linux-kernel - Re: drivers/vfio/vfio_iommu_type1.c:2147:35: warning: cast to smaller integer type 'enum iommu

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Message-ID: <YvZfz9z/TGzuzvDQ@nvidia.com>
Date:   Fri, 12 Aug 2022 11:12:31 -0300
From:   Jason Gunthorpe <jgg@...dia.com>
To:     kernel test robot <lkp@...el.com>
Cc:     Robin Murphy <robin.murphy@....com>, llvm@...ts.linux.dev,
        kbuild-all@...ts.01.org, linux-kernel@...r.kernel.org,
        Alex Williamson <alex.williamson@...hat.com>,
        Kevin Tian <kevin.tian@...el.com>
Subject: Re: drivers/vfio/vfio_iommu_type1.c:2147:35: warning: cast to
 smaller integer type 'enum iommu_cap' from 'void *'

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@intel.com/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@...el.com>
> 
> 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