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intel_pstate: Add support for HWP 

Add support of Hardware Managed Performance States (HWP) described in Volume 3
section 14.4 of the SDM.

With HWP enbaled intel_pstate will no longer be responsible for selecting P
states for the processor. intel_pstate will continue to register to
the cpufreq core as the scaling driver for CPUs implementing
HWP. In HWP mode intel_pstate provides three functions reporting
frequency to the cpufreq core, support for the set_policy() interface
from the core and maintaining the intel_pstate sysfs interface in
/sys/devices/system/cpu/intel_pstate.  User preferences expressed via
the set_policy() interface or the sysfs interface are forwared to the
CPU via the HWP MSR interface.

Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Dirk Brandewie 2014-11-06 09:40:47 -08:00 committed by Rafael J. Wysocki
parent 7787388772
commit 2f86dc4cdd
4 changed files with 165 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
Documentation/cpu-freq/intel-pstate.txt
View File

@ -1,17 +1,28 @@
Intel P-state driver
--------------------
This driver implements a scaling driver with an internal governor for
Intel Core processors. The driver follows the same model as the
Transmeta scaling driver (longrun.c) and implements the setpolicy()
instead of target(). Scaling drivers that implement setpolicy() are
assumed to implement internal governors by the cpufreq core. All the
logic for selecting the current P state is contained within the
driver; no external governor is used by the cpufreq core.
This driver provides an interface to control the P state selection for
SandyBridge+ Intel processors. The driver can operate two different
modes based on the processor model legacy and Hardware P state (HWP)
mode.
Intel SandyBridge+ processors are supported.
In legacy mode the driver implements a scaling driver with an internal
governor for Intel Core processors. The driver follows the same model
as the Transmeta scaling driver (longrun.c) and implements the
setpolicy() instead of target(). Scaling drivers that implement
setpolicy() are assumed to implement internal governors by the cpufreq
core. All the logic for selecting the current P state is contained
within the driver; no external governor is used by the cpufreq core.
New sysfs files for controlling P state selection have been added to
In HWP mode P state selection is implemented in the processor
itself. The driver provides the interfaces between the cpufreq core and
the processor to control P state selection based on user preferences
and reporting frequency to the cpufreq core. In this mode the
internal governor code is disabled.
In addtion to the interfaces provided by the cpufreq core for
controlling frequency the driver provides sysfs files for
controlling P state selection. These files have been added to
/sys/devices/system/cpu/intel_pstate/
max_perf_pct: limits the maximum P state that will be requested by
@ -33,7 +44,9 @@ frequency is fiction for Intel Core processors. Even if the scaling
driver selects a single P state the actual frequency the processor
will run at is selected by the processor itself.
New debugfs files have also been added to /sys/kernel/debug/pstate_snb/
For legacy mode debugfs files have also been added to allow tuning of
the internal governor algorythm. These files are located at
/sys/kernel/debug/pstate_snb/ These files are NOT present in HWP mode.
deadband
d_gain_pct

3
Documentation/kernel-parameters.txt
View File

@ -1446,6 +1446,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
disable
Do not enable intel_pstate as the default
scaling driver for the supported processors
no_hwp
Do not enable hardware P state control (HWP)
if available.
intremap= [X86-64, Intel-IOMMU]
on enable Interrupt Remapping (default)

41
arch/x86/include/uapi/asm/msr-index.h
View File

@ -152,6 +152,45 @@
#define MSR_CC6_DEMOTION_POLICY_CONFIG 0x00000668
#define MSR_MC6_DEMOTION_POLICY_CONFIG 0x00000669
/* Hardware P state interface */
#define MSR_PPERF 0x0000064e
#define MSR_PERF_LIMIT_REASONS 0x0000064f
#define MSR_PM_ENABLE 0x00000770
#define MSR_HWP_CAPABILITIES 0x00000771
#define MSR_HWP_REQUEST_PKG 0x00000772
#define MSR_HWP_INTERRUPT 0x00000773
#define MSR_HWP_REQUEST 0x00000774
#define MSR_HWP_STATUS 0x00000777
/* CPUID.6.EAX */
#define HWP_BASE_BIT (1<<7)
#define HWP_NOTIFICATIONS_BIT (1<<8)
#define HWP_ACTIVITY_WINDOW_BIT (1<<9)
#define HWP_ENERGY_PERF_PREFERENCE_BIT (1<<10)
#define HWP_PACKAGE_LEVEL_REQUEST_BIT (1<<11)
/* IA32_HWP_CAPABILITIES */
#define HWP_HIGHEST_PERF(x) (x & 0xff)
#define HWP_GUARANTEED_PERF(x) ((x & (0xff << 8)) >>8)
#define HWP_MOSTEFFICIENT_PERF(x) ((x & (0xff << 16)) >>16)
#define HWP_LOWEST_PERF(x) ((x & (0xff << 24)) >>24)
/* IA32_HWP_REQUEST */
#define HWP_MIN_PERF(x) (x & 0xff)
#define HWP_MAX_PERF(x) ((x & 0xff) << 8)
#define HWP_DESIRED_PERF(x) ((x & 0xff) << 16)
#define HWP_ENERGY_PERF_PREFERENCE(x) ((x & 0xff) << 24)
#define HWP_ACTIVITY_WINDOW(x) ((x & 0xff3) << 32)
#define HWP_PACKAGE_CONTROL(x) ((x & 0x1) << 42)
/* IA32_HWP_STATUS */
#define HWP_GUARANTEED_CHANGE(x) (x & 0x1)
#define HWP_EXCURSION_TO_MINIMUM(x) (x & 0x4)
/* IA32_HWP_INTERRUPT */
#define HWP_CHANGE_TO_GUARANTEED_INT(x) (x & 0x1)
#define HWP_EXCURSION_TO_MINIMUM_INT(x) (x & 0x2)
#define MSR_AMD64_MC0_MASK 0xc0010044
#define MSR_IA32_MCx_CTL(x) (MSR_IA32_MC0_CTL + 4*(x))
@ -345,6 +384,8 @@
#define MSR_IA32_TEMPERATURE_TARGET 0x000001a2
#define MSR_MISC_PWR_MGMT 0x000001aa
#define MSR_IA32_ENERGY_PERF_BIAS 0x000001b0
#define ENERGY_PERF_BIAS_PERFORMANCE 0
#define ENERGY_PERF_BIAS_NORMAL 6

100
drivers/cpufreq/intel_pstate.c
View File

@ -137,6 +137,7 @@ struct cpu_defaults {
static struct pstate_adjust_policy pid_params;
static struct pstate_funcs pstate_funcs;
static int hwp_active;
struct perf_limits {
int no_turbo;
@ -244,6 +245,34 @@ static inline void update_turbo_state(void)
cpu->pstate.max_pstate == cpu->pstate.turbo_pstate);
}
#define PCT_TO_HWP(x) (x * 255 / 100)
static void intel_pstate_hwp_set(void)
{
int min, max, cpu;
u64 value, freq;
get_online_cpus();
for_each_online_cpu(cpu) {
rdmsrl_on_cpu(cpu, MSR_HWP_REQUEST, &value);
min = PCT_TO_HWP(limits.min_perf_pct);
value &= ~HWP_MIN_PERF(~0L);
value |= HWP_MIN_PERF(min);
max = PCT_TO_HWP(limits.max_perf_pct);
if (limits.no_turbo) {
rdmsrl( MSR_HWP_CAPABILITIES, freq);
max = HWP_GUARANTEED_PERF(freq);
}
value &= ~HWP_MAX_PERF(~0L);
value |= HWP_MAX_PERF(max);
wrmsrl_on_cpu(cpu, MSR_HWP_REQUEST, value);
}
put_online_cpus();
}
/************************** debugfs begin ************************/
static int pid_param_set(void *data, u64 val)
{
@ -279,6 +308,8 @@ static void __init intel_pstate_debug_expose_params(void)
struct dentry *debugfs_parent;
int i = 0;
if (hwp_active)
return;
debugfs_parent = debugfs_create_dir("pstate_snb", NULL);
if (IS_ERR_OR_NULL(debugfs_parent))
return;
@ -329,8 +360,12 @@ static ssize_t store_no_turbo(struct kobject *a, struct attribute *b,
pr_warn("Turbo disabled by BIOS or unavailable on processor\n");
return -EPERM;
}
limits.no_turbo = clamp_t(int, input, 0, 1);
if (hwp_active)
intel_pstate_hwp_set();
return count;
}
@ -348,6 +383,8 @@ static ssize_t store_max_perf_pct(struct kobject *a, struct attribute *b,
limits.max_perf_pct = min(limits.max_policy_pct, limits.max_sysfs_pct);
limits.max_perf = div_fp(int_tofp(limits.max_perf_pct), int_tofp(100));
if (hwp_active)
intel_pstate_hwp_set();
return count;
}
@ -363,6 +400,8 @@ static ssize_t store_min_perf_pct(struct kobject *a, struct attribute *b,
limits.min_perf_pct = clamp_t(int, input, 0 , 100);
limits.min_perf = div_fp(int_tofp(limits.min_perf_pct), int_tofp(100));
if (hwp_active)
intel_pstate_hwp_set();
return count;
}
@ -395,8 +434,16 @@ static void __init intel_pstate_sysfs_expose_params(void)
rc = sysfs_create_group(intel_pstate_kobject, &intel_pstate_attr_group);
BUG_ON(rc);
}
/************************** sysfs end ************************/
static void intel_pstate_hwp_enable(void)
{
hwp_active++;
pr_info("intel_pstate HWP enabled\n");
wrmsrl( MSR_PM_ENABLE, 0x1);
}
static int byt_get_min_pstate(void)
{
u64 value;
@ -648,6 +695,14 @@ static inline void intel_pstate_sample(struct cpudata *cpu)
cpu->prev_mperf = mperf;
}
static inline void intel_hwp_set_sample_time(struct cpudata *cpu)
{
int delay;
delay = msecs_to_jiffies(50);
mod_timer_pinned(&cpu->timer, jiffies + delay);
}
static inline void intel_pstate_set_sample_time(struct cpudata *cpu)
{
int delay;
@ -694,6 +749,14 @@ static inline void intel_pstate_adjust_busy_pstate(struct cpudata *cpu)
intel_pstate_set_pstate(cpu, cpu->pstate.current_pstate - ctl);
}
static void intel_hwp_timer_func(unsigned long __data)
{
struct cpudata *cpu = (struct cpudata *) __data;
intel_pstate_sample(cpu);
intel_hwp_set_sample_time(cpu);
}
static void intel_pstate_timer_func(unsigned long __data)
{
struct cpudata *cpu = (struct cpudata *) __data;
@ -737,6 +800,11 @@ static const struct x86_cpu_id intel_pstate_cpu_ids[] = {
};
MODULE_DEVICE_TABLE(x86cpu, intel_pstate_cpu_ids);
static const struct x86_cpu_id intel_pstate_cpu_oob_ids[] = {
ICPU(0x56, core_params),
{}
};
static int intel_pstate_init_cpu(unsigned int cpunum)
{
struct cpudata *cpu;
@ -753,9 +821,14 @@ static int intel_pstate_init_cpu(unsigned int cpunum)
intel_pstate_get_cpu_pstates(cpu);
init_timer_deferrable(&cpu->timer);
cpu->timer.function = intel_pstate_timer_func;
cpu->timer.data = (unsigned long)cpu;
cpu->timer.expires = jiffies + HZ/100;
if (!hwp_active)
cpu->timer.function = intel_pstate_timer_func;
else
cpu->timer.function = intel_hwp_timer_func;
intel_pstate_busy_pid_reset(cpu);
intel_pstate_sample(cpu);
@ -792,6 +865,7 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy)
limits.no_turbo = 0;
return 0;
}
limits.min_perf_pct = (policy->min * 100) / policy->cpuinfo.max_freq;
limits.min_perf_pct = clamp_t(int, limits.min_perf_pct, 0 , 100);
limits.min_perf = div_fp(int_tofp(limits.min_perf_pct), int_tofp(100));
@ -801,6 +875,9 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy)
limits.max_perf_pct = min(limits.max_policy_pct, limits.max_sysfs_pct);
limits.max_perf = div_fp(int_tofp(limits.max_perf_pct), int_tofp(100));
if (hwp_active)
intel_pstate_hwp_set();
return 0;
}
@ -823,6 +900,9 @@ static void intel_pstate_stop_cpu(struct cpufreq_policy *policy)
pr_info("intel_pstate CPU %d exiting\n", cpu_num);
del_timer_sync(&all_cpu_data[cpu_num]->timer);
if (hwp_active)
return;
intel_pstate_set_pstate(cpu, cpu->pstate.min_pstate);
}
@ -866,6 +946,7 @@ static struct cpufreq_driver intel_pstate_driver = {
};
static int __initdata no_load;
static int __initdata no_hwp;
static int intel_pstate_msrs_not_valid(void)
{
@ -959,6 +1040,15 @@ static bool intel_pstate_platform_pwr_mgmt_exists(void)
{
struct acpi_table_header hdr;
struct hw_vendor_info *v_info;
const struct x86_cpu_id *id;
u64 misc_pwr;
id = x86_match_cpu(intel_pstate_cpu_oob_ids);
if (id) {
rdmsrl(MSR_MISC_PWR_MGMT, misc_pwr);
if ( misc_pwr & (1 << 8))
return true;
}
if (acpi_disabled ||
ACPI_FAILURE(acpi_get_table_header(ACPI_SIG_FADT, 0, &hdr)))
@ -982,6 +1072,7 @@ static int __init intel_pstate_init(void)
int cpu, rc = 0;
const struct x86_cpu_id *id;
struct cpu_defaults *cpu_info;
struct cpuinfo_x86 *c = &boot_cpu_data;
if (no_load)
return -ENODEV;
@ -1011,6 +1102,9 @@ static int __init intel_pstate_init(void)
if (!all_cpu_data)
return -ENOMEM;
if (cpu_has(c,X86_FEATURE_HWP) && !no_hwp)
intel_pstate_hwp_enable();
rc = cpufreq_register_driver(&intel_pstate_driver);
if (rc)
goto out;
@ -1041,6 +1135,8 @@ static int __init intel_pstate_setup(char *str)
if (!strcmp(str, "disable"))
no_load = 1;
if (!strcmp(str, "no_hwp"))
no_hwp = 1;
return 0;
}
early_param("intel_pstate", intel_pstate_setup);