[PATCH v6 2/6] 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.

Reported-by: Artem S. Tashkinov" <aros@xxxxxxx>
Cc: Oleksandr Natalenko <oleksandr@xxxxxxxxxxxxxx>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217931
Signed-off-by: Perry Yuan <Perry.Yuan@xxxxxxx>
---
 drivers/cpufreq/amd-pstate.c | 39 +++++++++++++++++++++++++++---------
 include/linux/amd-pstate.h   | 13 ++++++++++++
 2 files changed, 42 insertions(+), 10 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 59a2db225d98..81787f83c906 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -68,6 +68,8 @@ static int cppc_state = AMD_PSTATE_UNDEFINED;
 static bool cppc_enabled;
 static bool amd_pstate_prefcore = true;
 static struct quirk_entry *quirks;
+struct amd_pstate_global_params amd_pstate_global_params;
+EXPORT_SYMBOL_GPL(amd_pstate_global_params);
 
 /*
  * AMD Energy Preference Performance (EPP)
@@ -665,18 +667,27 @@ static int amd_pstate_set_boost(struct cpufreq_policy *policy, int state)
 	return 0;
 }
 
-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_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;
+	amd_pstate_global_params.cpb_supported = !(boost_val & MSR_K7_HWCR_CPB_DIS);
+
+	if (amd_pstate_global_params.cpb_supported) {
+		cpudata->boost_supported = true;
+		current_pstate_driver->boost_enabled = true;
+	}
 
-	cpudata->boost_supported = true;
-	current_pstate_driver->boost_enabled = true;
+	amd_pstate_global_params.cpb_boost = amd_pstate_global_params.cpb_supported;
+
+	return ret;
 }
 
 static void amd_perf_ctl_reset(unsigned int cpu)
@@ -900,6 +911,11 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
 
 	amd_pstate_init_prefcore(cpudata);
 
+	/* initialize cpu cores boot state */
+	ret = amd_pstate_boost_init(cpudata);
+	if (ret)
+		goto free_cpudata1;
+
 	ret = amd_pstate_init_perf(cpudata);
 	if (ret)
 		goto free_cpudata1;
@@ -956,7 +972,6 @@ 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;
 
@@ -1363,6 +1378,11 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
 
 	amd_pstate_init_prefcore(cpudata);
 
+	/* initialize cpu cores boot state */
+	ret = amd_pstate_boost_init(cpudata);
+	if (ret)
+		goto free_cpudata1;
+
 	ret = amd_pstate_init_perf(cpudata);
 	if (ret)
 		goto free_cpudata1;
@@ -1417,7 +1437,6 @@ 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 6b832153a126..c5e41de65f70 100644
--- a/include/linux/amd-pstate.h
+++ b/include/linux/amd-pstate.h
@@ -134,4 +134,17 @@ struct quirk_entry {
 	u32 lowest_freq;
 };
 
+/**
+ * struct amd_pstate_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 amd_pstate_global_params {
+	bool cpb_boost;
+	bool cpb_supported;
+};
+
+extern struct amd_pstate_global_params amd_pstate_global_params;
+
 #endif /* _LINUX_AMD_PSTATE_H */
-- 
2.34.1