Re: [PATCH] AMD IOMMU: don't free page table prematurely

[Andrew Cooper <andrew.cooper3@citrix.com>]

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On 26/05/2014 11:16, Jan Beulich wrote:
> 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>

>
> --- 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:
>
>
>
>
>
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> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel


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