[LTP] [PATCH v7] high_freq_hwp_cap_cppc.c: new test

[LTP] [PATCH v7] high_freq_hwp_cap_cppc.c: new test

[Piotr Kubaj]

Verify for all online logical CPUs that their highest performance value are
the same for HWP Capability MSR 0x771 and CPPC sysfs file.

Signed-off-by: Piotr Kubaj <piotr.kubaj@intel.com>
---
Addresses Andrea's feedback.
 runtest/power_management_tests                |  1 +
 testcases/kernel/power_management/.gitignore  |  1 +
 .../power_management/high_freq_hwp_cap_cppc.c | 90 +++++++++++++++++++
 3 files changed, 92 insertions(+)
 create mode 100644 testcases/kernel/power_management/high_freq_hwp_cap_cppc.c

diff --git a/runtest/power_management_tests b/runtest/power_management_tests
index 884e615cd..6d87dfb7f 100644
--- a/runtest/power_management_tests
+++ b/runtest/power_management_tests
@@ -1,4 +1,5 @@
 #POWER_MANAGEMENT
+high_freq_hwp_cap_cppc high_freq_hwp_cap_cppc
 runpwtests01 runpwtests01.sh
 runpwtests02 runpwtests02.sh
 runpwtests03 runpwtests03.sh
diff --git a/testcases/kernel/power_management/.gitignore b/testcases/kernel/power_management/.gitignore
index 0c2a3ed4b..c13bca1c4 100644
--- a/testcases/kernel/power_management/.gitignore
+++ b/testcases/kernel/power_management/.gitignore
@@ -1 +1,2 @@
+high_freq_hwp_cap_cppc
 pm_get_sched_values
diff --git a/testcases/kernel/power_management/high_freq_hwp_cap_cppc.c b/testcases/kernel/power_management/high_freq_hwp_cap_cppc.c
new file mode 100644
index 000000000..3cd7db221
--- /dev/null
+++ b/testcases/kernel/power_management/high_freq_hwp_cap_cppc.c
@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2026 Piotr Kubaj <piotr.kubaj@intel.com>
+ */
+
+/*\
+ * Verify for all online logical CPUs that their highest performance value are
+ * the same for HWP Capability MSR 0x771 and CPPC sysfs file.
+ */
+
+#include "tst_test.h"
+#include "tst_safe_prw.h"
+
+#define MSR_HWP_CAPABILITIES	0x771
+#define HIGHEST_PERF_MASK	0xFF
+
+static int nproc;
+
+static void setup(void)
+{
+	nproc = tst_ncpus_conf();
+}
+
+static void run(void)
+{
+	bool status = true;
+
+	for (int i = 0; i < nproc; i++) {
+		int online = 1;
+		char path[PATH_MAX];
+		unsigned long long msr_highest_perf = 0, sysfs_highest_perf = 0;
+
+		snprintf(path, sizeof(path), "/sys/devices/system/cpu/cpu%d/online", i);
+		if (i)
+			SAFE_FILE_SCANF(path, "%d", &online);
+
+		if (!online) {
+			tst_res(TINFO, "CPU%d offline, skipping", i);
+			continue;
+		}
+
+		snprintf(path, sizeof(path), "/sys/devices/system/cpu/cpu%d/acpi_cppc/highest_perf", i);
+		if (access(path, F_OK) == -1) {
+			tst_res(TCONF | TERRNO, "CPPC sysfs not available, skipping");
+			return;
+		}
+
+		SAFE_FILE_SCANF(path, "%llu", &sysfs_highest_perf);
+		tst_res(TDEBUG, "%s: %llu", path, sysfs_highest_perf);
+
+		snprintf(path, sizeof(path), "/dev/cpu/%d/msr", i);
+		int fd = SAFE_OPEN(path, O_RDONLY);
+
+		SAFE_PREAD(1, fd, &msr_highest_perf, sizeof(msr_highest_perf), MSR_HWP_CAPABILITIES);
+		SAFE_CLOSE(fd);
+		msr_highest_perf &= HIGHEST_PERF_MASK;
+		tst_res(TDEBUG, "%s: %llu", path, msr_highest_perf);
+
+		if (msr_highest_perf != sysfs_highest_perf) {
+			tst_res(TINFO, "cpu%d: sysfs=%llu MSR=%llu",
+				i, sysfs_highest_perf, msr_highest_perf);
+			status = false;
+		}
+	}
+
+	if (status)
+		tst_res(TPASS, "Sysfs and MSR values are equal");
+	else
+		tst_res(TFAIL, "Highest performance values differ between sysfs and MSR");
+}
+
+static struct tst_test test = {
+	.needs_drivers = (const char *const []) {
+		"msr",
+		NULL
+	},
+	.needs_kconfigs = (const char *const []) {
+		"CONFIG_ACPI_CPPC_LIB",
+		"CONFIG_X86_MSR",
+		NULL
+	},
+	.needs_root = 1,
+	.setup = setup,
+	.supported_archs = (const char *const []) {
+		"x86",
+		"x86_64",
+		NULL
+	},
+	.test_all = run
+};
-- 
2.47.3

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Re: [LTP] high_freq_hwp_cap_cppc.c: new test

[linuxtestproject.agent]

Hi Piotr,

On Mon, 20 Apr 2026, Piotr Kubaj wrote:
> high_freq_hwp_cap_cppc.c: new test

Reviewed-by: LTP AI Reviewer <ltp-ai@noreply.github.com>

---
Note:

Our agent completed the review of the patch.

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Re: [LTP] [PATCH v7] high_freq_hwp_cap_cppc.c: new test

[Andrea Cervesato via ltp]

Hi Piotr,

I commented the wrong patch. Was v6, sorry. Let me complete the review
here.

> +static void run(void)
> +{
> +	bool status = true;
> +
> +	for (int i = 0; i < nproc; i++) {
> +		int online = 1;
> +		char path[PATH_MAX];

This can stay out of the loop. `snprintf()` adds a string terminator
so there's no issue with this.

> +		unsigned long long msr_highest_perf = 0, sysfs_highest_perf = 0;
> +
> +		snprintf(path, sizeof(path), "/sys/devices/system/cpu/cpu%d/online", i);
> +		if (i)

I think I missed a part here. Did you double check if `i == 0` creates
an issue while using SAFE_FILE_SCANF ? Please verify and eventually
remove this check.

> +			SAFE_FILE_SCANF(path, "%d", &online);

Regards,
--
Andrea Cervesato
SUSE QE Automation Engineer Linux
andrea.cervesato@suse.com

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Re: [LTP] [PATCH v7] high_freq_hwp_cap_cppc.c: new test

[Kubaj, Piotr]

2026-04-29 (水) の 07:53 +0000 に Andrea Cervesato さんは書きました:
> Hi Piotr,
> 
> I commented the wrong patch. Was v6, sorry. Let me complete the
> review
> here.
> 
> > +static void run(void)
> > +{
> > +	bool status = true;
> > +
> > +	for (int i = 0; i < nproc; i++) {
> > +		int online = 1;
> > +		char path[PATH_MAX];
> 
> This can stay out of the loop. `snprintf()` adds a string terminator
> so there's no issue with this.
Fixed.

> 
> > +		unsigned long long msr_highest_perf = 0,
> > sysfs_highest_perf = 0;
> > +
> > +		snprintf(path, sizeof(path),
> > "/sys/devices/system/cpu/cpu%d/online", i);
> > +		if (i)
> 
> I think I missed a part here. Did you double check if `i == 0`
> creates
> an issue while using SAFE_FILE_SCANF ? Please verify and eventually
> remove this check.
Yes, it's necessary. "online" is not available for cpu0, I think it's
assumed to be always online.

> 
> > +			SAFE_FILE_SCANF(path, "%d", &online);
> 
> Regards,
> --
> Andrea Cervesato
> SUSE QE Automation Engineer Linux
> andrea.cervesato@suse.com
---------------------------------------------------------------------
Intel Technology Poland sp. z o.o.
ul. Slowackiego 173 | 80-298 Gdansk | Sad Rejonowy Gdansk Polnoc | VII Wydzial Gospodarczy Krajowego Rejestru Sadowego - KRS 101882 | NIP 957-07-52-316 | Kapital zakladowy 200.000 PLN.
Spolka oswiadcza, ze posiada status duzego przedsiebiorcy w rozumieniu ustawy z dnia 8 marca 2013 r. o przeciwdzialaniu nadmiernym opoznieniom w transakcjach handlowych.

Ta wiadomosc wraz z zalacznikami jest przeznaczona dla okreslonego adresata i moze zawierac informacje poufne. W razie przypadkowego otrzymania tej wiadomosci, prosimy o powiadomienie nadawcy oraz trwale jej usuniecie; jakiekolwiek przegladanie lub rozpowszechnianie jest zabronione.
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Re: [LTP] high_freq_hwp_cap_cppc.c: new test

[linuxtestproject.agent]

Hi Piotr,

On Mon, 4 May 2026 12:17:36 +0200, Piotr Kubaj wrote:
> high_freq_hwp_cap_cppc.c: new test
>
> Verify for all online logical CPUs that their highest performance value are
> the same for HWP Capability MSR 0x771 and CPPC sysfs file.

The body describes what the test does but not why it is needed. Please
add at least one sentence explaining the motivation — e.g. a known
inconsistency, a kernel regression, or a new interface being validated.

[...]

> +		snprintf(path, sizeof(path), "/dev/cpu/%d/msr", i);
> +		int fd = SAFE_OPEN(path, O_RDONLY);
> +
> +		SAFE_PREAD(1, fd, &msr_highest_perf, sizeof(msr_highest_perf), MSR_HWP_CAPABILITIES);
> +		SAFE_CLOSE(fd);

If SAFE_PREAD aborts via tst_brk(), cleanup() is called but fd is never
closed because it is a loop-local variable with no cleanup handler.
Promote fd to a static (initialized to -1) and add a cleanup() that
guards with `if (fd != -1) SAFE_CLOSE(fd);`.

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Re: [LTP] high_freq_hwp_cap_cppc.c: new test

[linuxtestproject.agent]

Hi Piotr,

On Tue, 5 May 2026, Piotr Kubaj wrote:
> high_freq_hwp_cap_cppc.c: new test

Reviewed-by: LTP AI Reviewer <ltp-ai@noreply.github.com>

---
Note:

Our agent completed the review of the patch.

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findings are genuine. If you find issues with the review, please
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Re: [LTP] high_freq_hwp_cap_cppc.c: new test

[linuxtestproject.agent]

Hi Piotr,

On Wed, 6 May 2026 14:56:51 +0200, Piotr Kubaj wrote:
> [PATCH] high_freq_hwp_cap_cppc.c: new test

> +static int *mismatch;
[...]
> +		if (msr_highest_perf != sysfs_highest_perf) {
> +			tst_res(TINFO, "cpu%d: sysfs=%llu MSR=%llu",
> +				i, sysfs_highest_perf, msr_highest_perf);
> +			mismatch[i] = 1;

`mismatch[]` is zeroed by SAFE_CALLOC in setup() but never cleared at the
start of run(). With -i N, stale flags from a prior iteration persist and
the per-CPU summary falsely reports "MISMATCH" for CPUs that are now
matching. Add:

    memset(mismatch, 0, nproc * sizeof(*mismatch));

at the top of run().

---
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Re: [LTP] high_freq_hwp_cap_cppc.c: new test

[linuxtestproject.agent]

Hi Piotr,

On 2026-05-07, Piotr Kubaj wrote:
> high_freq_hwp_cap_cppc.c: new test

> +	mismatch = SAFE_MALLOC(nproc, sizeof(int));

SAFE_MALLOC takes a single size argument. This will not compile.
Use SAFE_CALLOC(nproc, sizeof(int)) instead.

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Re: [LTP] high_freq_hwp_cap_cppc.c: new test

[linuxtestproject.agent]

Hi Piotr,

On Thu, 14 May 2026, Piotr Kubaj wrote:
> high_freq_hwp_cap_cppc.c: new test

Reviewed-by: LTP AI Reviewer <ltp-ai@noreply.github.com>

---
Note:

Our agent completed the review of the patch.

The agent can sometimes produce false positives although often its
findings are genuine. If you find issues with the review, please
comment this email or ignore the suggestions.

Regards,
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