[PATCH v2] selftests/mm: Skip test for non-LPA2 and non-LVA systems

[Dev Jain <dev.jain@arm.com>]

Post my improvement of the test:
https://lore.kernel.org/all/20240522070435.773918-3-dev.jain@arm.com/
The test begins to fail on 4k and 16k pages, on non-LPA2 systems. To
reduce noise in the CI systems, let us skip the test when higher address
space is not implemented.

v1->v2:
 - Guard with ifdeffery to prevent compiler warning on other arches

Signed-off-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
---
The patch applies on linux-next.

 tools/testing/selftests/mm/va_high_addr_switch.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/mm/va_high_addr_switch.c b/tools/testing/selftests/mm/va_high_addr_switch.c
index fa7eabfaf841..896b3f73fc53 100644
--- a/tools/testing/selftests/mm/va_high_addr_switch.c
+++ b/tools/testing/selftests/mm/va_high_addr_switch.c
@@ -293,6 +293,20 @@ static int run_test(struct testcase *test, int count)
 	return ret;
 }
 
+#ifdef __aarch64__
+/* Check if userspace VA > 48 bits */
+static int high_address_present(void)
+{
+	void *ptr = mmap((void *)(1UL << 50), 1, PROT_READ | PROT_WRITE,
+			 MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
+	if (ptr == MAP_FAILED)
+		return 0;
+
+	munmap(ptr, 1);
+	return 1;
+}
+#endif
+
 static int supported_arch(void)
 {
 #if defined(__powerpc64__)
@@ -300,7 +314,7 @@ static int supported_arch(void)
 #elif defined(__x86_64__)
 	return 1;
 #elif defined(__aarch64__)
-	return 1;
+	return high_address_present();
 #else
 	return 0;
 #endif
-- 
2.34.1