xen: partially revert "xen: set max_pfn_mapped to the last pfn mapped"

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@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 356a79904b9ba72af5dfe08d7308dbbe75edeecd..3f90a2ceff81a734c0209f688cdcfe71f7ec67d5 100644 (file)
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1658,6 +1658,11 @@ static __init void xen_map_identity_early(pmd_t *pmd, unsigned long max_pfn)
                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(pgd_t *pgd,
 {
        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);