[PATCH 2/7] cpufreq: amd-pstate: initialize new core precision boost state

[Perry Yuan]

From: Perry Yuan <Perry.Yuan@xxxxxxx>

Add gloal global_params to represent current CPU Performance Boost(cpb)
state for cpu frequency scaling, both active and passive modes all can
support CPU cores frequency boosting control which is based on the BIOS
setting, while BIOS turn on the "Core Performance Boost", it will
allow OS control each core highest perf limitation from OS side.

If core performance boost is disabled while a core is in a boosted P-state,
the core transitions to the highest performance non-boosted P-state,
that is the same as the nominal frequency limit.

Issue: https://bugzilla.kernel.org/show_bug.cgi?id=217931
Reported-by: Artem S. Tashkinov" <aros@xxxxxxx>
Signed-off-by: Perry Yuan <Perry.Yuan@xxxxxxx>
---
 drivers/cpufreq/amd-pstate.c | 46 ++++++++++++++++++++++++++++--------
 include/linux/amd-pstate.h   |  1 -
 2 files changed, 36 insertions(+), 11 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 8f308f56ade6..0dc9124140d4 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -65,6 +65,19 @@ static struct cpufreq_driver amd_pstate_epp_driver;
 static int cppc_state = AMD_PSTATE_UNDEFINED;
 static bool cppc_enabled;
 
+/**
+ * struct global_params - Global parameters, mostly tunable via sysfs.
+ * @cpb_boost:		Whether or not to use boost CPU P-states.
+ * @cpb_supported:	Whether or not CPU boost P-states are available
+ *			based on the MSR_K7_HWCR bit[25] state
+ */
+struct global_params {
+	bool cpb_boost;
+	bool cpb_supported;
+};
+
+static struct global_params global;
+
 /*
  * AMD Energy Preference Performance (EPP)
  * The EPP is used in the CCLK DPM controller to drive
@@ -632,18 +645,27 @@ static int amd_get_lowest_nonlinear_freq(struct amd_cpudata *cpudata)
 	return lowest_nonlinear_freq * 1000;
 }
 
-static void amd_pstate_boost_init(struct amd_cpudata *cpudata)
+static int amd_pstate_boost_init(struct amd_cpudata *cpudata)
 {
-	u32 highest_perf, nominal_perf;
+	u64 boost_state, boost_val;
+	int ret;
 
-	highest_perf = READ_ONCE(cpudata->highest_perf);
-	nominal_perf = READ_ONCE(cpudata->nominal_perf);
+	ret = rdmsrl_on_cpu(cpudata->cpu, MSR_K7_HWCR, &boost_val);
+	if (ret) {
+		pr_err_once("failed to read initial CPU boost state!\n");
+		return ret;
+	}
 
-	if (highest_perf <= nominal_perf)
-		return;
+	boost_state = (boost_val >> 25) & 0x1;
+	if (!boost_state) {
+		global.cpb_supported = true;
+		global.cpb_boost = true;
+	} else {
+		global.cpb_supported = false;
+		global.cpb_boost = false;
+	}
 
-	cpudata->boost_supported = true;
-	current_pstate_driver->boost_enabled = true;
+	return ret;
 }
 
 static void amd_perf_ctl_reset(unsigned int cpu)
@@ -676,6 +698,9 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
 	if (ret)
 		goto free_cpudata1;
 
+	/* initialize cpu cores boot state */
+	amd_pstate_boost_init(cpudata);
+
 	min_freq = amd_get_min_freq(cpudata);
 	max_freq = amd_get_max_freq(cpudata);
 	nominal_freq = amd_get_nominal_freq(cpudata);
@@ -725,7 +750,6 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
 
 	policy->driver_data = cpudata;
 
-	amd_pstate_boost_init(cpudata);
 	if (!current_pstate_driver->adjust_perf)
 		current_pstate_driver->adjust_perf = amd_pstate_adjust_perf;
 
@@ -1093,6 +1117,9 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
 	if (ret)
 		goto free_cpudata1;
 
+	/* initialize cpu cores boot state */
+	amd_pstate_boost_init(cpudata);
+
 	min_freq = amd_get_min_freq(cpudata);
 	max_freq = amd_get_max_freq(cpudata);
 	nominal_freq = amd_get_nominal_freq(cpudata);
@@ -1143,7 +1170,6 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
 			return ret;
 		WRITE_ONCE(cpudata->cppc_cap1_cached, value);
 	}
-	amd_pstate_boost_init(cpudata);
 
 	return 0;
 
diff --git a/include/linux/amd-pstate.h b/include/linux/amd-pstate.h
index 446394f84606..66d939a344b1 100644
--- a/include/linux/amd-pstate.h
+++ b/include/linux/amd-pstate.h
@@ -80,7 +80,6 @@ struct amd_cpudata {
 	struct amd_aperf_mperf prev;
 
 	u64	freq;
-	bool	boost_supported;
 
 	/* EPP feature related attributes*/
 	s16	epp_policy;
-- 
2.34.1