Re: drivers/vfio/vfio_iommu_type1.c:2147:35: warning: cast to smaller integer type 'enum iommu_cap' from 'void *'

From: Jason Gunthorpe
Date: Fri Aug 12 2022 - 10:12:40 EST


On Wed, Aug 10, 2022 at 11:25:15AM +0800, kernel test robot wrote:
> Hi Robin,
>
> FYI, the error/warning still remains.
>
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head: d4252071b97d2027d246f6a82cbee4d52f618b47
> commit: eed20c782aea57b7efb42af2905dc381268b21e9 vfio/type1: Simplify bus_type determination
> date: 6 weeks ago
> config: arm64-randconfig-r034-20220810 (https://download.01.org/0day-ci/archive/20220810/202208101119.7unZx9dJ-lkp@xxxxxxxxx/config)
> compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 5f1c7e2cc5a3c07cbc2412e851a7283c1841f520)
> 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 arm64 cross compiling tool for clang build
> # apt-get install binutils-aarch64-linux-gnu
> # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=eed20c782aea57b7efb42af2905dc381268b21e9
> git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> git fetch --no-tags linus master
> git checkout eed20c782aea57b7efb42af2905dc381268b21e9
> # save the config file
> mkdir build_dir && cp config build_dir/.config
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm64 SHELL=/bin/bash drivers/vfio/
>
> If you fix the issue, kindly add following tag where applicable
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
>
> All warnings (new ones prefixed by >>):
>
> >> drivers/vfio/vfio_iommu_type1.c:2147:35: warning: cast to smaller integer type 'enum iommu_cap' from 'void *' [-Wvoid-pointer-to-enum-cast]
> return device_iommu_capable(dev, (enum iommu_cap)data);
> ^~~~~~~~~~~~~~~~~~~~
> 1 warning generated.
>
>
> vim +2147 drivers/vfio/vfio_iommu_type1.c
>
> 2143
> 2144 /* Redundantly walks non-present capabilities to simplify caller */
> 2145 static int vfio_iommu_device_capable(struct device *dev, void *data)
> 2146 {
> > 2147 return device_iommu_capable(dev, (enum iommu_cap)data);

This wants to be written as

return device_iommu_capable(dev, (uintptr_t)data);

Jason