drivers/iommu/iommufd/vfio_compat.c:315:17: sparse: sparse: cast removes address space '__user' of expression

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

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   535a265d7f0dd50d8c3a4f8b4f3a452d56bd160f
commit: d624d6652a65ad4f47a58b8651a1ec1163bb81d3 iommufd: vfio container FD ioctl compatibility
date:   9 months ago
config: i386-randconfig-063-20230910 (https://download.01.org/0day-ci/archive/20230910/202309102158.44x6nW0r-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230910/202309102158.44x6nW0r-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202309102158.44x6nW0r-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> drivers/iommu/iommufd/vfio_compat.c:315:17: sparse: sparse: cast removes address space '__user' of expression

vim +/__user +315 drivers/iommu/iommufd/vfio_compat.c

   309	
   310	static int iommufd_fill_cap_iova(struct iommufd_ioas *ioas,
   311					 struct vfio_info_cap_header __user *cur,
   312					 size_t avail)
   313	{
   314		struct vfio_iommu_type1_info_cap_iova_range __user *ucap_iovas =
 > 315			container_of(cur,
   316				     struct vfio_iommu_type1_info_cap_iova_range __user,
   317				     header);
   318		struct vfio_iommu_type1_info_cap_iova_range cap_iovas = {
   319			.header = {
   320				.id = VFIO_IOMMU_TYPE1_INFO_CAP_IOVA_RANGE,
   321				.version = 1,
   322			},
   323		};
   324		struct interval_tree_span_iter span;
   325	
   326		interval_tree_for_each_span(&span, &ioas->iopt.reserved_itree, 0,
   327					    ULONG_MAX) {
   328			struct vfio_iova_range range;
   329	
   330			if (!span.is_hole)
   331				continue;
   332			range.start = span.start_hole;
   333			range.end = span.last_hole;
   334			if (avail >= struct_size(&cap_iovas, iova_ranges,
   335						 cap_iovas.nr_iovas + 1) &&
   336			    copy_to_user(&ucap_iovas->iova_ranges[cap_iovas.nr_iovas],
   337					 &range, sizeof(range)))
   338				return -EFAULT;
   339			cap_iovas.nr_iovas++;
   340		}
   341		if (avail >= struct_size(&cap_iovas, iova_ranges, cap_iovas.nr_iovas) &&
   342		    copy_to_user(ucap_iovas, &cap_iovas, sizeof(cap_iovas)))
   343			return -EFAULT;
   344		return struct_size(&cap_iovas, iova_ranges, cap_iovas.nr_iovas);
   345	}
   346	

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