selftests/x86/amx: Use provided __cpuid_count() macro

kselftest.h makes the __cpuid_count() macro available
to conveniently call the CPUID instruction.

Remove the local CPUID wrapper and use __cpuid_count()
from kselftest.h instead.

__cpuid_count() from kselftest.h is used instead of the
macro provided by the compiler since gcc v4.4 (via cpuid.h)
because the selftest needs to be supported with gcc v3.2,
the minimal required version for stable kernels.

Cc: Chang S. Bae <chang.seok.bae@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/x86/amx.c

@@ -17,6 +17,8 @@
 #include <sys/syscall.h>
 #include <sys/wait.h>
 
+#include "../kselftest.h" /* For __cpuid_count() */
+
 #ifndef __x86_64__
 # error This test is 64-bit only
 #endif
@@ -45,13 +47,6 @@ static inline uint64_t xgetbv(uint32_t index)
 	return eax + ((uint64_t)edx << 32);
 }
 
-static inline void cpuid(uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx)
-{
-	asm volatile("cpuid;"
-		     : "=a" (*eax), "=b" (*ebx), "=c" (*ecx), "=d" (*edx)
-		     : "0" (*eax), "2" (*ecx));
-}
-
 static inline void xsave(struct xsave_buffer *xbuf, uint64_t rfbm)
 {
 	uint32_t rfbm_lo = rfbm;
@@ -115,9 +110,7 @@ static inline void check_cpuid_xsave(void)
 	 * support for the XSAVE feature set, including
 	 * XGETBV.
 	 */
-	eax = 1;
-	ecx = 0;
-	cpuid(&eax, &ebx, &ecx, &edx);
+	__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))
@@ -140,9 +133,8 @@ static void check_cpuid_xtiledata(void)
 {
 	uint32_t eax, ebx, ecx, edx;
 
-	eax = CPUID_LEAF_XSTATE;
-	ecx = CPUID_SUBLEAF_XSTATE_USER;
-	cpuid(&eax, &ebx, &ecx, &edx);
+	__cpuid_count(CPUID_LEAF_XSTATE, CPUID_SUBLEAF_XSTATE_USER,
+		      eax, ebx, ecx, edx);
 
 	/*
 	 * EBX enumerates the size (in bytes) required by the XSAVE
@@ -153,10 +145,8 @@ static void check_cpuid_xtiledata(void)
 	 */
 	xbuf_size = ebx;
 
-	eax = CPUID_LEAF_XSTATE;
-	ecx = XFEATURE_XTILEDATA;
-
-	cpuid(&eax, &ebx, &ecx, &edx);
+	__cpuid_count(CPUID_LEAF_XSTATE, XFEATURE_XTILEDATA,
+		      eax, ebx, ecx, edx);
 	/*
 	 * eax: XTILEDATA state component size
 	 * ebx: XTILEDATA state component offset in user buffer