linux-kernel - Re: [PATCH 2/2] cpufreq/amd-pstate-ut: Don't fail boost test case if CPB isn't supported

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Message-ID: <87jzi2rgwj.fsf@BLR-5CG11610CF.amd.com>
Date: Wed, 3 Jul 2024 14:28:20 +0530
From: Gautham R.Shenoy <gautham.shenoy@....com>
To: Mario Limonciello <mario.limonciello@....com>
CC: Meng Li <li.meng@....com>, Perry Yuan <perry.yuan@....com>, "open list:AMD
 PSTATE DRIVER" <linux-pm@...r.kernel.org>, open list
	<linux-kernel@...r.kernel.org>, Dhananjay Ugwekar
	<Dhananjay.Ugwekar@....com>, Mario Limonciello <mario.limonciello@....com>
Subject: Re: [PATCH 2/2] cpufreq/amd-pstate-ut: Don't fail boost test case
 if CPB isn't supported

Hello Mario,

Mario Limonciello <mario.limonciello@....com> writes:

> cpudata->boost_supported will only be configured when a CPU actually
> supports core performance boost. Add an extra guard into the check
> to ensure it only runs when CPB is present.
>
> Fixes: 14eb1c96e3a3 ("cpufreq: amd-pstate: Add test module for amd-pstate driver")
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> ---
>  drivers/cpufreq/amd-pstate-ut.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate-ut.c b/drivers/cpufreq/amd-pstate-ut.c
> index b7318669485e..b011c729fcba 100644
> --- a/drivers/cpufreq/amd-pstate-ut.c
> +++ b/drivers/cpufreq/amd-pstate-ut.c
> @@ -232,21 +232,21 @@ static void amd_pstate_ut_check_freq(u32 index)
>  			goto skip_test;
>  		}
>  
> -		if (cpudata->boost_supported) {
> -			if ((policy->max == cpudata->max_freq) ||
> -					(policy->max == nominal_freq_khz))
> -				amd_pstate_ut_cases[index].result = AMD_PSTATE_UT_RESULT_PASS;
> -			else {
> +		if (cpu_feature_enabled(X86_FEATURE_CPB)) {
> +			if (!cpudata->boost_supported) {
> +				amd_pstate_ut_cases[index].result = AMD_PSTATE_UT_RESULT_FAIL;
> +				pr_err("%s cpu%d must support boost!\n", __func__, cpu);
> +				goto skip_test;
> +			}
> +			if ((policy->max != cpudata->max_freq) &&
> +			    (policy->max != nominal_freq_khz)) {

Writing a different value into
/sys/devices/system/cpu/cpuX/cpufreq/scaling_max_freq, updates the
policy->max for cpuX.

So if a user runs this test case after someone has changed the
scaling_max_freq, the test case will fail. While this is not due to your
patch, I wonder if this is valid test-case.

>  				amd_pstate_ut_cases[index].result = AMD_PSTATE_UT_RESULT_FAIL;
>  				pr_err("%s cpu%d policy_max=%d should be equal cpu_max=%d or cpu_nominal=%d !\n",
>  					__func__, cpu, policy->max, cpudata->max_freq,
>  					nominal_freq_khz);
>  				goto skip_test;
>  			}
> -		} else {
> -			amd_pstate_ut_cases[index].result = AMD_PSTATE_UT_RESULT_FAIL;
> -			pr_err("%s cpu%d must support boost!\n", __func__, cpu);
> -			goto skip_test;
> +			amd_pstate_ut_cases[index].result = AMD_PSTATE_UT_RESULT_PASS;
>  		}
>  		cpufreq_cpu_put(policy);
>  	}
> -- 
> 2.43.0
--
Thanks and Regards
gautham.