linux-kernel - [PATCH] x86-64: also clear _PAGE_GLOBAL from __supported_pte_mask if !cpu_has

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Date:	Fri, 23 Jan 2015 08:35:13 +0000
From:	"Jan Beulich" <JBeulich@...e.com>
To:	<mingo@...e.hu>, <tglx@...utronix.de>, <hpa@...or.com>
Cc:	<linux-kernel@...r.kernel.org>
Subject: [PATCH] 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@...e.com>
---
 arch/x86/mm/init.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- 3.19-rc5/arch/x86/mm/init.c
+++ 3.19-rc5-x86_64-clear-PAGE_GLOBAL/arch/x86/mm/init.c
@@ -179,7 +179,8 @@ static void __init probe_page_size_mask(
 	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



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