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-rw-r--r--arch/x86/mm/init.c24
1 files changed, 22 insertions, 2 deletions
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 286d289b039b..37b8b0fe8320 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -81,6 +81,11 @@ static void __init find_early_table_space(unsigned long end, int use_pse,
end, pgt_buf_start << PAGE_SHIFT, pgt_buf_top << PAGE_SHIFT);
}
+void __init native_pagetable_reserve(u64 start, u64 end)
+{
+ memblock_x86_reserve_range(start, end, "PGTABLE");
+}
+
struct map_range {
unsigned long start;
unsigned long end;
@@ -272,9 +277,24 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
__flush_tlb_all();
+ /*
+ * Reserve the kernel pagetable pages we used (pgt_buf_start -
+ * pgt_buf_end) and free the other ones (pgt_buf_end - pgt_buf_top)
+ * so that they can be reused for other purposes.
+ *
+ * On native it just means calling memblock_x86_reserve_range, on Xen it
+ * also means marking RW the pagetable pages that we allocated before
+ * but that haven't been used.
+ *
+ * In fact on xen we mark RO the whole range pgt_buf_start -
+ * pgt_buf_top, because we have to make sure that when
+ * init_memory_mapping reaches the pagetable pages area, it maps
+ * RO all the pagetable pages, including the ones that are beyond
+ * pgt_buf_end at that time.
+ */
if (!after_bootmem && pgt_buf_end > pgt_buf_start)
- memblock_x86_reserve_range(pgt_buf_start << PAGE_SHIFT,
- pgt_buf_end << PAGE_SHIFT, "PGTABLE");
+ x86_init.mapping.pagetable_reserve(PFN_PHYS(pgt_buf_start),
+ PFN_PHYS(pgt_buf_end));
if (!after_bootmem)
early_memtest(start, end);