xen: set max_pfn_mapped to the last pfn mapped

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@eu.citrix.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
LKML-Reference: <alpine.DEB.2.00.1103171739050.3382@kaball-desktop>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 914f04695ce5e1a917e786ab2ac231369083ec1e..6adff931d5f3f371a872d7715b5f4c22b3085aaa 100644 (file)
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1641,9 +1641,6 @@ 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;
 
-                       if (pfn > max_pfn_mapped)
-                               max_pfn_mapped = pfn;
-
                        if (!pte_none(pte_page[pteidx]))
                                continue;
 
@@ -1687,6 +1684,12 @@ __init pgd_t *xen_setup_kernel_pagetable(pgd_t *pgd,
        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 @@ __init pgd_t *xen_setup_kernel_pagetable(pgd_t *pgd,
 {
        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);