[xen stable-4.15] AMD/IOMMU: abstract maximum number of page table levels

[patchbot@xxxxxxx]

commit ed84ea00e0e53c5fb9776034ef43d3048cae8362
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Apr 5 15:00:55 2022 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Apr 5 15:00:55 2022 +0200

    AMD/IOMMU: abstract maximum number of page table levels
    
    We will want to use the constant elsewhere.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Paul Durrant <paul@xxxxxxx>
    master commit: a038b514c1e970a8dc32229cbd31f6769ee61ad5
    master date: 2022-04-05 14:20:04 +0200
---
 xen/drivers/passthrough/amd/iommu-defs.h | 1 +
 xen/drivers/passthrough/amd/iommu.h      | 2 +-
 xen/drivers/passthrough/amd/iommu_map.c  | 2 +-
 3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/xen/drivers/passthrough/amd/iommu-defs.h 
b/xen/drivers/passthrough/amd/iommu-defs.h
index 0c97db2a32..8810e497b9 100644
--- a/xen/drivers/passthrough/amd/iommu-defs.h
+++ b/xen/drivers/passthrough/amd/iommu-defs.h
@@ -106,6 +106,7 @@ struct amd_iommu_dte {
     bool tv:1;
     unsigned int :5;
     unsigned int had:2;
+#define IOMMU_MAX_PT_LEVELS 6
     unsigned int paging_mode:3;
     uint64_t pt_root:40;
     bool ppr:1;
diff --git a/xen/drivers/passthrough/amd/iommu.h 
b/xen/drivers/passthrough/amd/iommu.h
index e4d13f6ef5..b64ef0bf70 100644
--- a/xen/drivers/passthrough/amd/iommu.h
+++ b/xen/drivers/passthrough/amd/iommu.h
@@ -358,7 +358,7 @@ static inline int amd_iommu_get_paging_mode(unsigned long 
max_frames)
     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;
     }
 
diff --git a/xen/drivers/passthrough/amd/iommu_map.c 
b/xen/drivers/passthrough/amd/iommu_map.c
index 8746b00e87..93e4ea2826 100644
--- a/xen/drivers/passthrough/amd/iommu_map.c
+++ b/xen/drivers/passthrough/amd/iommu_map.c
@@ -250,7 +250,7 @@ static int iommu_pde_from_dfn(struct domain *d, unsigned 
long dfn,
     table = hd->arch.amd.root_table;
     level = hd->arch.amd.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
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.15