1 files changed, 91 insertions, 47 deletions

diff --git a/arch/i386/mm/init.c b/arch/i386/mm/init.c
index bd5ef3718504..e8545dcf06c5 100644
--- a/arch/i386/mm/init.c
+++ b/arch/i386/mm/init.c
@@ -43,6 +43,7 @@
 #include <asm/tlb.h>
 #include <asm/tlbflush.h>
 #include <asm/sections.h>
+#include <asm/paravirt.h>
 
 unsigned int __VMALLOC_RESERVE = 128 << 20;
 
@@ -62,17 +63,18 @@ static pmd_t * __init one_md_table_init(pgd_t *pgd)
         pmd_t *pmd_table;
                 
 #ifdef CONFIG_X86_PAE
-        pmd_table = (pmd_t *) alloc_bootmem_low_pages(PAGE_SIZE);
-        paravirt_alloc_pd(__pa(pmd_table) >> PAGE_SHIFT);
-        set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
-        pud = pud_offset(pgd, 0);
-        if (pmd_table != pmd_offset(pud, 0)) 
-                BUG();
-#else
+        if (!(pgd_val(*pgd) & _PAGE_PRESENT)) {
+                pmd_table = (pmd_t *) alloc_bootmem_low_pages(PAGE_SIZE);
+
+                paravirt_alloc_pd(__pa(pmd_table) >> PAGE_SHIFT);
+                set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
+                pud = pud_offset(pgd, 0);
+                if (pmd_table != pmd_offset(pud, 0))
+                        BUG();
+        }
+#endif
         pud = pud_offset(pgd, 0);
         pmd_table = pmd_offset(pud, 0);
-#endif
-
         return pmd_table;
 }
 
@@ -82,14 +84,12 @@ static pmd_t * __init one_md_table_init(pgd_t *pgd)
  */
 static pte_t * __init one_page_table_init(pmd_t *pmd)
 {
-        if (pmd_none(*pmd)) {
+        if (!(pmd_val(*pmd) & _PAGE_PRESENT)) {
                 pte_t *page_table = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
+
                 paravirt_alloc_pt(__pa(page_table) >> PAGE_SHIFT);
                 set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
-                if (page_table != pte_offset_kernel(pmd, 0))
-                        BUG();  
-
-                return page_table;
+                BUG_ON(page_table != pte_offset_kernel(pmd, 0));
         }
         
         return pte_offset_kernel(pmd, 0);
@@ -109,7 +109,6 @@ static pte_t * __init one_page_table_init(pmd_t *pmd)
 static void __init page_table_range_init (unsigned long start, unsigned long end, pgd_t *pgd_base)
 {
         pgd_t *pgd;
-        pud_t *pud;
         pmd_t *pmd;
         int pgd_idx, pmd_idx;
         unsigned long vaddr;
@@ -120,13 +119,10 @@ static void __init page_table_range_init (unsigned long start, unsigned long end
         pgd = pgd_base + pgd_idx;
 
         for ( ; (pgd_idx < PTRS_PER_PGD) && (vaddr != end); pgd++, pgd_idx++) {
-                if (pgd_none(*pgd)) 
-                        one_md_table_init(pgd);
-                pud = pud_offset(pgd, vaddr);
-                pmd = pmd_offset(pud, vaddr);
+                pmd = one_md_table_init(pgd);
+                pmd = pmd + pmd_index(vaddr);
                 for (; (pmd_idx < PTRS_PER_PMD) && (vaddr != end); pmd++, pmd_idx++) {
-                        if (pmd_none(*pmd)) 
-                                one_page_table_init(pmd);
+                        one_page_table_init(pmd);
 
                         vaddr += PMD_SIZE;
                 }
@@ -168,20 +164,22 @@ static void __init kernel_physical_mapping_init(pgd_t *pgd_base)
                         /* Map with big pages if possible, otherwise create normal page tables. */
                         if (cpu_has_pse) {
                                 unsigned int address2 = (pfn + PTRS_PER_PTE - 1) * PAGE_SIZE + PAGE_OFFSET + PAGE_SIZE-1;
-
                                 if (is_kernel_text(address) || is_kernel_text(address2))
                                         set_pmd(pmd, pfn_pmd(pfn, PAGE_KERNEL_LARGE_EXEC));
                                 else
                                         set_pmd(pmd, pfn_pmd(pfn, PAGE_KERNEL_LARGE));
+
                                 pfn += PTRS_PER_PTE;
                         } else {
                                 pte = one_page_table_init(pmd);
 
-                                for (pte_ofs = 0; pte_ofs < PTRS_PER_PTE && pfn < max_low_pfn; pte++, pfn++, pte_ofs++) {
-                                                if (is_kernel_text(address))
-                                                        set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC));
-                                                else
-                                                        set_pte(pte, pfn_pte(pfn, PAGE_KERNEL));
+                                for (pte_ofs = 0;
+                                     pte_ofs < PTRS_PER_PTE && pfn < max_low_pfn;
+                                     pte++, pfn++, pte_ofs++, address += PAGE_SIZE) {
+                                        if (is_kernel_text(address))
+                                                set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC));
+                                        else
+                                                set_pte(pte, pfn_pte(pfn, PAGE_KERNEL));
                                 }
                         }
                 }
@@ -338,24 +336,78 @@ extern void __init remap_numa_kva(void);
 #define remap_numa_kva() do {} while (0)
 #endif
 
-static void __init pagetable_init (void)
+void __init native_pagetable_setup_start(pgd_t *base)
 {
-        unsigned long vaddr;
-        pgd_t *pgd_base = swapper_pg_dir;
-
 #ifdef CONFIG_X86_PAE
         int i;
-        /* Init entries of the first-level page table to the zero page */
-        for (i = 0; i < PTRS_PER_PGD; i++)
-                set_pgd(pgd_base + i, __pgd(__pa(empty_zero_page) | _PAGE_PRESENT));
+
+        /*
+         * Init entries of the first-level page table to the
+         * zero page, if they haven't already been set up.
+         *
+         * In a normal native boot, we'll be running on a
+         * pagetable rooted in swapper_pg_dir, but not in PAE
+         * mode, so this will end up clobbering the mappings
+         * for the lower 24Mbytes of the address space,
+         * without affecting the kernel address space.
+         */
+        for (i = 0; i < USER_PTRS_PER_PGD; i++)
+                set_pgd(&base[i],
+                        __pgd(__pa(empty_zero_page) | _PAGE_PRESENT));
+
+        /* Make sure kernel address space is empty so that a pagetable
+           will be allocated for it. */
+        memset(&base[USER_PTRS_PER_PGD], 0,
+               KERNEL_PGD_PTRS * sizeof(pgd_t));
 #else
         paravirt_alloc_pd(__pa(swapper_pg_dir) >> PAGE_SHIFT);
 #endif
+}
+
+void __init native_pagetable_setup_done(pgd_t *base)
+{
+#ifdef CONFIG_X86_PAE
+        /*
+         * Add low memory identity-mappings - SMP needs it when
+         * starting up on an AP from real-mode. In the non-PAE
+         * case we already have these mappings through head.S.
+         * All user-space mappings are explicitly cleared after
+         * SMP startup.
+         */
+        set_pgd(&base[0], base[USER_PTRS_PER_PGD]);
+#endif
+}
+
+/*
+ * Build a proper pagetable for the kernel mappings.  Up until this
+ * point, we've been running on some set of pagetables constructed by
+ * the boot process.
+ *
+ * If we're booting on native hardware, this will be a pagetable
+ * constructed in arch/i386/kernel/head.S, and not running in PAE mode
+ * (even if we'll end up running in PAE).  The root of the pagetable
+ * will be swapper_pg_dir.
+ *
+ * If we're booting paravirtualized under a hypervisor, then there are
+ * more options: we may already be running PAE, and the pagetable may
+ * or may not be based in swapper_pg_dir.  In any case,
+ * paravirt_pagetable_setup_start() will set up swapper_pg_dir
+ * appropriately for the rest of the initialization to work.
+ *
+ * In general, pagetable_init() assumes that the pagetable may already
+ * be partially populated, and so it avoids stomping on any existing
+ * mappings.
+ */
+static void __init pagetable_init (void)
+{
+        unsigned long vaddr, end;
+        pgd_t *pgd_base = swapper_pg_dir;
+
+        paravirt_pagetable_setup_start(pgd_base);
 
         /* Enable PSE if available */
-        if (cpu_has_pse) {
+        if (cpu_has_pse)
                 set_in_cr4(X86_CR4_PSE);
-        }
 
         /* Enable PGE if available */
         if (cpu_has_pge) {
@@ -372,20 +424,12 @@ static void __init pagetable_init (void)
          * created - mappings will be set by set_fixmap():
          */
         vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
-        page_table_range_init(vaddr, 0, pgd_base);
+        end = (FIXADDR_TOP + PMD_SIZE - 1) & PMD_MASK;
+        page_table_range_init(vaddr, end, pgd_base);
 
         permanent_kmaps_init(pgd_base);
 
-#ifdef CONFIG_X86_PAE
-        /*
-         * Add low memory identity-mappings - SMP needs it when
-         * starting up on an AP from real-mode. In the non-PAE
-         * case we already have these mappings through head.S.
-         * All user-space mappings are explicitly cleared after
-         * SMP startup.
-         */
-        set_pgd(&pgd_base[0], pgd_base[USER_PTRS_PER_PGD]);
-#endif
+        paravirt_pagetable_setup_done(pgd_base);
 }
 
 #if defined(CONFIG_SOFTWARE_SUSPEND) || defined(CONFIG_ACPI_SLEEP)