iommu/amd: Don't use 512GB pages

There is a bug in the hardware that will be triggered when
this page size is used. Make sure this does not happen.
Signed-off-by: Joerg Roedel <joro@8bytes.org>

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);