[PATCH RFC v2 9/9] selftests/x86/apx: Add APX test

["Chang S. Bae" <chang.seok.bae@intel.com>]

The extended general-purpose registers for APX may contain random data,
which is currently assumed by the xstate testing framework. This allows
the testing of the new userspace feature using the common test code.

Invoke the test entry function from apx.c after enumerating the
state component and adding it to the support list

Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
---
The patch depends on the selftest xstate series, which was just merged
into the x86/fpu branch as of now:
  https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/log/?h=x86/fpu

Here is the original series posting for the record:
  https://lore.kernel.org/lkml/20250226010731.2456-1-chang.seok.bae@intel.com/
---
 tools/testing/selftests/x86/Makefile |  3 ++-
 tools/testing/selftests/x86/apx.c    | 10 ++++++++++
 tools/testing/selftests/x86/xstate.c |  3 ++-
 tools/testing/selftests/x86/xstate.h |  2 ++
 4 files changed, 16 insertions(+), 2 deletions(-)
 create mode 100644 tools/testing/selftests/x86/apx.c

diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile
index 28422c32cc8f..f703fcfe9f7c 100644
--- a/tools/testing/selftests/x86/Makefile
+++ b/tools/testing/selftests/x86/Makefile
@@ -19,7 +19,7 @@ TARGETS_C_32BIT_ONLY := entry_from_vm86 test_syscall_vdso unwind_vdso \
 			test_FCMOV test_FCOMI test_FISTTP \
 			vdso_restorer
 TARGETS_C_64BIT_ONLY := fsgsbase sysret_rip syscall_numbering \
-			corrupt_xstate_header amx lam test_shadow_stack avx
+			corrupt_xstate_header amx lam test_shadow_stack avx apx
 # Some selftests require 32bit support enabled also on 64bit systems
 TARGETS_C_32BIT_NEEDED := ldt_gdt ptrace_syscall
 
@@ -136,3 +136,4 @@ $(OUTPUT)/nx_stack_64: CFLAGS += -Wl,-z,noexecstack
 $(OUTPUT)/avx_64: CFLAGS += -mno-avx -mno-avx512f
 $(OUTPUT)/amx_64: EXTRA_FILES += xstate.c
 $(OUTPUT)/avx_64: EXTRA_FILES += xstate.c
+$(OUTPUT)/apx_64: EXTRA_FILES += xstate.c
diff --git a/tools/testing/selftests/x86/apx.c b/tools/testing/selftests/x86/apx.c
new file mode 100644
index 000000000000..d9c8d41b8c5a
--- /dev/null
+++ b/tools/testing/selftests/x86/apx.c
@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#define _GNU_SOURCE
+
+#include "xstate.h"
+
+int main(void)
+{
+	test_xstate(XFEATURE_APX);
+}
diff --git a/tools/testing/selftests/x86/xstate.c b/tools/testing/selftests/x86/xstate.c
index 23c1d6c964ea..97fe4bd8bc77 100644
--- a/tools/testing/selftests/x86/xstate.c
+++ b/tools/testing/selftests/x86/xstate.c
@@ -31,7 +31,8 @@
 	 (1 << XFEATURE_OPMASK)	|	\
 	 (1 << XFEATURE_ZMM_Hi256) |	\
 	 (1 << XFEATURE_Hi16_ZMM) |	\
-	 (1 << XFEATURE_XTILEDATA))
+	 (1 << XFEATURE_XTILEDATA) |	\
+	 (1 << XFEATURE_APX))
 
 static inline uint64_t xgetbv(uint32_t index)
 {
diff --git a/tools/testing/selftests/x86/xstate.h b/tools/testing/selftests/x86/xstate.h
index 42af36ec852f..e91e3092b5d2 100644
--- a/tools/testing/selftests/x86/xstate.h
+++ b/tools/testing/selftests/x86/xstate.h
@@ -33,6 +33,7 @@ enum xfeature {
 	XFEATURE_RSRVD_COMP_16,
 	XFEATURE_XTILECFG,
 	XFEATURE_XTILEDATA,
+	XFEATURE_APX,
 
 	XFEATURE_MAX,
 };
@@ -59,6 +60,7 @@ static const char *xfeature_names[] =
 	"unknown xstate feature",
 	"AMX Tile config",
 	"AMX Tile data",
+	"APX registers",
 	"unknown xstate feature",
 };
 
-- 
2.45.2