linux-kernel - Re: [PATCH 1/3] selftests/resctrl: Generalize non-contiguous CAT check

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Message-ID: <b24092fa-ed99-4373-a23f-a890969adcd8@collabora.com>
Date: Thu, 22 Aug 2024 09:48:47 +0500
From: Muhammad Usama Anjum <Usama.Anjum@...labora.com>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
 Shuah Khan <shuah@...nel.org>, Reinette Chatre <reinette.chatre@...el.com>,
 linux-kselftest@...r.kernel.org
Cc: Usama.Anjum@...labora.com, linux-kernel@...r.kernel.org,
 Shaopeng Tan <tan.shaopeng@...fujitsu.com>, Fenghua Yu <fenghua.yu@...el.com>
Subject: Re: [PATCH 1/3] selftests/resctrl: Generalize non-contiguous CAT
 check

On 8/13/24 3:45 PM, Ilpo Järvinen wrote:
> arch_supports_noncont_cat() checks if vendor is ARCH_AMD and if that is
> not true, ARCH_INTEL is assumed which might not be true either because
> get_vendor() can also return zero if neither AMD nor Intel is detected.
> 
> Generalize the vendor check using switch/case logic and return false
> for unknown vendors.
> 
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Reviewed-by: Muhammad Usama Anjum <usama.anjum@...labora.com>

> ---
>  tools/testing/selftests/resctrl/cat_test.c | 26 +++++++++++++---------
>  1 file changed, 16 insertions(+), 10 deletions(-)
> 
> diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c
> index 742782438ca3..51a1cb6aac34 100644
> --- a/tools/testing/selftests/resctrl/cat_test.c
> +++ b/tools/testing/selftests/resctrl/cat_test.c
> @@ -292,19 +292,25 @@ static bool arch_supports_noncont_cat(const struct resctrl_test *test)
>  {
>  	unsigned int eax, ebx, ecx, edx;
>  
> -	/* AMD always supports non-contiguous CBM. */
> -	if (get_vendor() == ARCH_AMD)
> +	switch (get_vendor()) {
> +	case ARCH_AMD:
> +		/* AMD always supports non-contiguous CBM. */
>  		return true;
>  
> -	/* Intel support for non-contiguous CBM needs to be discovered. */
> -	if (!strcmp(test->resource, "L3"))
> -		__cpuid_count(0x10, 1, eax, ebx, ecx, edx);
> -	else if (!strcmp(test->resource, "L2"))
> -		__cpuid_count(0x10, 2, eax, ebx, ecx, edx);
> -	else
> -		return false;
> +	case ARCH_INTEL:
> +		/* Intel support for non-contiguous CBM needs to be discovered. */
> +		if (!strcmp(test->resource, "L3"))
> +			__cpuid_count(0x10, 1, eax, ebx, ecx, edx);
> +		else if (!strcmp(test->resource, "L2"))
> +			__cpuid_count(0x10, 2, eax, ebx, ecx, edx);
> +		else
> +			return false;
> +
> +		return ((ecx >> 3) & 1);
>  
> -	return ((ecx >> 3) & 1);
> +	default:
> +		return false;
> +	}
>  }
>  
>  static int noncont_cat_run_test(const struct resctrl_test *test,

-- 
BR,
Muhammad Usama Anjum