Re: [PATCH v4 5/5] selftests/resctrl: Add non-contiguous CBMs CAT test

On Mon, 5 Feb 2024, Maciej Wieczor-Retman wrote:

Add tests for both L2 and L3 CAT to verify the return values generated by writing non-contiguous CBMs don't contradict the reported non-contiguous support information.

Use a logical XOR to confirm return value of write_schemata() and non-contiguous CBMs support information match.

Signed-off-by: Maciej Wieczor-Retman maciej.wieczor-retman@intel.com

Changelog v4:

• Return failure instead of error on check of cpuid against sparse_masks and on contiguous write_schemata fail. (Reinette)

Changelog v3:

• Roll back __cpuid_count part. (Reinette)
• Update function name to read sparse_masks file.
• Roll back get_cache_level() changes.
• Add ksft_print_msg() to contiguous schemata write error handling (Reinette).

Changelog v2:

• Redo the patch message. (Ilpo)
• Tidy up __cpuid_count calls. (Ilpo)
• Remove redundant AND in noncont_mask calculations (Ilpo)
• Fix bit_center offset.
• Add newline before function return. (Ilpo)
• Group non-contiguous tests with CAT tests. (Ilpo)
• Use a helper for reading sparse_masks file. (Ilpo)
• Make get_cache_level() available in other source files. (Ilpo)

tools/testing/selftests/resctrl/cat_test.c | 81 +++++++++++++++++++ tools/testing/selftests/resctrl/resctrl.h | 2 + .../testing/selftests/resctrl/resctrl_tests.c | 2 + 3 files changed, 85 insertions(+)

diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c index 39fc9303b8e8..20eb978e624b 100644 --- a/tools/testing/selftests/resctrl/cat_test.c +++ b/tools/testing/selftests/resctrl/cat_test.c @@ -294,6 +294,71 @@ static int cat_run_test(const struct resctrl_test *test, const struct user_param return ret; } +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, ret, sparse_masks;
• char schemata[64];
• int bit_center;
• /* Check to compare sparse_masks content to CPUID output. */
• ret = resource_info_unsigned_get(test->resource, "sparse_masks", &sparse_masks);
• 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");
  

• return 1;
  

• }
• /* Write checks initialization. */
• ret = get_full_cbm(test->resource, &full_cache_mask);
• if (ret < 0)

• return ret;
  

• bit_center = count_bits(full_cache_mask) / 2;
• cont_mask = full_cache_mask >> bit_center;
• /* Contiguous mask write check. */
• snprintf(schemata, sizeof(schemata), "%lx", cont_mask);
• ret = write_schemata("", schemata, uparams->cpu, test->resource);
• if (ret) {

• ksft_print_msg("Write of contiguous CBM failed\n");
  

• return 1;
  

• }
• /*

• * Non-contiguous mask write check. CBM has a 0xf hole approximately in the middle.
  

• * Output is compared with support information to catch any edge case errors.
  

• */
  

• noncont_mask = ~(0xf << (bit_center - 2)) & full_cache_mask;

To be on the safe side, I think the types could be made to match here with 0xfUL to avoid sizeof(int) vs sizeof(unsigned long) related bit drops in the & (although it feel somewhat theoretical given the bitmask sizes we are currently seeing).

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