1 files changed, 4 insertions, 0 deletions

diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 738fd0f24958..eb1bf000d12e 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -481,12 +481,16 @@ static inline int range_is_allowed(unsigned long pfn, unsigned long size)
         return 1;
 }
 #else
+/* This check is needed to avoid cache aliasing when PAT is enabled */
 static inline int range_is_allowed(unsigned long pfn, unsigned long size)
 {
         u64 from = ((u64)pfn) << PAGE_SHIFT;
         u64 to = from + size;
         u64 cursor = from;
 
+        if (!pat_enabled)
+                return 1;
+
         while (cursor < to) {
                 if (!devmem_is_allowed(pfn)) {
                         printk(KERN_INFO