When a CPU does not have AMX, the test fails. But this is wrong as it
should be runnable regardless. Skip the test instead.
Also, simplify the feature check using arch_prctl() instead of CPUID. The
syscall is more trustworthy as the kernel controls the feature permission.
Reported-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Fixes: 6a3e0651b4a ("selftests/x86/amx: Add test cases for AMX state management")
Signed-off-by: Chang S. Bae <chang.seok.bae@xxxxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: linux-kselftest@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
Changes from v2: None
Changes from v1:
* Simplify the feature check code (Shuah Khan).
---
tools/testing/selftests/x86/amx.c | 31 ++++++++++---------------------
1 file changed, 10 insertions(+), 21 deletions(-)
diff --git a/tools/testing/selftests/x86/amx.c b/tools/testing/selftests/x86/amx.c
index d884fd69dd51..f0b1efe89ef7 100644
--- a/tools/testing/selftests/x86/amx.c
+++ b/tools/testing/selftests/x86/amx.c
@@ -101,24 +101,6 @@ static void clearhandler(int sig)
#define XFEATURE_MASK_XTILEDATA (1 << XFEATURE_XTILEDATA)
#define XFEATURE_MASK_XTILE (XFEATURE_MASK_XTILECFG | XFEATURE_MASK_XTILEDATA)
-#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;
static struct {
@@ -350,6 +332,7 @@ 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
@@ -928,10 +911,16 @@ static void test_ptrace(void)
int main(void)
{
- /* Check hardware availability at first */
- check_cpuid_xsave();
- check_cpuid_xtiledata();
+ unsigned long features;
+ long rc;
+ rc = syscall(SYS_arch_prctl, ARCH_GET_XCOMP_SUPP, &features);
+ if (rc || (features & XFEATURE_MASK_XTILE) != XFEATURE_MASK_XTILE) {
+ printf("[SKIP]\tno AMX support.\n");
+ exit(KSFT_FAIL);
+ }
+
+ check_cpuid_xtiledata();
init_stashed_xsave();
sethandler(SIGILL, handle_noperm, 0);
--
2.17.1
