linux-kernel - Re: [PATCH 10 of 10] xen: mask out PWT too

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Date:	Wed, 09 Jan 2008 09:17:13 +0000
From:	"Jan Beulich" <jbeulich@...ell.com>
To:	"Jeremy Fitzhardinge" <jeremy@...p.org>
Cc:	"Ingo Molnar" <mingo@...e.hu>,
	"Glauber de Oliveira Costa" <glommer@...il.com>,
	"Andi Kleen" <ak@...e.de>, "LKML" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 10 of 10] xen: mask out PWT too

That's somewhat ugly, as it will need to be undone/modified for Dom0 and
physical device access support. Jan

>>> Jeremy Fitzhardinge <jeremy@...p.org> 08.01.08 23:00 >>>
The hypervisor doesn't allow PCD or PWT to be set on guest ptes, so
make sure they're masked out.  Also, fix up some previous mispatching.

Signed-off-by: Jeremy Fitzhardinge <jeremy@...source.com>

---
 arch/x86/xen/mmu.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -244,7 +244,7 @@ pte_t xen_make_pte(unsigned long long pt
 	if (pte & 1)
 		pte = phys_to_machine(XPADDR(pte)).maddr;
 
-	pte &= ~_PAGE_PCD;
+	pte &= ~(_PAGE_PCD | _PAGE_PWT);
 
 	return (pte_t){ .pte = pte };
 }
@@ -293,9 +293,7 @@ pte_t xen_make_pte(unsigned long pte)
 	if (pte & _PAGE_PRESENT)
 		pte = phys_to_machine(XPADDR(pte)).maddr;
 
-	pte &= ~_PAGE_PCD;
-
-	pte &= ~_PAGE_PCD;
+	pte &= ~(_PAGE_PCD | _PAGE_PWT);
 
 	return (pte_t){ pte };
 }



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