From: Jan Beulich <jbeulich@suse.com>
Subject: AMD/IOMMU: abstract maximum number of page table levels

We will want to use the constant elsewhere.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Paul Durrant <paul@xen.org>

--- a/xen/include/asm-x86/hvm/svm/amd-iommu-proto.h
+++ b/xen/include/asm-x86/hvm/svm/amd-iommu-proto.h
@@ -185,7 +185,7 @@ static inline int amd_iommu_get_paging_m
     while ( max_frames > PTE_PER_TABLE_SIZE )
     {
         max_frames = PTE_PER_TABLE_ALIGN(max_frames) >> PTE_PER_TABLE_SHIFT;
-        if ( ++level > 6 )
+        if ( ++level > IOMMU_MAX_PT_LEVELS )
             return -ENOMEM;
     }
 
--- a/xen/include/asm-x86/hvm/svm/amd-iommu-defs.h
+++ b/xen/include/asm-x86/hvm/svm/amd-iommu-defs.h
@@ -114,6 +114,8 @@
 #define IOMMU_DEV_TABLE_PAGE_TABLE_PTR_LOW_MASK		0xFFFFF000
 #define IOMMU_DEV_TABLE_PAGE_TABLE_PTR_LOW_SHIFT	12
 
+#define IOMMU_MAX_PT_LEVELS 6
+
 /* DeviceTable Entry[63:32] */
 #define IOMMU_DEV_TABLE_GV_SHIFT                    23
 #define IOMMU_DEV_TABLE_GV_MASK                     0x800000
--- a/xen/drivers/passthrough/amd/iommu_map.c
+++ b/xen/drivers/passthrough/amd/iommu_map.c
@@ -477,7 +477,7 @@ static int iommu_pde_from_dfn(struct dom
     table = hd->arch.root_table;
     level = hd->arch.paging_mode;
 
-    BUG_ON( table == NULL || level < 1 || level > 6 );
+    BUG_ON( table == NULL || level < 1 || level > IOMMU_MAX_PT_LEVELS );
 
     /*
      * A frame number past what the current page tables can represent can't