linux-kernel - [03/35] xen: partially revert "xen: set max_pfn

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Date:	Fri, 08 Jul 2011 15:49:52 -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>
Subject: [03/35] xen: partially revert "xen: set max_pfn_mapped to the last pfn mapped"

2.6.32-longterm review patch.  If anyone has any objections, please let us 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>

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

--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1658,6 +1658,11 @@ 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;
 
@@ -1770,7 +1775,9 @@ __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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