Re: [PATCH v3] selftests/resctrl: Fix non-contiguous CBM for AMD

Ilpo Järvinen
2024-06-12T07:33:39Z

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On Tue, 11 Jun 2024, Babu Moger wrote:

> The non-contiguous CBM test fails on AMD with:
> Starting L3_NONCONT_CAT test ...
> Mounting resctrl to "/sys/fs/resctrl"
> CPUID output doesn't match 'sparse_masks' file content!
> not ok 5 L3_NONCONT_CAT: test
>
> AMD always supports non-contiguous CBM but does not report it via CPUID.
>
> Fix the non-contiguous CBM test to use CPUID to discover non-contiguous
> CBM support only on Intel.
>
> Fixes: ae638551ab64 ("selftests/resctrl: Add non-contiguous CBMs CAT test")
> Signed-off-by: Babu Moger <babu.moger@amd.com>
> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>

Thanks.

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

--
i.

> ---
> v3: Reworked changelong.
>
> v2: Moved the non-contiguous CBM verification to a new function
> arch_supports_noncont_cat.
>
> v1: This was part of the series
> https://lore.kernel.org/lkml/cover.1708637563.git.babu.moger@amd.com/
> Sending this as a separate fix per review comments.
> ---
> tools/testing/selftests/resctrl/cat_test.c | 32 +++++++++++++++-------
> 1 file changed, 22 insertions(+), 10 deletions(-)
>
> diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c
> index d4dffc934bc3..742782438ca3 100644
> --- a/tools/testing/selftests/resctrl/cat_test.c
> +++ b/tools/testing/selftests/resctrl/cat_test.c
> @@ -288,11 +288,30 @@ static int cat_run_test(const struct resctrl_test *test, const struct user_param
> return ret;
> }
>
> +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)
> + 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;
> +
> + return ((ecx >> 3) & 1);
> +}
> +
> static int noncont_cat_run_test(const struct resctrl_test *test,
> const struct user_params *uparams)
> {
> unsigned long full_cache_mask, cont_mask, noncont_mask;
> - unsigned int eax, ebx, ecx, edx, sparse_masks;
> + unsigned int sparse_masks;
> int bit_center, ret;
> char schemata[64];
>
> @@ -301,15 +320,8 @@ static int noncont_cat_run_test(const struct resctrl_test *test,
> if (ret)
> return ret;
>
> - 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 -EINVAL;
> -
> - if (sparse_masks != ((ecx >> 3) & 1)) {
> - ksft_print_msg("CPUID output doesn't match 'sparse_masks' file content!\n");
> + if (arch_supports_noncont_cat(test) != sparse_masks) {
> + ksft_print_msg("Hardware and kernel differ on non-contiguous CBM support!\n");
> return 1;
> }
>
>