tree:   https://github.com/jgunthorpe/linux vfio_iommufd
head:   f44b706a4413f17e50f20999964b38d11ef84d98
commit: 7bdc8312d65ca5d0f189c073ab1d5a48a2a7bfbc [1/20] iommufd: PFN handling for iopt_pages
config: s390-allmodconfig
compiler: s390-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/jgunthorpe/linux/commit/7bdc8312d65ca5d0f189c073ab1d5a48a2a7bfbc
        git remote add jgunthorpe https://github.com/jgunthorpe/linux
        git fetch --no-tags jgunthorpe vfio_iommufd
        git checkout 7bdc8312d65ca5d0f189c073ab1d5a48a2a7bfbc
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=s390 SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> drivers/iommu/iommufd/pages.c:275:5: warning: no previous prototype for 'batch_iommu_map_small' [-Wmissing-prototypes]
     275 | int batch_iommu_map_small(struct iommu_domain *domain, unsigned long iova,
         |     ^~~~~~~~~~~~~~~~~~~~~
   drivers/iommu/iommufd/pages.c:816:12: warning: 'pfn_reader_first' defined but not used [-Wunused-function]
     816 | static int pfn_reader_first(struct pfn_reader *pfns, struct iopt_pages *pages,
         |            ^~~~~~~~~~~~~~~~
   drivers/iommu/iommufd/pages.c:750:12: warning: 'pfn_reader_seek_hole' defined but not used [-Wunused-function]
     750 | static int pfn_reader_seek_hole(struct pfn_reader *pfns,
         |            ^~~~~~~~~~~~~~~~~~~~
   drivers/iommu/iommufd/pages.c:722:13: warning: 'pfn_reader_done' defined but not used [-Wunused-function]
     722 | static bool pfn_reader_done(struct pfn_reader *pfns)
         |             ^~~~~~~~~~~~~~~
   drivers/iommu/iommufd/pages.c:553:12: warning: 'update_pinned' defined but not used [-Wunused-function]
     553 | static int update_pinned(struct iopt_pages *pages)
         |            ^~~~~~~~~~~~~
   drivers/iommu/iommufd/pages.c:474:22: warning: 'batch_rw' defined but not used [-Wunused-function]
     474 | static unsigned long batch_rw(struct pfn_batch *batch, void *data,
         |                      ^~~~~~~~
   drivers/iommu/iommufd/pages.c:408:13: warning: 'batch_to_pages' defined but not used [-Wunused-function]
     408 | static void batch_to_pages(struct pfn_batch *batch, struct page **pages)
         |             ^~~~~~~~~~~~~~
   drivers/iommu/iommufd/pages.c:373:12: warning: 'batch_to_xarray' defined but not used [-Wunused-function]
     373 | static int batch_to_xarray(struct pfn_batch *batch, struct xarray *xa,
         |            ^~~~~~~~~~~~~~~
   drivers/iommu/iommufd/pages.c:297:12: warning: 'batch_to_domain' defined but not used [-Wunused-function]
     297 | static int batch_to_domain(struct pfn_batch *batch, struct iommu_domain *domain,
         |            ^~~~~~~~~~~~~~~
   drivers/iommu/iommufd/pages.c:203:13: warning: 'batch_init_backup' defined but not used [-Wunused-function]
     203 | static void batch_init_backup(struct pfn_batch *batch, size_t max_pages,
         |             ^~~~~~~~~~~~~~~~~
   drivers/iommu/iommufd/pages.c:121:22: warning: 'iopt_area_index_to_iova_last' defined but not used [-Wunused-function]
     121 | static unsigned long iopt_area_index_to_iova_last(struct iopt_area *area,
         |                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~


vim +/batch_iommu_map_small +275 drivers/iommu/iommufd/pages.c

   267	
   268	/*
   269	 * This is part of the VFIO compatability support for VFIO_TYPE1_IOMMU. That
   270	 * mode permits splitting a mapped area up, and then one of the splits is
   271	 * unmapped. Doing this normally would cause us to violate our invariant of
   272	 * pairing map/unmap. Thus, to support old VFIO compatability disable support
   273	 * for batching consecutive PFNs.
   274	 */
 > 275	int batch_iommu_map_small(struct iommu_domain *domain, unsigned long iova,
   276				  phys_addr_t paddr, size_t size, int prot)
   277	{
   278		unsigned long start_iova = iova;
   279		int rc;
   280	
   281		while (size) {
   282			rc = iommu_map(domain, iova, paddr, PAGE_SIZE, prot);
   283			if (rc)
   284				goto err_unmap;
   285			iova += PAGE_SIZE;
   286			paddr += PAGE_SIZE;
   287			size -= PAGE_SIZE;
   288		}
   289		return 0;
   290	
   291	err_unmap:
   292		if (start_iova != iova)
   293			iommu_unmap_nofail(domain, start_iova, iova - start_iova);
   294		return rc;
   295	}
   296	

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