2 files changed, 63 insertions, 1 deletions
diff --git a/src/cpu/intel/common/common.h b/src/cpu/intel/common/common.h
index ef0a5d9044..a29fd2e6b6 100644
--- a/src/cpu/intel/common/common.h
+++ b/src/cpu/intel/common/common.h
@@ -47,4 +47,23 @@ void configure_dca_cap(void);
  */
 void set_energy_perf_bias(u8 policy);
 
+/*
+ * Check energy performance preference and HWP capabilities from Thermal and
+ * Power Management Leaf CPUID.
+ */
+bool check_energy_perf_cap(void);
+
+/*
+ * Set the IA32_HWP_REQUEST Energy-Performance Preference bits on the logical
+ * thread. 0 is a hint to the HWP to prefer performance, and 255 is a hint to
+ * prefer energy efficiency.
+ */
+void set_energy_perf_pref(u8 pref);
+
+/*
+ * Instructs the CPU to use EPP hints. This means that any energy policies set
+ * up in `set_energy_perf_bias` will be ignored afterwards.
+ */
+void enable_energy_perf_pref(void);
+
 #endif
diff --git a/src/cpu/intel/common/common_init.c b/src/cpu/intel/common/common_init.c
index 24e3eeb60b..4d6df845f7 100644
--- a/src/cpu/intel/common/common_init.c
+++ b/src/cpu/intel/common/common_init.c
@@ -5,9 +5,12 @@
 #include <console/console.h>
 #include <cpu/intel/msr.h>
 #include <cpu/x86/msr.h>
+#include <cpu/intel/turbo.h>
 #include "common.h"
 
-#define  CPUID_6_ECX_EPB	(1 << 3)
+#define  CPUID_6_ECX_EPB		(1 << 3)
+#define  CPUID_6_ENGERY_PERF_PREF	(1 << 10)
+#define  CPUID_6_HWP			(1 << 7)
 
 void set_vmx_and_lock(void)
 {
@@ -182,3 +185,43 @@ void set_energy_perf_bias(u8 policy)
 	msr_unset_and_set(IA32_ENERGY_PERF_BIAS, ENERGY_POLICY_MASK, epb);
 	printk(BIOS_DEBUG, "cpu: energy policy set to %u\n", epb);
 }
+
+/*
+ * Check energy performance preference and HWP capabilities from Thermal and
+ * Power Management Leaf CPUID
+ */
+bool check_energy_perf_cap(void)
+{
+	const u32 cap = cpuid_eax(CPUID_LEAF_PM);
+	if (!(cap & CPUID_6_ENGERY_PERF_PREF))
+		return false;
+	if (!(cap & CPUID_6_HWP))
+		return false;
+	return true;
+}
+
+/*
+ * Instructs the CPU to use EPP hints. This means that any energy policies set
+ * up in `set_energy_perf_bias` will be ignored afterwards.
+ */
+void enable_energy_perf_pref(void)
+{
+	msr_t msr = rdmsr(IA32_PM_ENABLE);
+	if (!(msr.lo & HWP_ENABLE)) {
+		/* Package-scoped MSR */
+		printk(BIOS_DEBUG, "HWP_ENABLE: energy-perf preference in favor of energy-perf bias\n");
+		msr_set(IA32_PM_ENABLE, HWP_ENABLE);
+	}
+}
+
+/*
+ * Set the IA32_HWP_REQUEST Energy-Performance Preference bits on the logical
+ * thread. 0 is a hint to the HWP to prefer performance, and 255 is a hint to
+ * prefer energy efficiency.
+ * This function needs to be called when HWP_ENABLE is set.
+*/
+void set_energy_perf_pref(u8 pref)
+{
+	msr_unset_and_set(IA32_HWP_REQUEST, IA32_HWP_REQUEST_EPP_MASK,
+		pref << IA32_HWP_REQUEST_EPP_SHIFT);
+}