x86 thermal: Disable power limit notification interrupt by default

The package power limit notification interrupt is primarily for
system diagnosis, and should not be blindly enabled on every
system by default -- particuarly since Linux does nothing in the
handler except count how many times it has been called...

Add a new kernel cmdline parameter "int_pln_enable" for situations where
users want to oberve these events via existing system counters:

$ grep TRM /proc/interrupts

$ grep . /sys/devices/system/cpu/cpu*/thermal_throttle/*

https://bugzilla.kernel.org/show_bug.cgi?id=36182

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 26 insertions, 8 deletions

diff --git a/arch/x86/kernel/cpu/mcheck/therm_throt.c b/arch/x86/kernel/cpu/mcheck/therm_throt.c
index 68fa89043abf..f7feb2e9ed17 100644
--- a/arch/x86/kernel/cpu/mcheck/therm_throt.c
+++ b/arch/x86/kernel/cpu/mcheck/therm_throt.c
@@ -210,6 +210,15 @@ static int thresh_event_valid(int event)
         return 1;
 }
 
+static bool int_pln_enable;
+static int __init int_pln_enable_setup(char *s)
+{
+        int_pln_enable = true;
+
+        return 1;
+}
+__setup("int_pln_enable", int_pln_enable_setup);
+
 #ifdef CONFIG_SYSFS
 /* Add/Remove thermal_throttle interface for CPU device: */
 static __cpuinit int thermal_throttle_add_dev(struct device *dev,
@@ -222,7 +231,7 @@ static __cpuinit int thermal_throttle_add_dev(struct device *dev,
         if (err)
                 return err;
 
-        if (cpu_has(c, X86_FEATURE_PLN))
+        if (cpu_has(c, X86_FEATURE_PLN) && int_pln_enable)
                 err = sysfs_add_file_to_group(&dev->kobj,
                                               &dev_attr_core_power_limit_count.attr,
                                               thermal_attr_group.name);
@@ -230,7 +239,7 @@ static __cpuinit int thermal_throttle_add_dev(struct device *dev,
                 err = sysfs_add_file_to_group(&dev->kobj,
                                               &dev_attr_package_throttle_count.attr,
                                               thermal_attr_group.name);
-                if (cpu_has(c, X86_FEATURE_PLN))
+                if (cpu_has(c, X86_FEATURE_PLN) && int_pln_enable)
                         err = sysfs_add_file_to_group(&dev->kobj,
                                         &dev_attr_package_power_limit_count.attr,
                                         thermal_attr_group.name);
@@ -343,7 +352,7 @@ static void intel_thermal_interrupt(void)
                                 CORE_LEVEL) != 0)
                 mce_log_therm_throt_event(msr_val);
 
-        if (this_cpu_has(X86_FEATURE_PLN))
+        if (this_cpu_has(X86_FEATURE_PLN) && int_pln_enable)
                 therm_throt_process(msr_val & THERM_STATUS_POWER_LIMIT,
                                         POWER_LIMIT_EVENT,
                                         CORE_LEVEL);
@@ -353,7 +362,7 @@ static void intel_thermal_interrupt(void)
                 therm_throt_process(msr_val & PACKAGE_THERM_STATUS_PROCHOT,
                                         THERMAL_THROTTLING_EVENT,
                                         PACKAGE_LEVEL);
-                if (this_cpu_has(X86_FEATURE_PLN))
+                if (this_cpu_has(X86_FEATURE_PLN) && int_pln_enable)
                         therm_throt_process(msr_val &
                                         PACKAGE_THERM_STATUS_POWER_LIMIT,
                                         POWER_LIMIT_EVENT,
@@ -461,9 +470,13 @@ void intel_init_thermal(struct cpuinfo_x86 *c)
         apic_write(APIC_LVTTHMR, h);
 
         rdmsr(MSR_IA32_THERM_INTERRUPT, l, h);
-        if (cpu_has(c, X86_FEATURE_PLN))
+        if (cpu_has(c, X86_FEATURE_PLN) && !int_pln_enable)
+                wrmsr(MSR_IA32_THERM_INTERRUPT,
+                        (l | (THERM_INT_LOW_ENABLE
+                        | THERM_INT_HIGH_ENABLE)) & ~THERM_INT_PLN_ENABLE, h);
+        else if (cpu_has(c, X86_FEATURE_PLN) && int_pln_enable)
                 wrmsr(MSR_IA32_THERM_INTERRUPT,
-                      l | (THERM_INT_LOW_ENABLE
+                        l | (THERM_INT_LOW_ENABLE
                         | THERM_INT_HIGH_ENABLE | THERM_INT_PLN_ENABLE), h);
         else
                 wrmsr(MSR_IA32_THERM_INTERRUPT,
@@ -471,9 +484,14 @@ void intel_init_thermal(struct cpuinfo_x86 *c)
 
         if (cpu_has(c, X86_FEATURE_PTS)) {
                 rdmsr(MSR_IA32_PACKAGE_THERM_INTERRUPT, l, h);
-                if (cpu_has(c, X86_FEATURE_PLN))
+                if (cpu_has(c, X86_FEATURE_PLN) && !int_pln_enable)
                         wrmsr(MSR_IA32_PACKAGE_THERM_INTERRUPT,
-                              l | (PACKAGE_THERM_INT_LOW_ENABLE
+                                (l | (PACKAGE_THERM_INT_LOW_ENABLE
+                                | PACKAGE_THERM_INT_HIGH_ENABLE))
+                                & ~PACKAGE_THERM_INT_PLN_ENABLE, h);
+                else if (cpu_has(c, X86_FEATURE_PLN) && int_pln_enable)
+                        wrmsr(MSR_IA32_PACKAGE_THERM_INTERRUPT,
+                                l | (PACKAGE_THERM_INT_LOW_ENABLE
                                 | PACKAGE_THERM_INT_HIGH_ENABLE
                                 | PACKAGE_THERM_INT_PLN_ENABLE), h);
                 else