Hi Xin,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on ipsec-next/master]

url:    https://github.com/0day-ci/linux/commits/Xin-Long/xfrm-support-ipip-and-ipv6-tunnels-in-vti-and-xfrmi/20200630-154042
base:   https://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next.git master
config: h8300-randconfig-r001-20200701 (attached as .config)
compiler: h8300-linux-gcc (GCC) 9.3.0
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
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=h8300 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <redacted>

All errors (new ones prefixed by >>):

   h8300-linux-ld: net/ipv4/tunnel4.o: in function `tunnel4_init':
   net/ipv4/tunnel4.c:242: undefined reference to `xfrm_input_register_afinfo'

quoted

h8300-linux-ld: net/ipv4/tunnel4.c:245: undefined reference to `xfrm_input_unregister_afinfo'

   h8300-linux-ld: net/ipv4/tunnel4.c:250: undefined reference to `xfrm_input_unregister_afinfo'

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