linux-kernel - [PATCH] [224/275] xen: set max_pfn

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Message-Id: <20110330210749.8A6653E1A05@tassilo.jf.intel.com>
Date:	Wed, 30 Mar 2011 14:07:49 -0700 (PDT)
From:	Andi Kleen <andi@...stfloor.org>
To:	stefano.stabellini@...citrix.com, konrad.wilk@...cle.com,
	ak@...ux.intel.com, hpa@...or.com, gregkh@...e.de,
	linux-kernel@...r.kernel.org, stable@...nel.org,
	tim.bird@...sony.com
Subject: [PATCH] [224/275] xen: set max_pfn_mapped to the last pfn mapped

2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------
From: Stefano Stabellini <stefano.stabellini@...citrix.com>

commit 14988a4d350ce3b41ecad4f63c4f44c56f5ae34d upstream.

Do not set max_pfn_mapped to the end of the initial memory mappings,
that also contain pages that don't belong in pfn space (like the mfn
list).

Set max_pfn_mapped to the last real pfn mapped in the initial memory
mappings that is the pfn backing _end.

Signed-off-by: Stefano Stabellini <stefano.stabellini@...citrix.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Signed-off-by: Andi Kleen <ak@...ux.intel.com>
LKML-Reference: <alpine.DEB.2.00.1103171739050.3382@...all-desktop>
Signed-off-by: H. Peter Anvin <hpa@...or.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 arch/x86/xen/mmu.c |   13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

Index: linux-2.6.35.y/arch/x86/xen/mmu.c
===================================================================
--- linux-2.6.35.y.orig/arch/x86/xen/mmu.c	2011-03-29 22:50:26.784573069 -0700
+++ linux-2.6.35.y/arch/x86/xen/mmu.c	2011-03-29 23:03:02.900225961 -0700
@@ -1641,9 +1641,6 @@
 		for (pteidx = 0; pteidx < PTRS_PER_PTE; pteidx++, pfn++) {
 			pte_t pte;
 
-			if (pfn > max_pfn_mapped)
-				max_pfn_mapped = pfn;
-
 			if (!pte_none(pte_page[pteidx]))
 				continue;
 
@@ -1687,6 +1684,12 @@
 	pud_t *l3;
 	pmd_t *l2;
 
+	/* max_pfn_mapped is the last pfn mapped in the initial memory
+	 * mappings. Considering that on Xen after the kernel mappings we
+	 * have the mappings of some pages that don't exist in pfn space, we
+	 * set max_pfn_mapped to the last real pfn mapped. */
+	max_pfn_mapped = PFN_DOWN(__pa(xen_start_info->mfn_list));
+
 	/* Zap identity mapping */
 	init_level4_pgt[0] = __pgd(0);
 
@@ -1750,9 +1753,7 @@
 {
 	pmd_t *kernel_pmd;
 
-	max_pfn_mapped = PFN_DOWN(__pa(xen_start_info->pt_base) +
-				  xen_start_info->nr_pt_frames * PAGE_SIZE +
-				  512*1024);
+	max_pfn_mapped = PFN_DOWN(__pa(xen_start_info->mfn_list));
 
 	kernel_pmd = m2v(pgd[KERNEL_PGD_BOUNDARY].pgd);
 	memcpy(level2_kernel_pgt, kernel_pmd, sizeof(pmd_t) * PTRS_PER_PMD);
--
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