linux-kernel - [PATCH v3] selftests: x86: skip the tests if prerequisites aren't fulfilled

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Message-Id: <20240327111720.3509180-1-usama.anjum@collabora.com>
Date: Wed, 27 Mar 2024 16:17:17 +0500
From: Muhammad Usama Anjum <usama.anjum@...labora.com>
To: Shuah Khan <shuah@...nel.org>,
	Muhammad Usama Anjum <usama.anjum@...labora.com>,
	"Chang S. Bae" <chang.seok.bae@...el.com>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Binbin Wu <binbin.wu@...ux.intel.com>,
	angquan yu <angquan21@...il.com>,
	Ingo Molnar <mingo@...nel.org>
Cc: kernel@...labora.com,
	linux-kselftest@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v3] selftests: x86: skip the tests if prerequisites aren't fulfilled

Skip instead of failing when prerequisite conditions aren't fulfilled,
such as invalid xstate values etc. This patch would make the tests show
as skip when run by:
  make -C tools/testing/selftests/ TARGETS=x86 run_tests

  ...
  # timeout set to 45
  # selftests: x86: amx_64
  # # xstate cpuid: invalid tile data size/offset: 0/0
  ok 42 selftests: x86: amx_64 # SKIP
  # timeout set to 45
  # selftests: x86: lam_64
  # # Unsupported LAM feature!
  ok 43 selftests: x86: lam_64 # SKIP
  ...

In amx test, Move away from check_cpuid_xsave() and start using
arch_prctl() to find out if amx support is present or not. In the
kernels where amx isn't present, arch_prctl returns -EINVAL. Hence it is
backward compatible.

Reviewed-by: Chang S. Bae <chang.seok.bae@...el.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Reviewed-by: Binbin Wu <binbin.wu@...ux.intel.com>
Signed-off-by: Muhammad Usama Anjum <usama.anjum@...labora.com>
---
Changes since v2:
- Update the changelog

Changes since v1:
- Use arch_prctl to check if amx is supported
---
 tools/testing/selftests/x86/amx.c | 27 ++++++++++-----------------
 tools/testing/selftests/x86/lam.c |  2 +-
 2 files changed, 11 insertions(+), 18 deletions(-)

diff --git a/tools/testing/selftests/x86/amx.c b/tools/testing/selftests/x86/amx.c
index d884fd69dd510..95aad6d8849be 100644
--- a/tools/testing/selftests/x86/amx.c
+++ b/tools/testing/selftests/x86/amx.c
@@ -103,21 +103,6 @@ static void clearhandler(int sig)
 
 #define CPUID_LEAF1_ECX_XSAVE_MASK	(1 << 26)
 #define CPUID_LEAF1_ECX_OSXSAVE_MASK	(1 << 27)
-static inline void check_cpuid_xsave(void)
-{
-	uint32_t eax, ebx, ecx, edx;
-
-	/*
-	 * CPUID.1:ECX.XSAVE[bit 26] enumerates general
-	 * support for the XSAVE feature set, including
-	 * XGETBV.
-	 */
-	__cpuid_count(1, 0, eax, ebx, ecx, edx);
-	if (!(ecx & CPUID_LEAF1_ECX_XSAVE_MASK))
-		fatal_error("cpuid: no CPU xsave support");
-	if (!(ecx & CPUID_LEAF1_ECX_OSXSAVE_MASK))
-		fatal_error("cpuid: no OS xsave support");
-}
 
 static uint32_t xbuf_size;
 
@@ -350,6 +335,7 @@ enum expected_result { FAIL_EXPECTED, SUCCESS_EXPECTED };
 
 /* arch_prctl() and sigaltstack() test */
 
+#define ARCH_GET_XCOMP_SUPP	0x1021
 #define ARCH_GET_XCOMP_PERM	0x1022
 #define ARCH_REQ_XCOMP_PERM	0x1023
 
@@ -928,8 +914,15 @@ static void test_ptrace(void)
 
 int main(void)
 {
-	/* Check hardware availability at first */
-	check_cpuid_xsave();
+	unsigned long features;
+	long rc;
+
+	rc = syscall(SYS_arch_prctl, ARCH_GET_XCOMP_SUPP, &features);
+	if (rc || (features & XFEATURE_MASK_XTILE) != XFEATURE_MASK_XTILE) {
+		ksft_print_msg("no AMX support\n");
+		return KSFT_SKIP;
+	}
+
 	check_cpuid_xtiledata();
 
 	init_stashed_xsave();
diff --git a/tools/testing/selftests/x86/lam.c b/tools/testing/selftests/x86/lam.c
index 215b8150b7cca..c0f016f45ee17 100644
--- a/tools/testing/selftests/x86/lam.c
+++ b/tools/testing/selftests/x86/lam.c
@@ -1183,7 +1183,7 @@ int main(int argc, char **argv)
 
 	if (!cpu_has_lam()) {
 		ksft_print_msg("Unsupported LAM feature!\n");
-		return -1;
+		return KSFT_SKIP;
 	}
 
 	while ((c = getopt(argc, argv, "ht:")) != -1) {
-- 
2.39.2