linux-kernel - [PATCH v2] selftests/resctrl: Fix noncont_cat_run

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Date: Mon, 10 Jun 2024 11:00:22 -0500
From: Babu Moger <babu.moger@....com>
To: <fenghua.yu@...el.com>, <reinette.chatre@...el.com>, <shuah@...nel.org>
CC: <linux-kernel@...r.kernel.org>, <linux-kselftest@...r.kernel.org>,
	<ilpo.jarvinen@...ux.intel.com>, <babu.moger@....com>,
	<maciej.wieczor-retman@...el.com>, <peternewman@...gle.com>,
	<eranian@...gle.com>
Subject: [PATCH v2] selftests/resctrl: Fix noncont_cat_run_test for AMD

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@....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