Hi Richard,
On 8/10/26 2:51 AM, Richard Cheng wrote:
> Add L3_CBM_VALIDATE to verify that resctrl enforces the L3 CBM rules
> advertised by cbm_mask and min_cbm_bits.
>
> Confirm that the full mask is accepted. Check the empty mask according
> to min_cbm_bits, and confirm that out-of-range and undersized masks are
> rejected.
>
> This catches inconsistencies between the advertised capabilities and
> schemata validation.
>
> Signed-off-by: Richard Cheng <[email protected]>
> ---
....
> diff --git a/tools/testing/selftests/resctrl/cat_test.c
> b/tools/testing/selftests/resctrl/cat_test.c
> index 371a2f26dc47..a06c57954740 100644
> --- a/tools/testing/selftests/resctrl/cat_test.c
> +++ b/tools/testing/selftests/resctrl/cat_test.c
> @@ -357,6 +357,89 @@ static bool noncont_cat_feature_check(const struct
> resctrl_test *test)
> return resource_info_file_exists(test->resource, "sparse_masks");
> }
>
> +/*
> + * L3_CBM_VALIDATE - Verify L3 CBM write validation.
> + *
> + * A full CBM must be accepted. An empty CBM is valid only when min_cbm_bits
> + * is zero. Masks with bits outside cbm_mask or fewer than min_cbm_bits must
> + * be rejected.
> + */
> +static int cbm_validate_run_test(const struct resctrl_test *test,
> + const struct user_params *uparams)
Nothing about this function (except the hardcoded string in the final "Pass:"
message) is specific to L3. It looks to me as though an L2 variant of this test
can
easily be added with just a new "struct resctrl_test l2_cbm_validate_test"?
(more below)
The "Pass:" message can just use resctrl_test::resource instead of the
hardcoded "L3".
> +{
> + unsigned int min_cbm_bits, contiguous_bits;
> + unsigned long long invalid_mask;
> + unsigned int count_of_bits;
> + unsigned long full_mask;
> + unsigned int start;
> + char schemata[64];
> + int ret;
> +
> + ret = get_full_cbm(test->resource, &full_mask);
> + if (ret)
> + return ret;
> +
> + ret = resource_info_unsigned_get(test->resource, "min_cbm_bits",
> + &min_cbm_bits);
> + if (ret)
> + return ret;
> +
> + count_of_bits = count_bits(full_mask);
> +
> + /* A valid full CBM must be accepted. */
> + snprintf(schemata, sizeof(schemata), "%lx", full_mask);
> + if (write_schemata("", schemata, uparams->cpu, test->resource)) {
> + ksft_print_msg("Valid CBM 0x%lx was rejected\n", full_mask);
> + return KSFT_FAIL;
> + }
> +
> + ret = write_schemata("", "0", uparams->cpu, test->resource);
> + if (min_cbm_bits && !ret) {
> + ksft_print_msg("Empty CBM was accepted, must be rejected\n");
> + return KSFT_FAIL;
> + }
> + if (!min_cbm_bits && ret) {
> + ksft_print_msg("Empty CBM was rejected, must be accepted\n");
> + return KSFT_FAIL;
> + }
> +
> + /* A mask with a bit outside cbm_mask must be rejected. */
> + invalid_mask = (unsigned long long)full_mask | (1ULL << count_of_bits);
> + snprintf(schemata, sizeof(schemata), "%llx", invalid_mask);
> + if (!write_schemata("", schemata, uparams->cpu, test->resource)) {
> + ksft_print_msg("Out-of-range CBM 0x%llx was accepted, must be
> rejected\n",
> + invalid_mask);
> + return KSFT_FAIL;
> + }
> +
> + /*
> + * When min_cbm_bits is greater than one, a non-empty mask with fewer
> + * bits must be rejected.
> + */
> + if (min_cbm_bits > 1) {
> + contiguous_bits = count_contiguous_bits(full_mask, &start);
> + if (contiguous_bits < min_cbm_bits) {
> + ksft_print_msg("Full CBM has %u contiguous bits, fewer
> than "
> + "min_cbm_bits=%u\n",
Please do not split this message across two lines. If you want to appease
checkpatch.pl you
can merge the two lines and drop "fewer than". For example,
ksft_print_msg("Full CBM has %u contiguous bits,
min_cbm_bits=%u\n",
Just merging them as-is is fine also. You will find this file to have messages
with even
longer lines (see noncont_cat_run_test()).
> + contiguous_bits, min_cbm_bits);
> + return KSFT_FAIL;
> + }
> +
> + invalid_mask = create_bit_mask(start, min_cbm_bits - 1);
> + snprintf(schemata, sizeof(schemata), "%llx", invalid_mask);
> + if (!write_schemata("", schemata, uparams->cpu,
> + test->resource)) {
> + ksft_print_msg("CBM 0x%llx with too few bits was
> accepted\n",
> + invalid_mask);
> + return KSFT_FAIL;
> + }
> + }
> +
> + ksft_print_msg("Pass: L3 CBM writes were validated correctly\n");
> +
> + return 0;
> +}
> +
> struct resctrl_test l3_cat_test = {
> .name = "L3_CAT",
> .group = "CAT",
> @@ -366,6 +449,14 @@ struct resctrl_test l3_cat_test = {
> .cleanup = cat_test_cleanup,
> };
>
> +struct resctrl_test l3_cbm_validate_test = {
> + .name = "L3_CBM_VALIDATE",
> + .group = "CAT",
> + .resource = "L3",
> + .feature_check = test_resource_feature_check,
> + .run_test = cbm_validate_run_test,
> +};
As hinted earlier, something like below (with supporting changes in resctrl.h
and resctrl_tests.c)
should be all that is needed to expand coverage to L2:
struct resctrl_test l2_cbm_validate_test = {
.name = "L2_CBM_VALIDATE",
.group = "CAT",
.resource = "L2",
.feature_check = test_resource_feature_check,
.run_test = cbm_validate_run_test,
};
> +
> struct resctrl_test l3_noncont_cat_test = {
> .name = "L3_NONCONT_CAT",
> .group = "CAT",
> diff --git a/tools/testing/selftests/resctrl/resctrl.h
> b/tools/testing/selftests/resctrl/resctrl.h
> index 175101022bf3..a6fc688ed997 100644
> --- a/tools/testing/selftests/resctrl/resctrl.h
> +++ b/tools/testing/selftests/resctrl/resctrl.h
> @@ -240,6 +240,7 @@ extern struct resctrl_test mbm_test;
> extern struct resctrl_test mba_test;
> extern struct resctrl_test cmt_test;
> extern struct resctrl_test l3_cat_test;
> +extern struct resctrl_test l3_cbm_validate_test;
> extern struct resctrl_test l3_noncont_cat_test;
> extern struct resctrl_test l2_noncont_cat_test;
>
> diff --git a/tools/testing/selftests/resctrl/resctrl_tests.c
> b/tools/testing/selftests/resctrl/resctrl_tests.c
> index dbcd5eea9fbc..57a4d0815b67 100644
> --- a/tools/testing/selftests/resctrl/resctrl_tests.c
> +++ b/tools/testing/selftests/resctrl/resctrl_tests.c
> @@ -19,6 +19,7 @@ static struct resctrl_test *resctrl_tests[] = {
> &mba_test,
> &cmt_test,
> &l3_cat_test,
> + &l3_cbm_validate_test,
> &l3_noncont_cat_test,
> &l2_noncont_cat_test,
> };
Reinette
