# Commit 6b4d71d028f445cba7426a144751fddc8bfdd67b
# Date 2014-05-28 09:50:33 +0200
# Author Jan Beulich <jbeulich@suse.com>
# Committer Jan Beulich <jbeulich@suse.com>
AMD IOMMU: don't free page table prematurely

iommu_merge_pages() still wants to look at the next level page table,
the TLB flush necessary before freeing too happens in that function,
and if it fails no free should happen at all. Hence the freeing must
be done after that function returned successfully, not before it's
being called.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Tested-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>

--- a/xen/drivers/passthrough/amd/iommu_map.c
+++ b/xen/drivers/passthrough/amd/iommu_map.c
@@ -691,8 +691,6 @@ int amd_iommu_map_page(struct domain *d,
         if ( !iommu_update_pde_count(d, pt_mfn[merge_level],
                                      gfn, mfn, merge_level) )
             break;
-        /* Deallocate lower level page table */
-        free_amd_iommu_pgtable(mfn_to_page(pt_mfn[merge_level - 1]));
 
         if ( iommu_merge_pages(d, pt_mfn[merge_level], gfn, 
                                flags, merge_level) )
@@ -703,6 +701,9 @@ int amd_iommu_map_page(struct domain *d,
             domain_crash(d);
             return -EFAULT;
         }
+
+        /* Deallocate lower level page table */
+        free_amd_iommu_pgtable(mfn_to_page(pt_mfn[merge_level - 1]));
     }
 
 out: