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Commit 9522a2ff authored by Srinivas Pandruvada's avatar Srinivas Pandruvada Committed by Rafael J. Wysocki
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cpufreq: intel_pstate: Enforce _PPC limits 



Use ACPI _PPC notification to limit max P state driver will request.
ACPI _PPC change notification is sent by BIOS to limit max P state
in several cases:
- Reduce impact of platform thermal condition
- When Config TDP feature is used, a changed _PPC is sent to
follow TDP change
- Remote node managers in server want to control platform power
via baseboard management controller (BMC)

This change registers with ACPI processor performance lib so that
_PPC changes are notified to cpufreq core, which in turns will
result in call to .setpolicy() callback. Also the way _PSS
table identifies a turbo frequency is not compatible to max turbo
frequency in intel_pstate, so the very first entry in _PSS needs
to be adjusted.

This feature can be turned on by using kernel parameters:
intel_pstate=support_acpi_ppc

Signed-off-by: default avatarSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
[ rjw: Minor cleanups ]
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent eaa2c3ae

Documentation/kernel-parameters.txt

+2 −0
Original line number Diff line number Diff line
@@ -1661,6 +1661,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted. 
		hwp_only

			Only load intel_pstate on systems which support

			hardware P state control (HWP) if available.

		support_acpi_ppc

			Enforce ACPI _PPC performance limits.



	intremap=	[X86-64, Intel-IOMMU]

			on	enable Interrupt Remapping (default)

drivers/cpufreq/Kconfig.x86

+1 −0
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ 
config X86_INTEL_PSTATE

       bool "Intel P state control"

       depends on X86

       select ACPI_PROCESSOR if ACPI

       help

          This driver provides a P state for Intel core processors.

	  The driver implements an internal governor and will become

drivers/cpufreq/intel_pstate.c

+134 −2
Original line number Diff line number Diff line
@@ -41,6 +41,10 @@ 
#define ATOM_TURBO_RATIOS	0x66c

#define ATOM_TURBO_VIDS		0x66d



#ifdef CONFIG_ACPI

#include <acpi/processor.h>

#endif



#define FRAC_BITS 8

#define int_tofp(X) ((int64_t)(X) << FRAC_BITS)

#define fp_toint(X) ((X) >> FRAC_BITS)
@@ -174,6 +178,8 @@ struct _pid { 
 * @prev_cummulative_iowait: IO Wait time difference from last and

 *			current sample

 * @sample:		Storage for storing last Sample data

 * @acpi_perf_data:	Stores ACPI perf information read from _PSS

 * @valid_pss_table:	Set to true for valid ACPI _PSS entries found

 *

 * This structure stores per CPU instance data for all CPUs.

 */
@@ -192,6 +198,10 @@ struct cpudata { 
	u64	prev_tsc;

	u64	prev_cummulative_iowait;

	struct sample sample;

#ifdef CONFIG_ACPI

	struct acpi_processor_performance acpi_perf_data;

	bool valid_pss_table;

#endif

};



static struct cpudata **all_cpu_data;
@@ -260,6 +270,9 @@ static struct pstate_adjust_policy pid_params; 
static struct pstate_funcs pstate_funcs;

static int hwp_active;



#ifdef CONFIG_ACPI

static bool acpi_ppc;

#endif



/**

 * struct perf_limits - Store user and policy limits
@@ -333,6 +346,111 @@ static struct perf_limits *limits = &performance_limits; 
static struct perf_limits *limits = &powersave_limits;

#endif



#ifdef CONFIG_ACPI

/*

 * The max target pstate ratio is a 8 bit value in both PLATFORM_INFO MSR and

 * in TURBO_RATIO_LIMIT MSR, which pstate driver stores in max_pstate and

 * max_turbo_pstate fields. The PERF_CTL MSR contains 16 bit value for P state

 * ratio, out of it only high 8 bits are used. For example 0x1700 is setting

 * target ratio 0x17. The _PSS control value stores in a format which can be

 * directly written to PERF_CTL MSR. But in intel_pstate driver this shift

 * occurs during write to PERF_CTL (E.g. for cores core_set_pstate()).

 * This function converts the _PSS control value to intel pstate driver format

 * for comparison and assignment.

 */

static int convert_to_native_pstate_format(struct cpudata *cpu, int index)

{

	return cpu->acpi_perf_data.states[index].control >> 8;

}



static void intel_pstate_init_acpi_perf_limits(struct cpufreq_policy *policy)

{

	struct cpudata *cpu;

	int turbo_pss_ctl;

	int ret;

	int i;



	if (!acpi_ppc)

		return;



	cpu = all_cpu_data[policy->cpu];



	ret = acpi_processor_register_performance(&cpu->acpi_perf_data,

						  policy->cpu);

	if (ret)

		return;



	/*

	 * Check if the control value in _PSS is for PERF_CTL MSR, which should

	 * guarantee that the states returned by it map to the states in our

	 * list directly.

	 */

	if (cpu->acpi_perf_data.control_register.space_id !=

						ACPI_ADR_SPACE_FIXED_HARDWARE)

		goto err;



	/*

	 * If there is only one entry _PSS, simply ignore _PSS and continue as

	 * usual without taking _PSS into account

	 */

	if (cpu->acpi_perf_data.state_count < 2)

		goto err;



	pr_debug("CPU%u - ACPI _PSS perf data\n", policy->cpu);

	for (i = 0; i < cpu->acpi_perf_data.state_count; i++) {

		pr_debug("     %cP%d: %u MHz, %u mW, 0x%x\n",

			 (i == cpu->acpi_perf_data.state ? '*' : ' '), i,

			 (u32) cpu->acpi_perf_data.states[i].core_frequency,

			 (u32) cpu->acpi_perf_data.states[i].power,

			 (u32) cpu->acpi_perf_data.states[i].control);

	}



	/*

	 * The _PSS table doesn't contain whole turbo frequency range.

	 * This just contains +1 MHZ above the max non turbo frequency,

	 * with control value corresponding to max turbo ratio. But

	 * when cpufreq set policy is called, it will call with this

	 * max frequency, which will cause a reduced performance as

	 * this driver uses real max turbo frequency as the max

	 * frequency. So correct this frequency in _PSS table to

	 * correct max turbo frequency based on the turbo ratio.

	 * Also need to convert to MHz as _PSS freq is in MHz.

	 */

	turbo_pss_ctl = convert_to_native_pstate_format(cpu, 0);

	if (turbo_pss_ctl > cpu->pstate.max_pstate)

		cpu->acpi_perf_data.states[0].core_frequency =

					policy->cpuinfo.max_freq / 1000;

	cpu->valid_pss_table = true;

	pr_info("_PPC limits will be enforced\n");



	return;



 err:

	cpu->valid_pss_table = false;

	acpi_processor_unregister_performance(policy->cpu);

}



static void intel_pstate_exit_perf_limits(struct cpufreq_policy *policy)

{

	struct cpudata *cpu;



	cpu = all_cpu_data[policy->cpu];

	if (!cpu->valid_pss_table)

		return;



	acpi_processor_unregister_performance(policy->cpu);

}



#else

static void intel_pstate_init_acpi_perf_limits(struct cpufreq_policy *policy)

{

}



static void intel_pstate_exit_perf_limits(struct cpufreq_policy *policy)

{

}

#endif



static inline void pid_reset(struct _pid *pid, int setpoint, int busy,

			     int deadband, int integral) {

	pid->setpoint = int_tofp(setpoint);
@@ -1398,18 +1516,27 @@ static int intel_pstate_cpu_init(struct cpufreq_policy *policy) 
	policy->cpuinfo.min_freq = cpu->pstate.min_pstate * cpu->pstate.scaling;

	policy->cpuinfo.max_freq =

		cpu->pstate.turbo_pstate * cpu->pstate.scaling;

	intel_pstate_init_acpi_perf_limits(policy);

	policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;

	cpumask_set_cpu(policy->cpu, policy->cpus);



	return 0;

}



static int intel_pstate_cpu_exit(struct cpufreq_policy *policy)

{

	intel_pstate_exit_perf_limits(policy);



	return 0;

}



static struct cpufreq_driver intel_pstate_driver = {

	.flags		= CPUFREQ_CONST_LOOPS,

	.verify		= intel_pstate_verify_policy,

	.setpolicy	= intel_pstate_set_policy,

	.get		= intel_pstate_get,

	.init		= intel_pstate_cpu_init,

	.exit		= intel_pstate_cpu_exit,

	.stop_cpu	= intel_pstate_stop_cpu,

	.name		= "intel_pstate",

};
@@ -1453,8 +1580,7 @@ static void copy_cpu_funcs(struct pstate_funcs *funcs) 


}



#if IS_ENABLED(CONFIG_ACPI)

#include <acpi/processor.h>

#ifdef CONFIG_ACPI



static bool intel_pstate_no_acpi_pss(void)

{
@@ -1660,6 +1786,12 @@ static int __init intel_pstate_setup(char *str) 
		force_load = 1;

	if (!strcmp(str, "hwp_only"))

		hwp_only = 1;



#ifdef CONFIG_ACPI

	if (!strcmp(str, "support_acpi_ppc"))

		acpi_ppc = true;

#endif



	return 0;

}

early_param("intel_pstate", intel_pstate_setup);