Hi Jason,

I love your patch! Perhaps something to improve:

[auto build test WARNING on vhost/linux-next]
[also build test WARNING on linus/master v5.9-rc1 next-20200821]
[cannot apply to linux/master]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Jason-Wang/vDPA-API-for-reporting-IOVA-range/20200821-173030
base:   https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git linux-next
config: x86_64-randconfig-a002-20200820 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project b587ca93be114d07ec3bf654add97d7872325281)
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
        # install x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

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

All warnings (new ones prefixed by >>):

>> drivers/vdpa/vdpa_sim/vdpa_sim.c:577:24: warning: no previous prototype for function 'vdpasim_get_iova_range' [-Wmissing-prototypes]
   struct vdpa_iova_range vdpasim_get_iova_range(struct vdpa_device *vdpa)
                          ^
   drivers/vdpa/vdpa_sim/vdpa_sim.c:577:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   struct vdpa_iova_range vdpasim_get_iova_range(struct vdpa_device *vdpa)
   ^
   static 
   drivers/vdpa/vdpa_sim/vdpa_sim.c:89:19: warning: unused function 'vdpasim16_to_cpu' [-Wunused-function]
   static inline u16 vdpasim16_to_cpu(struct vdpasim *vdpasim, __virtio16 val)
                     ^
   2 warnings generated.

# https://github.com/0day-ci/linux/commit/fba5ff6281e9d46144860bcc558068b5516e5e62
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Jason-Wang/vDPA-API-for-reporting-IOVA-range/20200821-173030
git checkout fba5ff6281e9d46144860bcc558068b5516e5e62
vim +/vdpasim_get_iova_range +577 drivers/vdpa/vdpa_sim/vdpa_sim.c

   576	
 > 577	struct vdpa_iova_range vdpasim_get_iova_range(struct vdpa_device *vdpa)
   578	{
   579		struct vdpa_iova_range range = {
   580			.first = 0ULL,
   581			.last = ULLONG_MAX,
   582		};
   583	
   584		return range;
   585	}
   586	

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