diff --git a/[refs] b/[refs]
index eed18ecc73bb..1e19f4766685 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 78bfa9f395f6bbab168b83f69b99659818517b02
+refs/heads/master: 954e3dd8308501bb00cae4ed655968282dc65314
diff --git a/trunk/drivers/iommu/amd_iommu.c b/trunk/drivers/iommu/amd_iommu.c
index cb63cc5d94d7..98d74ab564b6 100644
--- a/trunk/drivers/iommu/amd_iommu.c
+++ b/trunk/drivers/iommu/amd_iommu.c
@@ -66,8 +66,10 @@
  *
  * If at some point we'd like to utilize the IOMMU core's new behavior,
  * we could change this to advertise the real page sizes we support.
+ *
+ * 512GB Pages are not supported due to a hardware bug
  */
-#define AMD_IOMMU_PGSIZES	(~0xFFFUL)
+#define AMD_IOMMU_PGSIZES	((~0xFFFUL) & ~(2ULL << 38))
 
 static DEFINE_RWLOCK(amd_iommu_devtable_lock);