cpufreq/amd-pstate: Drop boost_state variable

Currently boost_state is cached for every processor in cpudata structure
and driver boost state is set for every processor.

Both of these aren't necessary as the driver only needs to set once and
the policy stores whether boost is enabled.

Move the driver boost setting to registration and adjust all references
to cached value to pull from the policy instead.

Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Link: https://lore.kernel.org/r/20241209185248.16301-16-mario.limonciello@amd.com
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>

drivers/cpufreq/amd-pstate.c

@@ -316,9 +316,10 @@ static int shmem_set_epp(struct amd_cpudata *cpudata, u32 epp)
 	return ret;
 }
 
-static int amd_pstate_set_energy_pref_index(struct amd_cpudata *cpudata,
-		int pref_index)
+static int amd_pstate_set_energy_pref_index(struct cpufreq_policy *policy,
+					    int pref_index)
 {
+	struct amd_cpudata *cpudata = policy->driver_data;
 	int epp;
 
 	if (!pref_index)
@@ -336,7 +337,7 @@ static int amd_pstate_set_energy_pref_index(struct amd_cpudata *cpudata,
 					  epp,
 					  FIELD_GET(AMD_CPPC_MIN_PERF_MASK, cpudata->cppc_req_cached),
 					  FIELD_GET(AMD_CPPC_MAX_PERF_MASK, cpudata->cppc_req_cached),
-					  cpudata->boost_state);
+					  policy->boost_enabled);
 	}
 
 	return amd_pstate_set_epp(cpudata, epp);
@@ -746,7 +747,6 @@ static int amd_pstate_set_boost(struct cpufreq_policy *policy, int state)
 	guard(mutex)(&amd_pstate_driver_lock);
 
 	ret = amd_pstate_cpu_boost_update(policy, state);
-	WRITE_ONCE(cpudata->boost_state, !ret ? state : false);
 	policy->boost_enabled = !ret ? state : false;
 	refresh_frequency_limits(policy);
 
@@ -768,9 +768,6 @@ static int amd_pstate_init_boost_support(struct amd_cpudata *cpudata)
 		goto exit_err;
 	}
 
-	/* at least one CPU supports CPB, even if others fail later on to set up */
-	current_pstate_driver->boost_enabled = true;
-
 	ret = rdmsrl_on_cpu(cpudata->cpu, MSR_K7_HWCR, &boost_val);
 	if (ret) {
 		pr_err_once("failed to read initial CPU boost state!\n");
@@ -1176,7 +1173,6 @@ static ssize_t show_energy_performance_available_preferences(
 static ssize_t store_energy_performance_preference(
 		struct cpufreq_policy *policy, const char *buf, size_t count)
 {
-	struct amd_cpudata *cpudata = policy->driver_data;
 	char str_preference[21];
 	ssize_t ret;
 
@@ -1190,7 +1186,7 @@ static ssize_t store_energy_performance_preference(
 
 	guard(mutex)(&amd_pstate_limits_lock);
 
-	ret = amd_pstate_set_energy_pref_index(cpudata, ret);
+	ret = amd_pstate_set_energy_pref_index(policy, ret);
 
 	return ret ? ret : count;
 }
@@ -1265,6 +1261,9 @@ static int amd_pstate_register_driver(int mode)
 		return ret;
 	}
 
+	/* at least one CPU supports CPB */
+	current_pstate_driver->boost_enabled = cpu_feature_enabled(X86_FEATURE_CPB);
+
 	ret = cpufreq_register_driver(current_pstate_driver);
 	if (ret) {
 		amd_pstate_driver_cleanup();
@@ -1604,8 +1603,9 @@ static int amd_pstate_epp_set_policy(struct cpufreq_policy *policy)
 	return 0;
 }
 
-static int amd_pstate_epp_reenable(struct amd_cpudata *cpudata)
+static int amd_pstate_epp_reenable(struct cpufreq_policy *policy)
 {
+	struct amd_cpudata *cpudata = policy->driver_data;
 	u64 max_perf;
 	int ret;
 
@@ -1619,7 +1619,7 @@ static int amd_pstate_epp_reenable(struct amd_cpudata *cpudata)
 		trace_amd_pstate_epp_perf(cpudata->cpu, cpudata->highest_perf,
 					  cpudata->epp_cached,
 					  FIELD_GET(AMD_CPPC_MIN_PERF_MASK, cpudata->cppc_req_cached),
-					  max_perf, cpudata->boost_state);
+					  max_perf, policy->boost_enabled);
 	}
 
 	return amd_pstate_update_perf(cpudata, 0, 0, max_perf, cpudata->epp_cached, false);
@@ -1632,7 +1632,7 @@ static int amd_pstate_epp_cpu_online(struct cpufreq_policy *policy)
 
 	pr_debug("AMD CPU Core %d going online\n", cpudata->cpu);
 
-	ret = amd_pstate_epp_reenable(cpudata);
+	ret = amd_pstate_epp_reenable(policy);
 	if (ret)
 		return ret;
 	cpudata->suspended = false;
@@ -1690,7 +1690,7 @@ static int amd_pstate_epp_resume(struct cpufreq_policy *policy)
 		guard(mutex)(&amd_pstate_limits_lock);
 
 		/* enable amd pstate from suspend state*/
-		amd_pstate_epp_reenable(cpudata);
+		amd_pstate_epp_reenable(policy);
 
 		cpudata->suspended = false;
 	}

drivers/cpufreq/amd-pstate.h

@@ -98,7 +98,6 @@ struct amd_cpudata {
 	u64	cppc_cap1_cached;
 	bool	suspended;
 	s16	epp_default;
-	bool	boost_state;
 };
 
 /*