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It is refactored in two ways: - Make it global so that it could be used in other files. - Make bus/devfn optional so that callers could ignore these two returned values when they only want to get the coresponding iommu pointer. Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> Link: https://lore.kernel.org/r/20200724014925.15523-9-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel <jroedel@suse.de>