1 files changed, 50 insertions, 24 deletions

diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 8b08fb955274..9127e31c7268 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -30,7 +30,7 @@
 #ifdef CONFIG_X86_PAT
 int __read_mostly pat_enabled = 1;
 
-void __cpuinit pat_disable(char *reason)
+void __cpuinit pat_disable(const char *reason)
 {
         pat_enabled = 0;
         printk(KERN_INFO "%s\n", reason);
@@ -42,6 +42,11 @@ static int __init nopat(char *str)
         return 0;
 }
 early_param("nopat", nopat);
+#else
+static inline void pat_disable(const char *reason)
+{
+        (void)reason;
+}
 #endif
 
 
@@ -78,16 +83,20 @@ void pat_init(void)
         if (!pat_enabled)
                 return;
 
-        /* Paranoia check. */
-        if (!cpu_has_pat && boot_pat_state) {
-                /*
-                 * If this happens we are on a secondary CPU, but
-                 * switched to PAT on the boot CPU. We have no way to
-                 * undo PAT.
-                 */
-                printk(KERN_ERR "PAT enabled, "
-                       "but not supported by secondary CPU\n");
-                BUG();
+        if (!cpu_has_pat) {
+                if (!boot_pat_state) {
+                        pat_disable("PAT not supported by CPU.");
+                        return;
+                } else {
+                        /*
+                         * If this happens we are on a secondary CPU, but
+                         * switched to PAT on the boot CPU. We have no way to
+                         * undo PAT.
+                         */
+                        printk(KERN_ERR "PAT enabled, "
+                               "but not supported by secondary CPU\n");
+                        BUG();
+                }
         }
 
         /* Set PWT to Write-Combining. All other bits stay the same */
@@ -333,11 +342,23 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type,
                                               req_type & _PAGE_CACHE_MASK);
         }
 
-        is_range_ram = pagerange_is_ram(start, end);
-        if (is_range_ram == 1)
-                return reserve_ram_pages_type(start, end, req_type, new_type);
-        else if (is_range_ram < 0)
-                return -EINVAL;
+        if (new_type)
+                *new_type = actual_type;
+
+        /*
+         * For legacy reasons, some parts of the physical address range in the
+         * legacy 1MB region is treated as non-RAM (even when listed as RAM in
+         * the e820 tables).  So we will track the memory attributes of this
+         * legacy 1MB region using the linear memtype_list always.
+         */
+        if (end >= ISA_END_ADDRESS) {
+                is_range_ram = pagerange_is_ram(start, end);
+                if (is_range_ram == 1)
+                        return reserve_ram_pages_type(start, end, req_type,
+                                                      new_type);
+                else if (is_range_ram < 0)
+                        return -EINVAL;
+        }
 
         new  = kmalloc(sizeof(struct memtype), GFP_KERNEL);
         if (!new)
@@ -347,9 +368,6 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type,
         new->end        = end;
         new->type       = actual_type;
 
-        if (new_type)
-                *new_type = actual_type;
-
         spin_lock(&memtype_lock);
 
         if (cached_entry && start >= cached_start)
@@ -437,11 +455,19 @@ int free_memtype(u64 start, u64 end)
         if (is_ISA_range(start, end - 1))
                 return 0;
 
-        is_range_ram = pagerange_is_ram(start, end);
-        if (is_range_ram == 1)
-                return free_ram_pages_type(start, end);
-        else if (is_range_ram < 0)
-                return -EINVAL;
+        /*
+         * For legacy reasons, some parts of the physical address range in the
+         * legacy 1MB region is treated as non-RAM (even when listed as RAM in
+         * the e820 tables).  So we will track the memory attributes of this
+         * legacy 1MB region using the linear memtype_list always.
+         */
+        if (end >= ISA_END_ADDRESS) {
+                is_range_ram = pagerange_is_ram(start, end);
+                if (is_range_ram == 1)
+                        return free_ram_pages_type(start, end);
+                else if (is_range_ram < 0)
+                        return -EINVAL;
+        }
 
         spin_lock(&memtype_lock);
         list_for_each_entry(entry, &memtype_list, nd) {