x86: reserve SLIT

save the SLIT, in case we are using fixmap to read it, and that fixmap
could be cleared by others.
Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/mm/srat_64.c

@@ -100,7 +100,19 @@ static __init inline int srat_disabled(void)
 /* Callback for SLIT parsing */
 void __init acpi_numa_slit_init(struct acpi_table_slit *slit)
 {
-	acpi_slit = slit;
+	unsigned length;
+	unsigned long phys;
+
+	length = slit->header.length;
+	phys = find_e820_area(0, max_pfn_mapped<<PAGE_SHIFT, length,
+		 PAGE_SIZE);
+
+	if (phys == -1L)
+		panic(" Can not save slit!\n");
+
+	acpi_slit = __va(phys);
+	memcpy(acpi_slit, slit, length);
+	reserve_early(phys, phys + length, "ACPI SLIT");
 }
 
 /* Callback for Proximity Domain -> LAPIC mapping */