x86/mm: Create native_make_p4d() for PGTABLE_LEVELS <= 4

Currently, native_make_p4d() is only defined when CONFIG_PGTABLE_LEVELS
is greater than 4. Create a macro that will allow for defining and using
native_make_p4d() when CONFIG_PGTABLES_LEVELS is not greater than 4.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Larry Woodman <lwoodman@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Toshimitsu Kani <toshi.kani@hpe.com>
Cc: kasan-dev@googlegroups.com
Cc: kvm@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-efi@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/b645e14f9e73731023694494860ceab73feff777.1500319216.git.thomas.lendacky@amd.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/include/asm/pgtable_types.h

@@ -309,6 +309,11 @@ static inline p4dval_t native_p4d_val(p4d_t p4d)
 #else
 #include <asm-generic/pgtable-nop4d.h>
 
+static inline p4d_t native_make_p4d(pudval_t val)
+{
+	return (p4d_t) { .pgd = native_make_pgd((pgdval_t)val) };
+}
+
 static inline p4dval_t native_p4d_val(p4d_t p4d)
 {
 	return native_pgd_val(p4d.pgd);