Patch "selftests/resctrl: Fix non-contiguous CBM for AMD" has been added to the 6.9-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    selftests/resctrl: Fix non-contiguous CBM for AMD

to the 6.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     selftests-resctrl-fix-non-contiguous-cbm-for-amd.patch
and it can be found in the queue-6.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 52d1d4fa34e30d4ec27a5ae145858f1dab380300
Author: Babu Moger <babu.moger@xxxxxxx>
Date:   Tue Jun 11 17:18:30 2024 -0500

    selftests/resctrl: Fix non-contiguous CBM for AMD
    
    [ Upstream commit 48236960c06d32370bfa6f2cc408e786873262c8 ]
    
    The non-contiguous CBM test fails on AMD with:
    Starting L3_NONCONT_CAT test ...
    Mounting resctrl to "/sys/fs/resctrl"
    CPUID output doesn't match 'sparse_masks' file content!
    not ok 5 L3_NONCONT_CAT: test
    
    AMD always supports non-contiguous CBM but does not report it via CPUID.
    
    Fix the non-contiguous CBM test to use CPUID to discover non-contiguous
    CBM support only on Intel.
    
    Fixes: ae638551ab64 ("selftests/resctrl: Add non-contiguous CBMs CAT test")
    Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
    Reviewed-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
    Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
    Signed-off-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c
index 4cb991be8e31b..178a41d4bb1be 100644
--- a/tools/testing/selftests/resctrl/cat_test.c
+++ b/tools/testing/selftests/resctrl/cat_test.c
@@ -294,11 +294,30 @@ 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];
 
@@ -307,15 +326,8 @@ 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;
 	}