Merge tag 'amd-pstate-v6.16-2025-05-08' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/superm1/linux

Merge amd-pstate content for 6.16 (5/8/25) from Mario Limonciello:

 - Add support for a new feature on some BIOS that allows setting
   "lowest CPU minimum frequency".

 - Fix the amd-pstate-ut unit tests to restore system settings when
   done.

* tag 'amd-pstate-v6.16-2025-05-08' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/superm1/linux:
  amd-pstate-ut: Reset amd-pstate driver mode after running selftests
  cpufreq/amd-pstate: Add support for the "Requested CPU Min frequency" BIOS option
  cpufreq/amd-pstate: Add offline, online and suspend callbacks for amd_pstate_driver
  cpufreq/amd-pstate: Move max_perf limiting in amd_pstate_update

Author: rafaeljw

drivers/cpufreq/amd-pstate-ut.c

@@ -242,6 +242,8 @@ static int amd_pstate_set_mode(enum amd_pstate_mode mode)
 static int amd_pstate_ut_check_driver(u32 index)
 {
 	enum amd_pstate_mode mode1, mode2 = AMD_PSTATE_DISABLE;
+	enum amd_pstate_mode orig_mode = amd_pstate_get_status();
+	int ret;
 
 	for (mode1 = AMD_PSTATE_DISABLE; mode1 < AMD_PSTATE_MAX; mode1++) {
 		int ret = amd_pstate_set_mode(mode1);
@@ -251,16 +253,19 @@ static int amd_pstate_ut_check_driver(u32 index)
 			if (mode1 == mode2)
 				continue;
 			ret = amd_pstate_set_mode(mode2);
-			if (ret) {
-				pr_err("%s: failed to update status for %s->%s\n", __func__,
-					amd_pstate_get_mode_string(mode1),
-					amd_pstate_get_mode_string(mode2));
-				return ret;
-			}
+			if (ret)
+				goto out;
 		}
 	}
 
-	return 0;
+out:
+	if (ret)
+		pr_warn("%s: failed to update status for %s->%s: %d\n", __func__,
+			amd_pstate_get_mode_string(mode1),
+			amd_pstate_get_mode_string(mode2), ret);
+
+	amd_pstate_set_mode(orig_mode);
+	return ret;
 }
 
 static int __init amd_pstate_ut_init(void)

drivers/cpufreq/amd-pstate.c

@@ -389,7 +389,8 @@ static inline int amd_pstate_cppc_enable(struct cpufreq_policy *policy)
 static int msr_init_perf(struct amd_cpudata *cpudata)
 {
 	union perf_cached perf = READ_ONCE(cpudata->perf);
-	u64 cap1, numerator;
+	u64 cap1, numerator, cppc_req;
+	u8 min_perf;
 
 	int ret = rdmsrl_safe_on_cpu(cpudata->cpu, MSR_AMD_CPPC_CAP1,
 				     &cap1);
@@ -400,6 +401,22 @@ static int msr_init_perf(struct amd_cpudata *cpudata)
 	if (ret)
 		return ret;
 
+	ret = rdmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_REQ, &cppc_req);
+	if (ret)
+		return ret;
+
+	WRITE_ONCE(cpudata->cppc_req_cached, cppc_req);
+	min_perf = FIELD_GET(AMD_CPPC_MIN_PERF_MASK, cppc_req);
+
+	/*
+	 * Clear out the min_perf part to check if the rest of the MSR is 0, if yes, this is an
+	 * indication that the min_perf value is the one specified through the BIOS option
+	 */
+	cppc_req &= ~(AMD_CPPC_MIN_PERF_MASK);
+
+	if (!cppc_req)
+		perf.bios_min_perf = min_perf;
+
 	perf.highest_perf = numerator;
 	perf.max_limit_perf = numerator;
 	perf.min_limit_perf = FIELD_GET(AMD_CPPC_LOWEST_PERF_MASK, cap1);
@@ -554,6 +571,10 @@ static void amd_pstate_update(struct amd_cpudata *cpudata, u8 min_perf,
 	if (!policy)
 		return;
 
+	/* limit the max perf when core performance boost feature is disabled */
+	if (!cpudata->boost_supported)
+		max_perf = min_t(u8, perf.nominal_perf, max_perf);
+
 	des_perf = clamp_t(u8, des_perf, min_perf, max_perf);
 
 	policy->cur = perf_to_freq(perf, cpudata->nominal_freq, des_perf);
@@ -563,10 +584,6 @@ static void amd_pstate_update(struct amd_cpudata *cpudata, u8 min_perf,
 		des_perf = 0;
 	}
 
-	/* limit the max perf when core performance boost feature is disabled */
-	if (!cpudata->boost_supported)
-		max_perf = min_t(u8, perf.nominal_perf, max_perf);
-
 	if (trace_amd_pstate_perf_enabled() && amd_pstate_sample(cpudata)) {
 		trace_amd_pstate_perf(min_perf, des_perf, max_perf, cpudata->freq,
 			cpudata->cur.mperf, cpudata->cur.aperf, cpudata->cur.tsc,
@@ -580,20 +597,26 @@ static int amd_pstate_verify(struct cpufreq_policy_data *policy_data)
 {
 	/*
 	 * Initialize lower frequency limit (i.e.policy->min) with
-	 * lowest_nonlinear_frequency which is the most energy efficient
-	 * frequency. Override the initial value set by cpufreq core and
-	 * amd-pstate qos_requests.
+	 * lowest_nonlinear_frequency or the min frequency (if) specified in BIOS,
+	 * Override the initial value set by cpufreq core and amd-pstate qos_requests.
 	 */
 	if (policy_data->min == FREQ_QOS_MIN_DEFAULT_VALUE) {
 		struct cpufreq_policy *policy __free(put_cpufreq_policy) =
 					      cpufreq_cpu_get(policy_data->cpu);
 		struct amd_cpudata *cpudata;
+		union perf_cached perf;
 
 		if (!policy)
 			return -EINVAL;
 
 		cpudata = policy->driver_data;
-		policy_data->min = cpudata->lowest_nonlinear_freq;
+		perf = READ_ONCE(cpudata->perf);
+
+		if (perf.bios_min_perf)
+			policy_data->min = perf_to_freq(perf, cpudata->nominal_freq,
+							perf.bios_min_perf);
+		else
+			policy_data->min = cpudata->lowest_nonlinear_freq;
 	}
 
 	cpufreq_verify_within_cpu_limits(policy_data);
@@ -1021,6 +1044,10 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
 static void amd_pstate_cpu_exit(struct cpufreq_policy *policy)
 {
 	struct amd_cpudata *cpudata = policy->driver_data;
+	union perf_cached perf = READ_ONCE(cpudata->perf);
+
+	/* Reset CPPC_REQ MSR to the BIOS value */
+	amd_pstate_update_perf(policy, perf.bios_min_perf, 0U, 0U, 0U, false);
 
 	freq_qos_remove_request(&cpudata->req[1]);
 	freq_qos_remove_request(&cpudata->req[0]);
@@ -1302,6 +1329,12 @@ static ssize_t amd_pstate_show_status(char *buf)
 	return sysfs_emit(buf, "%s\n", amd_pstate_mode_string[cppc_state]);
 }
 
+int amd_pstate_get_status(void)
+{
+	return cppc_state;
+}
+EXPORT_SYMBOL_GPL(amd_pstate_get_status);
+
 int amd_pstate_update_status(const char *buf, size_t size)
 {
 	int mode_idx;
@@ -1416,7 +1449,6 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
 	struct amd_cpudata *cpudata;
 	union perf_cached perf;
 	struct device *dev;
-	u64 value;
 	int ret;
 
 	/*
@@ -1481,12 +1513,6 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
 		cpudata->epp_default = AMD_CPPC_EPP_BALANCE_PERFORMANCE;
 	}
 
-	if (cpu_feature_enabled(X86_FEATURE_CPPC)) {
-		ret = rdmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_REQ, &value);
-		if (ret)
-			return ret;
-		WRITE_ONCE(cpudata->cppc_req_cached, value);
-	}
 	ret = amd_pstate_set_epp(policy, cpudata->epp_default);
 	if (ret)
 		return ret;
@@ -1506,6 +1532,11 @@ static void amd_pstate_epp_cpu_exit(struct cpufreq_policy *policy)
 	struct amd_cpudata *cpudata = policy->driver_data;
 
 	if (cpudata) {
+		union perf_cached perf = READ_ONCE(cpudata->perf);
+
+		/* Reset CPPC_REQ MSR to the BIOS value */
+		amd_pstate_update_perf(policy, perf.bios_min_perf, 0U, 0U, 0U, false);
+
 		kfree(cpudata);
 		policy->driver_data = NULL;
 	}
@@ -1556,21 +1587,38 @@ static int amd_pstate_epp_set_policy(struct cpufreq_policy *policy)
 	return 0;
 }
 
-static int amd_pstate_epp_cpu_online(struct cpufreq_policy *policy)
+static int amd_pstate_cpu_online(struct cpufreq_policy *policy)
 {
-	pr_debug("AMD CPU Core %d going online\n", policy->cpu);
-
 	return amd_pstate_cppc_enable(policy);
 }
 
-static int amd_pstate_epp_cpu_offline(struct cpufreq_policy *policy)
+static int amd_pstate_cpu_offline(struct cpufreq_policy *policy)
 {
-	return 0;
+	struct amd_cpudata *cpudata = policy->driver_data;
+	union perf_cached perf = READ_ONCE(cpudata->perf);
+
+	/*
+	 * Reset CPPC_REQ MSR to the BIOS value, this will allow us to retain the BIOS specified
+	 * min_perf value across kexec reboots. If this CPU is just onlined normally after this, the
+	 * limits, epp and desired perf will get reset to the cached values in cpudata struct
+	 */
+	return amd_pstate_update_perf(policy, perf.bios_min_perf, 0U, 0U, 0U, false);
 }
 
-static int amd_pstate_epp_suspend(struct cpufreq_policy *policy)
+static int amd_pstate_suspend(struct cpufreq_policy *policy)
 {
 	struct amd_cpudata *cpudata = policy->driver_data;
+	union perf_cached perf = READ_ONCE(cpudata->perf);
+	int ret;
+
+	/*
+	 * Reset CPPC_REQ MSR to the BIOS value, this will allow us to retain the BIOS specified
+	 * min_perf value across kexec reboots. If this CPU is just resumed back without kexec,
+	 * the limits, epp and desired perf will get reset to the cached values in cpudata struct
+	 */
+	ret = amd_pstate_update_perf(policy, perf.bios_min_perf, 0U, 0U, 0U, false);
+	if (ret)
+		return ret;
 
 	/* invalidate to ensure it's rewritten during resume */
 	cpudata->cppc_req_cached = 0;
@@ -1581,6 +1629,17 @@ static int amd_pstate_epp_suspend(struct cpufreq_policy *policy)
 	return 0;
 }
 
+static int amd_pstate_resume(struct cpufreq_policy *policy)
+{
+	struct amd_cpudata *cpudata = policy->driver_data;
+	union perf_cached perf = READ_ONCE(cpudata->perf);
+	int cur_perf = freq_to_perf(perf, cpudata->nominal_freq, policy->cur);
+
+	/* Set CPPC_REQ to last sane value until the governor updates it */
+	return amd_pstate_update_perf(policy, perf.min_limit_perf, cur_perf, perf.max_limit_perf,
+				      0U, false);
+}
+
 static int amd_pstate_epp_resume(struct cpufreq_policy *policy)
 {
 	struct amd_cpudata *cpudata = policy->driver_data;
@@ -1606,6 +1665,10 @@ static struct cpufreq_driver amd_pstate_driver = {
 	.fast_switch    = amd_pstate_fast_switch,
 	.init		= amd_pstate_cpu_init,
 	.exit		= amd_pstate_cpu_exit,
+	.online		= amd_pstate_cpu_online,
+	.offline	= amd_pstate_cpu_offline,
+	.suspend	= amd_pstate_suspend,
+	.resume		= amd_pstate_resume,
 	.set_boost	= amd_pstate_set_boost,
 	.update_limits	= amd_pstate_update_limits,
 	.name		= "amd-pstate",
@@ -1618,9 +1681,9 @@ static struct cpufreq_driver amd_pstate_epp_driver = {
 	.setpolicy	= amd_pstate_epp_set_policy,
 	.init		= amd_pstate_epp_cpu_init,
 	.exit		= amd_pstate_epp_cpu_exit,
-	.offline	= amd_pstate_epp_cpu_offline,
-	.online		= amd_pstate_epp_cpu_online,
-	.suspend	= amd_pstate_epp_suspend,
+	.offline	= amd_pstate_cpu_offline,
+	.online		= amd_pstate_cpu_online,
+	.suspend	= amd_pstate_suspend,
 	.resume		= amd_pstate_epp_resume,
 	.update_limits	= amd_pstate_update_limits,
 	.set_boost	= amd_pstate_set_boost,

drivers/cpufreq/amd-pstate.h

@@ -30,6 +30,7 @@
  * @lowest_perf: the absolute lowest performance level of the processor
  * @min_limit_perf: Cached value of the performance corresponding to policy->min
  * @max_limit_perf: Cached value of the performance corresponding to policy->max
+ * @bios_min_perf: Cached perf value corresponding to the "Requested CPU Min Frequency" BIOS option
  */
 union perf_cached {
 	struct {
@@ -39,6 +40,7 @@ union perf_cached {
 		u8	lowest_perf;
 		u8	min_limit_perf;
 		u8	max_limit_perf;
+		u8	bios_min_perf;
 	};
 	u64	val;
 };
@@ -119,6 +121,7 @@ enum amd_pstate_mode {
 	AMD_PSTATE_MAX,
 };
 const char *amd_pstate_get_mode_string(enum amd_pstate_mode mode);
+int amd_pstate_get_status(void);
 int amd_pstate_update_status(const char *buf, size_t size);
 
 #endif /* _LINUX_AMD_PSTATE_H */