A CAT allocation is a CBM, and the kernel must refuse masks that can't describe a valid allocation. Nothing in the suite check this.
Implement L3_CAT_VALIDATE, first confirm a valid full mask is accepted, then write an empty mask and a mask with bits outside cbm_mask and confirm each is refused. A mask below min_cbm_bits is also checked where the platform needs more than one bit. Signed-off-by: Richard Cheng <[email protected]> --- tools/testing/selftests/resctrl/cat_test.c | 79 +++++++++++++++++++ tools/testing/selftests/resctrl/resctrl.h | 1 + .../testing/selftests/resctrl/resctrl_tests.c | 1 + 3 files changed, 81 insertions(+) diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c index 16a947f1ed16..d236988916d9 100644 --- a/tools/testing/selftests/resctrl/cat_test.c +++ b/tools/testing/selftests/resctrl/cat_test.c @@ -603,3 +603,82 @@ struct resctrl_test l3_cat_occup_test = { .run_test = cat_occup_run_test, .cleanup = cat_occup_test_cleanup, }; + +/* + * L3_CAT_VALIDATE - Verify the kernel rejects invalid L3 CBM writes. + * + * CAT allocation accepts a Capacity Bit Mask (CBM). The kernel must reject + * masks that cannot represent a valid allocation: an empty mask, a mask with + * bits outside cbm_mask, or (where the platform requires it) a mask with + * fewer than min_cbm_bits bits. A rejected schemata write makes + * write_schemata() return non-zero, which is the signal this test checks. + */ +static int cat_validate_run_test(const struct resctrl_test *test, + const struct user_params *uparams) +{ + unsigned long full_mask, bad_mask; + unsigned int min_cbm_bits, start; + char schemata[64]; + int count_of_bits, 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 1; + } + + /* An empty mask must be rejected. */ + if (!write_schemata("", "0", uparams->cpu, test->resource)) { + ksft_print_msg("Empty CBM was accepted, must be rejected\n"); + return 1; + } + + /* A mask with a bit outside cbm_mask must be rejected. */ + bad_mask = full_mask | (1UL << count_of_bits); + snprintf(schemata, sizeof(schemata), "%lx", bad_mask); + if (!write_schemata("", schemata, uparams->cpu, test->resource)) { + ksft_print_msg("Out-of-range CBM 0x%lx was accepted, must be rejected\n", + bad_mask); + return 1; + } + + /* + * A mask with fewer than min_cbm_bits bits must be rejected. When + * min_cbm_bits is 1 the only sub-minimum mask is the empty mask + * This case only applies when the platform requires more contiguous bits. + */ + if (min_cbm_bits > 1) { + count_contiguous_bits(full_mask, &start); + bad_mask = create_bit_mask(start, min_cbm_bits - 1); + snprintf(schemata, sizeof(schemata), "%lx", bad_mask); + if (!write_schemata("", schemata, uparams->cpu, test->resource)) { + ksft_print_msg("CBM 0x%lx with too few bits was accepted\n", + bad_mask); + return 1; + } + } + + ksft_print_msg("Pass: CAT rejects invalid CBM writes\n"); + + return 0; +} + +struct resctrl_test l3_cat_validate_test = { + .name = "L3_CAT_VALIDATE", + .group = "CAT", + .resource = "L3", + .feature_check = test_resource_feature_check, + .run_test = cat_validate_run_test, +}; diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h index ce3abf0bdac2..e2e3cf7833bc 100644 --- a/tools/testing/selftests/resctrl/resctrl.h +++ b/tools/testing/selftests/resctrl/resctrl.h @@ -248,6 +248,7 @@ extern struct resctrl_test mba_test; extern struct resctrl_test cmt_test; extern struct resctrl_test l3_cat_test; extern struct resctrl_test l3_cat_occup_test; +extern struct resctrl_test l3_cat_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 324a60818aa1..66739e96f33c 100644 --- a/tools/testing/selftests/resctrl/resctrl_tests.c +++ b/tools/testing/selftests/resctrl/resctrl_tests.c @@ -20,6 +20,7 @@ static struct resctrl_test *resctrl_tests[] = { &cmt_test, &l3_cat_test, &l3_cat_occup_test, + &l3_cat_validate_test, &l3_noncont_cat_test, &l2_noncont_cat_test, }; -- 2.43.0
