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

[Andrea Cervesato]

Hi!

> Verify for all online logical CPUs that their highest performance value are
> the same for HWP Capability MSR 0x771 and CPPC sysfs file.
> ---
>  testcases/kernel/power_management/.gitignore  |  1 +
>  .../power_management/high_freq_hwp_cap_cppc.c | 57 +++++++++++++++++++
>  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/
> + */

Remove space
> +
> +/*\
> + * Verify for all online logical CPUs  that their highest performance value are

Double space before "that"

> + * 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);

snprintf(path, sizeof(path), ..) is better.

> +		SAFE_FILE_SCANF(path, "%llu", &sysfs_highest_perf);
> +		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");
> +		}

Simply use SAFE_PREAD(). fd will be closed when test ends.

> +		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);

Why tst_brk() ? It's supposed to be tst_res(TFAIL, ..).

> +	}
> +
> +	tst_res(TPASS, "Test pass");
> +}
> +
> +static struct tst_test test = {
> +	.needs_kconfigs = (const char *const []) {
> +		"CONFIG_X86_MSR",

The CPPC sysfs interface also requires CONFIG_ACPI_CPPC_LIB to be built.

> +		NULL
> +	},
> +	.needs_root = 1,
> +	.setup = setup,
> +	.test_all = run
> +};
> -- 
> 2.47.3
> 
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There's also no runtest entry for this test, so it can't be run in the testing
suites by kirk.

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