Re: [PATCH 2/4] KVM: VFIO: use mutex guard in kvm_vfio_file_set_spapr_tce()

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

Hi Carlos,

kernel test robot noticed the following build warnings:

[auto build test WARNING on d2ea4ff1ce50787a98a3900b3fb1636f3620b7cf]

url:    https://github.com/intel-lab-lkp/linux/commits/Carlos-L-pez/KVM-VFIO-clean-up-control-flow-in-kvm_vfio_file_add/20260314-053050
base:   d2ea4ff1ce50787a98a3900b3fb1636f3620b7cf
patch link:    https://lore.kernel.org/r/20260313122040.1413091-5-clopez%40suse.de
patch subject: [PATCH 2/4] KVM: VFIO: use mutex guard in kvm_vfio_file_set_spapr_tce()
config: powerpc-allmodconfig (https://download.01.org/0day-ci/archive/20260403/202604031640.vckbuS2S-lkp@intel.com/config)
compiler: powerpc64-linux-gcc (GCC) 15.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260403/202604031640.vckbuS2S-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/202604031640.vckbuS2S-lkp@intel.com/

All warnings (new ones prefixed by >>):

   arch/powerpc/kvm/../../../virt/kvm/vfio.c: In function 'kvm_vfio_file_set_spapr_tce':
>> arch/powerpc/kvm/../../../virt/kvm/vfio.c:219:13: warning: unused variable 'ret' [-Wunused-variable]
     219 |         int ret;
         |             ^~~


vim +/ret +219 arch/powerpc/kvm/../../../virt/kvm/vfio.c

121f80ba68f1a57 Alexey Kardashevskiy 2017-03-22  211  
121f80ba68f1a57 Alexey Kardashevskiy 2017-03-22  212  #ifdef CONFIG_SPAPR_TCE_IOMMU
2f99073a722beef Yi Liu               2023-07-18  213  static int kvm_vfio_file_set_spapr_tce(struct kvm_device *dev,
73b0565f19a8fbc Jason Gunthorpe      2022-05-04  214  				       void __user *arg)
73b0565f19a8fbc Jason Gunthorpe      2022-05-04  215  {
121f80ba68f1a57 Alexey Kardashevskiy 2017-03-22  216  	struct kvm_vfio_spapr_tce param;
121f80ba68f1a57 Alexey Kardashevskiy 2017-03-22  217  	struct kvm_vfio *kv = dev->private;
2f99073a722beef Yi Liu               2023-07-18  218  	struct kvm_vfio_file *kvf;
73b0565f19a8fbc Jason Gunthorpe      2022-05-04 @219  	int ret;
121f80ba68f1a57 Alexey Kardashevskiy 2017-03-22  220  
73b0565f19a8fbc Jason Gunthorpe      2022-05-04  221  	if (copy_from_user(&param, arg, sizeof(struct kvm_vfio_spapr_tce)))
121f80ba68f1a57 Alexey Kardashevskiy 2017-03-22  222  		return -EFAULT;
121f80ba68f1a57 Alexey Kardashevskiy 2017-03-22  223  
8152f8201088350 Al Viro              2024-07-19  224  	CLASS(fd, f)(param.groupfd);
8152f8201088350 Al Viro              2024-07-19  225  	if (fd_empty(f))
121f80ba68f1a57 Alexey Kardashevskiy 2017-03-22  226  		return -EBADF;
121f80ba68f1a57 Alexey Kardashevskiy 2017-03-22  227  
db3d8c11676213b Carlos López         2026-03-13  228  	guard(mutex)(&kv->lock);
121f80ba68f1a57 Alexey Kardashevskiy 2017-03-22  229  
2f99073a722beef Yi Liu               2023-07-18  230  	list_for_each_entry(kvf, &kv->file_list, node) {
1da91ea87aefe2c Al Viro              2024-05-31  231  		if (kvf->file != fd_file(f))
121f80ba68f1a57 Alexey Kardashevskiy 2017-03-22  232  			continue;
121f80ba68f1a57 Alexey Kardashevskiy 2017-03-22  233  
2f99073a722beef Yi Liu               2023-07-18  234  		if (!kvf->iommu_group) {
2f99073a722beef Yi Liu               2023-07-18  235  			kvf->iommu_group = kvm_vfio_file_iommu_group(kvf->file);
db3d8c11676213b Carlos López         2026-03-13  236  			if (WARN_ON_ONCE(!kvf->iommu_group))
db3d8c11676213b Carlos López         2026-03-13  237  				return -EIO;
819da99a7360f7e Jason Gunthorpe      2022-10-07  238  		}
d55d9e7a4572182 Jason Gunthorpe      2022-05-04  239  
db3d8c11676213b Carlos López         2026-03-13  240  		return kvm_spapr_tce_attach_iommu_group(dev->kvm, param.tablefd,
2f99073a722beef Yi Liu               2023-07-18  241  							kvf->iommu_group);
121f80ba68f1a57 Alexey Kardashevskiy 2017-03-22  242  	}
121f80ba68f1a57 Alexey Kardashevskiy 2017-03-22  243  
db3d8c11676213b Carlos López         2026-03-13  244  	return -ENOENT;
121f80ba68f1a57 Alexey Kardashevskiy 2017-03-22  245  }
73b0565f19a8fbc Jason Gunthorpe      2022-05-04  246  #endif
73b0565f19a8fbc Jason Gunthorpe      2022-05-04  247  

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