Hi Peter,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on vhost/linux-next]
[also build test WARNING on linus/master v5.7-rc7]
[cannot apply to kvm/linux-next tip/auto-latest linux/master next-20200526]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Peter-Xu/KVM-Dirty-ring-interface/20200524-070926
base:   https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git linux-next
config: x86_64-allyesconfig (attached as .config)
compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project 3393cc4cebf9969db94dc424b7a2b6195589c33b)
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: kbuild test robot <lkp@intel.com>

All warnings (new ones prefixed by >>, old ones prefixed by <<):

>> arch/x86/kvm/mmu/mmu.c:1280:10: warning: expression which evaluates to zero treated as a null pointer constant of type 'struct kvm_memory_slot *' [-Wnon-literal-null-conversion]
return false;
^~~~~
1 warning generated.

vim +1280 arch/x86/kvm/mmu/mmu.c

  1269	
  1270	static struct kvm_memory_slot *
  1271	gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t gfn,
  1272				    bool no_dirty_log)
  1273	{
  1274		struct kvm_memory_slot *slot;
  1275	
  1276		slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
  1277		if (!slot || slot->flags & KVM_MEMSLOT_INVALID)
  1278			return NULL;
  1279		if (no_dirty_log && kvm_slot_dirty_track_enabled(slot))
> 1280			return false;
  1281	
  1282		return slot;
  1283	}
  1284	

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