[PATCH v2] selftests/resctrl: Fix noncont_cat_run_test for AMD

Babu Moger
2024-06-10T16:00:42Z

The selftest noncont_cat_run_test fails on AMD with the warnings. Reason
is, AMD supports non contiguous CBM masks but does not report it via CPUID.

Update noncont_cat_run_test to check for the vendor when verifying CPUID.

Fixes: ae638551ab64 ("selftests/resctrl: Add non-contiguous CBMs CAT test")
Signed-off-by: Babu Moger <babu.moger@amd.com>
---
v2: Moved the non contiguous 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;
}

--
2.34.1