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

[Petr Vorel]

Hi Piotr,

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

You were supposed to add your RBT:
Signed-off-by: Piotr Kubaj <piotr.kubaj@intel.com>

> ---
>  testcases/kernel/power_management/.gitignore  |  1 +
>  .../power_management/high_freq_hwp_cap_cppc.c | 57 +++++++++++++++++++

You did not add test into runtest/thermal. OTOH test will apply also after we
finally merge thermal_interrupt_events.c.

>  2 files changed, 58 insertions(+)
>  create mode 100644 testcases/kernel/power_management/high_freq_hwp_cap_cppc.c

> 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..4cbb81f0b
> --- /dev/null
> +++ b/testcases/kernel/power_management/high_freq_hwp_cap_cppc.c
> @@ -0,0 +1,57 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +
> +/*
> + * Copyright (C) 2025-2026 Intel - http://www.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"
> +
> +static int nproc;
> +
> +static void setup(void)
> +{
> +	nproc = tst_ncpus();
> +}
> +
> +static void run(void)
> +{
> +	for (int i = 0; i < nproc; i++) {
> +		char path[PATH_MAX];
> +		unsigned long long msr_highest_perf = 0, sysfs_highest_perf = 0;
> +
> +		snprintf(path, PATH_MAX, "/sys/devices/system/cpu/cpu%d/acpi_cppc/highest_perf", i);
> +		SAFE_FILE_SCANF(path, "%llu", &sysfs_highest_perf);

I tried to run the test, but it fails due missing sysfs file:

$ grep CONFIG_X86_MSR /boot/config-6.19.0-rc1-1.g274aff5-default 
CONFIG_X86_MSR=m

$ lsmod |grep msr
intel_rapl_msr         20480  0
intel_rapl_common      53248  1 intel_rapl_msr

# ./high_freq_hwp_cap_cppc 
tst_test.c:1887: TINFO: Overall timeout per run is 0h 02m 00s
...
high_freq_hwp_cap_cppc.c:28: TBROK: Failed to open FILE '/sys/devices/system/cpu/cpu0/acpi_cppc/highest_perf' for reading: ENOENT (2)

# modprobe msr

$ lsmod |grep msr
msr                    12288  0
intel_rapl_msr         20480  0
intel_rapl_common      53248  1 intel_rapl_msr

# ./high_freq_hwp_cap_cppc
...
high_freq_hwp_cap_cppc.c:28: TBROK: Failed to open FILE '/sys/devices/system/cpu/cpu0/acpi_cppc/highest_perf' for reading: ENOENT (2)

=> obviously checking for CONFIG_X86_MSR is not enough.

OT: it'd be nice to extend 'save_restore' library functionality to
1) support glob (/sys/devices/system/cpu/cpu*/acpi_cppc/highest_perf)
2) read value into the variable (in case of glob into array).

> +		tst_res(TDEBUG, "%s: %llu", path, sysfs_highest_perf);
> +
> +		snprintf(path, PATH_MAX, "/dev/cpu/%d/msr", i);
> +		int fd = SAFE_OPEN(path, O_RDONLY);
> +
> +		if (pread(fd, &msr_highest_perf, sizeof(msr_highest_perf), 0x771) < 0) {
> +			SAFE_CLOSE(fd);
> +			tst_brk(TBROK | TERRNO, "MSR read error");
> +		}
> +		SAFE_CLOSE(fd);
> +		msr_highest_perf &= (1ULL << 8) - 1;
> +		tst_res(TDEBUG, "%s: %llu", path, msr_highest_perf);
> +
> +		if (msr_highest_perf != sysfs_highest_perf)
> +			tst_brk(TFAIL, "CPU %d: highest performance values differ between sysfs and MSR", i);
> +	}
> +
> +	tst_res(TPASS, "Test pass");

"Test pass" has zero information value.
Maybe something like:
"sysfs and MSR values are equal"

> +}
> +
> +static struct tst_test test = {
> +	.needs_kconfigs = (const char *const []) {
> +		"CONFIG_X86_MSR",
> +		NULL
> +	},
For thermal_interrupt_events.c we also have use .supported_archs (for the docs
purposes), why not to add it to this test as well?

+	.supported_archs = (const char *const []) {
+		"x86",
+		"x86_64",
+		NULL
+	},

Kind regards,
Petr

> +	.needs_root = 1,
> +	.setup = setup,
> +	.test_all = run
> +};