Hi Steve,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on vfio/next]
[also build test WARNING on v5.11-rc2 next-20210104]
[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/Steve-Sistare/vfio-virtual-address-update/20210106-000752
base:   https://github.com/awilliam/linux-vfio.git next
config: x86_64-randconfig-s022-20210105 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.3-208-g46a52ca4-dirty
        # https://github.com/0day-ci/linux/commit/c7f4454de15f02ea6be7591e8ab4520e21da646e
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Steve-Sistare/vfio-virtual-address-update/20210106-000752
        git checkout c7f4454de15f02ea6be7591e8ab4520e21da646e
        # save the attached .config to linux build tree
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=x86_64 

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


"sparse warnings: (new ones prefixed by >>)"
>> drivers/vfio/vfio_iommu_type1.c:160:32: sparse: sparse: Using plain integer as NULL pointer
   drivers/vfio/vfio_iommu_type1.c:176:23: sparse: sparse: Using plain integer as NULL pointer

vim +160 drivers/vfio/vfio_iommu_type1.c

   147	
   148	static struct vfio_group *vfio_iommu_find_iommu_group(struct vfio_iommu *iommu,
   149						       struct iommu_group *iommu_group);
   150	
   151	static void update_pinned_page_dirty_scope(struct vfio_iommu *iommu);
   152	/*
   153	 * This code handles mapping and unmapping of user data buffers
   154	 * into DMA'ble space using the IOMMU
   155	 */
   156	
   157	static struct vfio_dma *vfio_find_dma(struct vfio_iommu *iommu,
   158					      dma_addr_t start, size_t size)
   159	{
 > 160		struct vfio_dma *res = 0;
   161		struct rb_node *node = iommu->dma_list.rb_node;
   162	
   163		while (node) {
   164			struct vfio_dma *dma = rb_entry(node, struct vfio_dma, node);
   165	
   166			if (start < dma->iova + dma->size) {
   167				res = dma;
   168				if (start >= dma->iova)
   169					break;
   170				node = node->rb_left;
   171			} else {
   172				node = node->rb_right;
   173			}
   174		}
   175		if (res && size && res->iova >= start + size)
   176			res = 0;
   177		return res;
   178	}
   179	

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