[PATCH v3 9/9] cpufreq/amd-pstate-ut: Add unit test for CPPC Performance Priority

[K Prateek Nayak <kprateek.nayak@amd.com>]

Add a unit test for CPPC Performance Priority that modifies the floor
perf and confirms if the modification was successful similar to the
energy_performance_preference unit test.

On platforms that do not support X86_FEATURE_CPPC_PERF_PRIO, the test
returns -EOPNOTSUPP and amd_pstate_ut_check_floor_freq is marked as
"skipped".

Suggested-by: Kalpana Shetty <kalpana.shetty@amd.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
---
changelog v2..v3:

o Collected tag from Mario. (Thanks a ton!)
---
 drivers/cpufreq/amd-pstate-ut.c | 86 ++++++++++++++++++++++++++++++++-
 drivers/cpufreq/amd-pstate.c    |  7 +--
 drivers/cpufreq/amd-pstate.h    |  2 +
 3 files changed, 90 insertions(+), 5 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate-ut.c b/drivers/cpufreq/amd-pstate-ut.c
index b432eae1dd52..e23773680e05 100644
--- a/drivers/cpufreq/amd-pstate-ut.c
+++ b/drivers/cpufreq/amd-pstate-ut.c
@@ -59,6 +59,7 @@ static int amd_pstate_ut_check_freq(u32 index);
 static int amd_pstate_ut_epp(u32 index);
 static int amd_pstate_ut_check_driver(u32 index);
 static int amd_pstate_ut_check_freq_attrs(u32 index);
+static int amd_pstate_ut_check_floor_freq(u32 index);
 
 static struct amd_pstate_ut_struct amd_pstate_ut_cases[] = {
 	{"amd_pstate_ut_acpi_cpc_valid",    amd_pstate_ut_acpi_cpc_valid   },
@@ -68,6 +69,7 @@ static struct amd_pstate_ut_struct amd_pstate_ut_cases[] = {
 	{"amd_pstate_ut_epp",               amd_pstate_ut_epp              },
 	{"amd_pstate_ut_check_driver",      amd_pstate_ut_check_driver     },
 	{"amd_pstate_ut_check_freq_attrs",  amd_pstate_ut_check_freq_attrs },
+	{"amd_pstate_ut_check_floor_freq",  amd_pstate_ut_check_floor_freq },
 };
 
 static bool test_in_list(const char *list, const char *name)
@@ -560,6 +562,80 @@ static int amd_pstate_ut_check_freq_attrs(u32 index)
 	return ret;
 }
 
+static int amd_pstate_ut_check_floor_freq(u32 index)
+{
+	struct cpufreq_policy *policy __free(put_cpufreq_policy) = NULL;
+	char *buf __free(cleanup_page) = NULL;
+	unsigned int orig_floor_freq;
+	unsigned int floor_freq;
+	int ret, cpu = 0;
+
+	if (!cpu_feature_enabled(X86_FEATURE_CPPC_PERF_PRIO))
+		return -EOPNOTSUPP;
+
+	policy = cpufreq_cpu_get(cpu);
+	if (!policy)
+		return -ENODEV;
+
+	buf = (char *)__get_free_page(GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	guard(rwsem_write)(&policy->rwsem);
+
+	if (!policy->driver_data)
+		return -ENODEV;
+
+	/* Retrieve original floor frequency */
+	memset(buf, 0, PAGE_SIZE);
+	ret = show_amd_pstate_floor_freq(policy, buf);
+	if (ret < 0)
+		return ret;
+
+	ret = kstrtou32(buf, 0, &orig_floor_freq);
+	if (ret)
+		return ret;
+
+	memset(buf, 0, PAGE_SIZE);
+	snprintf(buf, PAGE_SIZE, "%u", policy->cpuinfo.min_freq);
+
+	/* Set floor frequency to cpuinfo.min_freq */
+	ret = store_amd_pstate_floor_freq(policy, buf, strlen(buf));
+	if (ret < 0) {
+		pr_err("Failed to set floor frequency to %s\n", buf);
+		return ret;
+	}
+
+	memset(buf, 0, PAGE_SIZE);
+	ret = show_amd_pstate_floor_freq(policy, buf);
+	if (ret < 0)
+		return ret;
+
+	strreplace(buf, '\n', '\0');
+	ret = kstrtou32(buf, 0, &floor_freq);
+	if (ret)
+		return ret;
+
+	/* Confirm sysfs reflects the change correctly. */
+	if (floor_freq != policy->cpuinfo.min_freq) {
+		pr_err("Floor frequency value mismatch: %u != %u\n",
+		       floor_freq, policy->cpuinfo.min_freq);
+		return -EINVAL;
+	}
+
+	memset(buf, 0, PAGE_SIZE);
+	snprintf(buf, PAGE_SIZE, "%u", orig_floor_freq);
+
+	/* Restore the original value. */
+	ret = store_amd_pstate_floor_freq(policy, buf, strlen(buf));
+	if (ret < 0) {
+		pr_err("Failed to restore floor frequency to %s\n", buf);
+		return ret;
+	}
+
+	return 0;
+}
+
 static int __init amd_pstate_ut_init(void)
 {
 	u32 i = 0, arr_size = ARRAY_SIZE(amd_pstate_ut_cases);
@@ -578,10 +654,16 @@ static int __init amd_pstate_ut_init(void)
 
 		ret = amd_pstate_ut_cases[i].func(i);
 
-		if (ret)
+		if (ret) {
+			/* Platform does not support the feature being tested. */
+			if (ret == -EOPNOTSUPP) {
+				pr_err("%-4d %-20s\t skipped!\n", i+1, amd_pstate_ut_cases[i].name);
+				continue;
+			}
 			pr_err("%-4d %-20s\t fail: %d!\n", i+1, amd_pstate_ut_cases[i].name, ret);
-		else
+		} else {
 			pr_info("%-4d %-20s\t success!\n", i+1, amd_pstate_ut_cases[i].name);
+		}
 	}
 
 	return 0;
diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 93d275da12c6..ea6cc072121f 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -1505,8 +1505,7 @@ ssize_t show_energy_performance_preference(struct cpufreq_policy *policy, char *
 }
 EXPORT_SYMBOL_FOR_PSTATE_UT(show_energy_performance_preference);
 
-static ssize_t store_amd_pstate_floor_freq(struct cpufreq_policy *policy,
-					   const char *buf, size_t count)
+ssize_t store_amd_pstate_floor_freq(struct cpufreq_policy *policy, const char *buf, size_t count)
 {
 	struct amd_cpudata *cpudata = policy->driver_data;
 	union perf_cached perf = READ_ONCE(cpudata->perf);
@@ -1529,13 +1528,15 @@ static ssize_t store_amd_pstate_floor_freq(struct cpufreq_policy *policy,
 
 	return ret ?: count;
 }
+EXPORT_SYMBOL_FOR_PSTATE_UT(store_amd_pstate_floor_freq);
 
-static ssize_t show_amd_pstate_floor_freq(struct cpufreq_policy *policy, char *buf)
+ssize_t show_amd_pstate_floor_freq(struct cpufreq_policy *policy, char *buf)
 {
 	struct amd_cpudata *cpudata = policy->driver_data;
 
 	return sysfs_emit(buf, "%u\n", cpudata->floor_freq);
 }
+EXPORT_SYMBOL_FOR_PSTATE_UT(show_amd_pstate_floor_freq);
 
 static ssize_t show_amd_pstate_floor_count(struct cpufreq_policy *policy, char *buf)
 {
diff --git a/drivers/cpufreq/amd-pstate.h b/drivers/cpufreq/amd-pstate.h
index edd697a5e29f..f8e2f6ba1534 100644
--- a/drivers/cpufreq/amd-pstate.h
+++ b/drivers/cpufreq/amd-pstate.h
@@ -160,6 +160,8 @@ ssize_t store_energy_performance_preference(struct cpufreq_policy *policy,
 				    const char *buf, size_t count);
 ssize_t show_energy_performance_preference(struct cpufreq_policy *policy, char *buf);
 void amd_pstate_clear_dynamic_epp(struct cpufreq_policy *policy);
+ssize_t store_amd_pstate_floor_freq(struct cpufreq_policy *policy, const char *buf, size_t count);
+ssize_t show_amd_pstate_floor_freq(struct cpufreq_policy *policy, char *buf);
 
 struct freq_attr;
 
-- 
2.34.1