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

[Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>]

On 05/26/2014 05:16 AM, 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>
>
> --- 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:
>
>
>

Reviewed and tested. By the way, is this patch fix any existing known 
issues?

Suravee