x86-64: Also clear _PAGE_GLOBAL from __supported_pte_mask if !cpu_has_pge

Not just setting it when the feature is available is for
consistency, and may allow Xen to drop its custom clearing of
the flag (unless it needs it cleared earlier than this code
executes). Note that the change is benign to ix86, as the flag
starts out clear there.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/54C215D10200007800058912@mail.emea.novell.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/mm/init.c

@@ -179,7 +179,8 @@ static void __init probe_page_size_mask(void)
 	if (cpu_has_pge) {
 		set_in_cr4(X86_CR4_PGE);
 		__supported_pte_mask |= _PAGE_GLOBAL;
-	}
+	} else
+		__supported_pte_mask &= ~_PAGE_GLOBAL;
 }
 
 #ifdef CONFIG_X86_32