linux-kernel - [PATCH 04/10] xen/mmu: For 1-1 mapping, automatically set _PAGE

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Date:	Tue, 21 Dec 2010 16:37:34 -0500
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	linux-kernel@...r.kernel.org, jeremy@...p.org, hpa@...or.com
Cc:	Jan Beulich <JBeulich@...ell.com>, xen-devel@...ts.xensource.com,
	Konrad Rzeszutek Wilk <konrad@...nel.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Subject: [PATCH 04/10] xen/mmu: For 1-1 mapping, automatically set _PAGE_IOMAP.

This means that for PFNs (specifically: those in any E820 gaps
or non-RAM E820 regions) that have 1-1 mapping we set the
_PAGE_IOMAP flag.

Later on we could remove the _PAGE_IOMAP code handling, but
for right now lets keep this in to not introduce any bisection
failures across this patchset.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
---
 arch/x86/xen/mmu.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 4ba7e4e..bd02e7d 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -832,6 +832,9 @@ static pteval_t pte_pfn_to_mfn(pteval_t val)
 		pteval_t flags = val & PTE_FLAGS_MASK;
 		unsigned long mfn = pfn_to_mfn(pfn);
 
+		if (mfn == pfn)
+			flags |= _PAGE_IOMAP;
+
 		/*
 		 * If there's no mfn for the pfn, then just create an
 		 * empty non-present pte.  Unfortunately this loses
-- 
1.7.1

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