linux-kernel - [PATCH] [67/99] xen: partially revert "xen: set max_pfn

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Date:	Wed, 27 Jul 2011 14:49:06 -0700 (PDT)
From:	Andi Kleen <andi@...stfloor.org>
To:	stefano.stabellini@...citrix.com, konrad.wilk@...cle.com,
	gregkh@...e.de, ak@...ux.intel.com, linux-kernel@...r.kernel.org,
	stable@...nel.org, tim.bird@...sony.com
Subject: [PATCH] [67/99] xen: partially revert "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 a91d92875ee94e4703fd017ccaadb48cfb344994 upstream.

We only need to set max_pfn_mapped to the last pfn mapped on x86_64 to
make sure that cleanup_highmap doesn't remove important mappings at
_end.

We don't need to do this on x86_32 because cleanup_highmap is not called
on x86_32. Besides lowering max_pfn_mapped on x86_32 has the unwanted
side effect of limiting the amount of memory available for the 1:1
kernel pagetable allocation.

This patch reverts the x86_32 part of the original patch.

Signed-off-by: Stefano Stabellini <stefano.stabellini@...citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
Signed-off-by: Andi Kleen <ak@...ux.intel.com>

---
 arch/x86/xen/mmu.c |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

Index: linux-2.6.35.y/arch/x86/xen/mmu.c
===================================================================
--- linux-2.6.35.y.orig/arch/x86/xen/mmu.c
+++ linux-2.6.35.y/arch/x86/xen/mmu.c
@@ -1641,6 +1641,11 @@ static __init void xen_map_identity_earl
 		for (pteidx = 0; pteidx < PTRS_PER_PTE; pteidx++, pfn++) {
 			pte_t pte;
 
+#ifdef CONFIG_X86_32
+			if (pfn > max_pfn_mapped)
+				max_pfn_mapped = pfn;
+#endif
+
 			if (!pte_none(pte_page[pteidx]))
 				continue;
 
@@ -1753,7 +1758,9 @@ __init pgd_t *xen_setup_kernel_pagetable
 {
 	pmd_t *kernel_pmd;
 
-	max_pfn_mapped = PFN_DOWN(__pa(xen_start_info->mfn_list));
+	max_pfn_mapped = PFN_DOWN(__pa(xen_start_info->pt_base) +
+				  xen_start_info->nr_pt_frames * PAGE_SIZE +
+				  512*1024);
 
 	kernel_pmd = m2v(pgd[KERNEL_PGD_BOUNDARY].pgd);
 	memcpy(level2_kernel_pgt, kernel_pmd, sizeof(pmd_t) * PTRS_PER_PMD);
--
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