linux-kernel - [PATCH v4 1/4] selftests/resctrl: Generalize non-contiguous CAT check

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Message-Id: <20240903144528.46811-2-ilpo.jarvinen@linux.intel.com>
Date: Tue,  3 Sep 2024 17:45:25 +0300
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Muhammad Usama Anjum <usama.anjum@...labora.com>,
	Shuah Khan <shuah@...nel.org>,
	Reinette Chatre <reinette.chatre@...el.com>,
	linux-kselftest@...r.kernel.org,
	Fenghua Yu <fenghua.yu@...el.com>,
	linux-kernel@...r.kernel.org
Cc: Shaopeng Tan <tan.shaopeng@...fujitsu.com>,
	Maciej Wieczór-Retman <maciej.wieczor-retman@...el.com>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Subject: [PATCH v4 1/4] selftests/resctrl: Generalize non-contiguous CAT check

arch_supports_noncont_cat() checks if vendor is ARCH_AMD and if that is
not true, ARCH_INTEL is assumed which might not be true either because
get_vendor() can also return zero if neither AMD nor Intel is detected.

Generalize the vendor check using switch/case logic and return false
for unknown vendors.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Reviewed-by: Muhammad Usama Anjum <usama.anjum@...labora.com>
---
 tools/testing/selftests/resctrl/cat_test.c | 26 +++++++++++++---------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c
index 742782438ca3..51a1cb6aac34 100644
--- a/tools/testing/selftests/resctrl/cat_test.c
+++ b/tools/testing/selftests/resctrl/cat_test.c
@@ -292,19 +292,25 @@ 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)
+	switch (get_vendor()) {
+	case ARCH_AMD:
+		/* AMD always supports non-contiguous CBM. */
 		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;
+	case ARCH_INTEL:
+		/* 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);
 
-	return ((ecx >> 3) & 1);
+	default:
+		return false;
+	}
 }
 
 static int noncont_cat_run_test(const struct resctrl_test *test,
-- 
2.39.2