[luxis1999-iommufd:iommufd-v5.17-rc6 37/40] undefined reference to `iommufd_vfio_check_extension'

[kernel test robot <lkp@intel.com>]

tree:   https://github.com/luxis1999/iommufd iommufd-v5.17-rc6
head:   cde3fc107eb3877b1055b6c5cd048c18d6f5b8d5
commit: a3f133279ae994c62f5a14dbcd334564651484c8 [37/40] vfio: Add iommufd VFIO compat support to group_fd
config: microblaze-randconfig-m031-20220308 (https://download.01.org/0day-ci/archive/20220309/202203091936.QAP99zL8-lkp@intel.com/config)
compiler: microblaze-linux-gcc (GCC) 11.2.0
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/luxis1999/iommufd/commit/a3f133279ae994c62f5a14dbcd334564651484c8
        git remote add luxis1999-iommufd https://github.com/luxis1999/iommufd
        git fetch --no-tags luxis1999-iommufd iommufd-v5.17-rc6
        git checkout a3f133279ae994c62f5a14dbcd334564651484c8
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=microblaze SHELL=/bin/bash

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

All errors (new ones prefixed by >>):

   microblaze-linux-ld: drivers/vfio/vfio.o: in function `vfio_external_check_extension':
>> (.text+0x14dc): undefined reference to `iommufd_vfio_check_extension'
   microblaze-linux-ld: drivers/vfio/vfio.o: in function `__vfio_group_unset_container':
>> (.text+0x1554): undefined reference to `vfio_group_unset_iommufd'
   microblaze-linux-ld: drivers/vfio/vfio.o: in function `vfio_group_set_container':
>> (.text+0x1d50): undefined reference to `vfio_group_set_iommufd'

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0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org