Re: [PATCH v1 1/3] Add map/unmap ioctl and clean mappings post-guest

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

Hi Douglas,

kernel test robot noticed the following build warnings:

[auto build test WARNING on v7.0-rc2]
[also build test WARNING on linus/master next-20260306]
[cannot apply to kvms390/next]
[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#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Douglas-Freimuth/Add-map-unmap-ioctl-and-clean-mappings-post-guest/20260308-110653
base:   v7.0-rc2
patch link:    https://lore.kernel.org/r/20260308030438.88580-2-freimuth%40linux.ibm.com
patch subject: [PATCH v1 1/3] Add map/unmap ioctl and clean mappings post-guest
config: s390-allmodconfig (https://download.01.org/0day-ci/archive/20260308/202603082108.iY5mWhWR-lkp@intel.com/config)
compiler: clang version 18.1.8 (https://github.com/llvm/llvm-project 3b5b5c1ec4a3095ab096dd780e84d7ab81f3d7ff)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260308/202603082108.iY5mWhWR-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/202603082108.iY5mWhWR-lkp@intel.com/

All warnings (new ones prefixed by >>):

   arch/s390/kvm/interrupt.c:2478:16: warning: unused variable 'flags' [-Wunused-variable]
    2478 |         unsigned long flags;
         |                       ^~~~~
>> arch/s390/kvm/interrupt.c:2578:7: warning: variable 'ret' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
    2578 |                 if (kvm_s390_pv_is_protected(dev->kvm)) {
         |                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   arch/s390/kvm/interrupt.c:2602:9: note: uninitialized use occurs here
    2602 |         return ret;
         |                ^~~
   arch/s390/kvm/interrupt.c:2578:3: note: remove the 'if' if its condition is always false
    2578 |                 if (kvm_s390_pv_is_protected(dev->kvm)) {
         |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    2579 |                         mutex_unlock(&dev->kvm->lock);
         |                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    2580 |                         break;
         |                         ~~~~~~
    2581 |                 }
         |                 ~
   arch/s390/kvm/interrupt.c:2561:9: note: initialize the variable 'ret' to silence this warning
    2561 |         int ret, idx;
         |                ^
         |                 = 0
   2 warnings generated.


vim +2578 arch/s390/kvm/interrupt.c

  2554	
  2555	static int modify_io_adapter(struct kvm_device *dev,
  2556				     struct kvm_device_attr *attr)
  2557	{
  2558		struct kvm_s390_io_adapter_req req;
  2559		struct s390_io_adapter *adapter;
  2560		__u64 host_addr;
  2561		int ret, idx;
  2562	
  2563		if (copy_from_user(&req, (void __user *)attr->addr, sizeof(req)))
  2564			return -EFAULT;
  2565	
  2566		adapter = get_io_adapter(dev->kvm, req.id);
  2567		if (!adapter)
  2568			return -EINVAL;
  2569		switch (req.type) {
  2570		case KVM_S390_IO_ADAPTER_MASK:
  2571			ret = kvm_s390_mask_adapter(dev->kvm, req.id, req.mask);
  2572			if (ret > 0)
  2573				ret = 0;
  2574			break;
  2575		case KVM_S390_IO_ADAPTER_MAP:
  2576		case KVM_S390_IO_ADAPTER_UNMAP:
  2577			mutex_lock(&dev->kvm->lock);
> 2578			if (kvm_s390_pv_is_protected(dev->kvm)) {
  2579				mutex_unlock(&dev->kvm->lock);
  2580				break;
  2581			}
  2582			mutex_unlock(&dev->kvm->lock);
  2583			idx = srcu_read_lock(&dev->kvm->srcu);
  2584			host_addr = gpa_to_hva(dev->kvm, req.addr);
  2585			if (kvm_is_error_hva(host_addr)) {
  2586				srcu_read_unlock(&dev->kvm->srcu, idx);
  2587				return -EFAULT;
  2588				}
  2589			srcu_read_unlock(&dev->kvm->srcu, idx);
  2590			if (req.type == KVM_S390_IO_ADAPTER_MAP) {
  2591				dev->kvm->stat.io_390_adapter_map++;
  2592				ret = kvm_s390_adapter_map(dev->kvm, req.id, host_addr);
  2593			} else {
  2594				dev->kvm->stat.io_390_adapter_unmap++;
  2595				ret = kvm_s390_adapter_unmap(dev->kvm, req.id, host_addr);
  2596			}
  2597			break;
  2598		default:
  2599			ret = -EINVAL;
  2600		}
  2601	
  2602		return ret;
  2603	}
  2604	

-- 
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https://github.com/intel/lkp-tests/wiki