linux-kernel - [17/55] xen: set max_pfn_mapped to the last pfn mapped

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Message-Id: <20110325234840.708520164@clark.kroah.org>
Date:	Fri, 25 Mar 2011 16:47:10 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Stefano Stabellini <stefano.stabellini@...citrix.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: [17/55] xen: set max_pfn_mapped to the last pfn mapped

2.6.37-stable review patch.  If anyone has any objections, please let us 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>
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(-)

--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -2027,9 +2027,6 @@ static __init void xen_map_identity_earl
 		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;
 
@@ -2087,6 +2084,12 @@ __init pgd_t *xen_setup_kernel_pagetable
 	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);
 
@@ -2191,9 +2194,7 @@ __init pgd_t *xen_setup_kernel_pagetable
 	initial_kernel_pmd =
 		extend_brk(sizeof(pmd_t) * PTRS_PER_PMD, PAGE_SIZE);
 
-	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(initial_kernel_pmd, kernel_pmd, sizeof(pmd_t) * PTRS_PER_PMD);


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