processor_set_osc().
> 
OK.
> > +
> > +	capbuf[0] = 0x0000;
> > +	capbuf[1] = 0x1000; /* set bit 12 */
> > +
> > +	if (ACPI_SUCCESS(acpi_run_osc(handle, &osc_context))) {
> > +		acpi_hwp_native_thermal_lvt_set = true;
> > +		kfree(osc_context.ret.pointer);
> > +	}
> > +
> > +	return AE_OK;
> > +}
> > +
> > +void acpi_early_processor_set_osc(void)
> > +{
> > +	acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT,
> > +			    ACPI_UINT32_MAX,
> > +			    acpi_set_hwp_native_thermal_lvt_osc,
> > +			    NULL, NULL, NULL);
> > +	acpi_get_devices(ACPI_PROCESSOR_DEVICE_HID,
> > +			 acpi_set_hwp_native_thermal_lvt_osc,
> > NULL, NULL);
> > +}
> > +
> >  /*
> >   * The following ACPI IDs are known to be suitable for
> > representing as
> >   * processor devices.
> > diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
> > index 891c42d..7e73aea 100644
> > --- a/drivers/acpi/bus.c
> > +++ b/drivers/acpi/bus.c
> > @@ -1005,6 +1005,9 @@ static int __init acpi_bus_init(void)
> >  		goto error1;
> >  	}
> >  
> > +	/* Set capability bits for _OSC under processor scope */
> > +	acpi_early_processor_set_osc();
> > +
> >  	/*
> >  	 * _OSC method may exist in module level code,
> >  	 * so it must be run after ACPI_FULL_INITIALIZATION
> > diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
> > index 1e6833a..5c787ac 100644
> > --- a/drivers/acpi/internal.h
> > +++ b/drivers/acpi/internal.h
> > @@ -138,6 +138,8 @@ void acpi_early_processor_set_pdc(void);
> >  static inline void acpi_early_processor_set_pdc(void) {}
> >  #endif
> >  
> > +void acpi_early_processor_set_osc(void);
> > +
> >  /* -------------------------------------------------------------
> > -------------
> >                                    Embedded Controller
> >     ---------------------------------------------------------------
> > ----------- */
> > 
> 
I will wait for other comments before submitting another version.

Thanks,
Srinivas

> Thanks,
> Rafael
>