drivers/s390/crypto/vfio_ap_ops.c:2885:0-1: preceding lock on line 2865

drivers/s390/crypto/vfio_ap_ops.c:2885:0-1: preceding lock on line 2865

[kernel test robot]

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
CC: linux-kernel@vger.kernel.org
TO: Anthony Krowiak <akrowiak@linux.ibm.com>
CC: Christian Borntraeger <borntraeger@linux.ibm.com>
CC: Matthew Rosato <mjrosato@linux.ibm.com>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   e767a4ea70a3992c37ed604157d32f0dfbf9b1e3
commit: d50346801b4f144e42b49cd4f1496010498ab114 s390/vfio-ap: Fix dereference matrix_mdev->kvm without checking for NULL
date:   7 weeks ago
:::::: branch date: 9 hours ago
:::::: commit date: 7 weeks ago
config: s390-randconfig-r2105-20261002 (https://download.01.org/0day-ci/archive/20261003/202610031130.UN60GSBb-lkp@intel.com/config)
compiler: clang version 24.0.0git (https://github.com/llvm/llvm-project d7e4505dd447d115d85fdea45cd71030ac1d86ee)
rustc: rustc 1.96.0 (ac68faa20 2026-05-25)

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
| Fixes: d50346801b4f ("s390/vfio-ap: Fix dereference matrix_mdev->kvm without checking for NULL")
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Julia Lawall <julia.lawall@inria.fr>
| Closes: https://lore.kernel.org/r/202610031130.UN60GSBb-lkp@intel.com/

cocci warnings: (new ones prefixed by >>)
>> drivers/s390/crypto/vfio_ap_ops.c:2885:0-1: preceding lock on line 2865

vim +2885 drivers/s390/crypto/vfio_ap_ops.c

eeb386aeb5b7c8 Tony Krowiak    2022-04-04  2850  
eeb386aeb5b7c8 Tony Krowiak    2022-04-04  2851  void vfio_ap_on_scan_complete(struct ap_config_info *new_config_info,
eeb386aeb5b7c8 Tony Krowiak    2022-04-04  2852  			      struct ap_config_info *old_config_info)
eeb386aeb5b7c8 Tony Krowiak    2022-04-04  2853  {
eeb386aeb5b7c8 Tony Krowiak    2022-04-04  2854  	struct ap_matrix_mdev *matrix_mdev;
eeb386aeb5b7c8 Tony Krowiak    2022-04-04  2855  
eeb386aeb5b7c8 Tony Krowiak    2022-04-04  2856  	mutex_lock(&matrix_dev->guests_lock);
eeb386aeb5b7c8 Tony Krowiak    2022-04-04  2857  
eeb386aeb5b7c8 Tony Krowiak    2022-04-04  2858  	list_for_each_entry(matrix_mdev, &matrix_dev->mdev_list, node) {
d50346801b4f14 Anthony Krowiak 2026-08-12  2859  		/*
d50346801b4f14 Anthony Krowiak 2026-08-12  2860  		 * The mdevs_lock must be held to access fields within matrix_mdev,
d50346801b4f14 Anthony Krowiak 2026-08-12  2861  		 * and kvm->lock must be taken before mdevs_lock to satisfy the lock
d50346801b4f14 Anthony Krowiak 2026-08-12  2862  		 * ordering requirement and prevent a lockdep splat.
d50346801b4f14 Anthony Krowiak 2026-08-12  2863  		 */
d50346801b4f14 Anthony Krowiak 2026-08-12  2864  		if (matrix_mdev->kvm)
d50346801b4f14 Anthony Krowiak 2026-08-12 @2865  			mutex_lock(&matrix_mdev->kvm->lock);
d50346801b4f14 Anthony Krowiak 2026-08-12  2866  		mutex_lock(&matrix_dev->mdevs_lock);
d50346801b4f14 Anthony Krowiak 2026-08-12  2867  
eeb386aeb5b7c8 Tony Krowiak    2022-04-04  2868  		if (bitmap_empty(matrix_mdev->apm_add, AP_DEVICES) &&
eeb386aeb5b7c8 Tony Krowiak    2022-04-04  2869  		    bitmap_empty(matrix_mdev->aqm_add, AP_DOMAINS) &&
eeb386aeb5b7c8 Tony Krowiak    2022-04-04  2870  		    bitmap_empty(matrix_mdev->adm_add, AP_DOMAINS))
d50346801b4f14 Anthony Krowiak 2026-08-12  2871  			goto do_unlock;
eeb386aeb5b7c8 Tony Krowiak    2022-04-04  2872  
eeb386aeb5b7c8 Tony Krowiak    2022-04-04  2873  		vfio_ap_mdev_hot_plug_cfg(matrix_mdev);
eeb386aeb5b7c8 Tony Krowiak    2022-04-04  2874  		bitmap_clear(matrix_mdev->apm_add, 0, AP_DEVICES);
eeb386aeb5b7c8 Tony Krowiak    2022-04-04  2875  		bitmap_clear(matrix_mdev->aqm_add, 0, AP_DOMAINS);
eeb386aeb5b7c8 Tony Krowiak    2022-04-04  2876  		bitmap_clear(matrix_mdev->adm_add, 0, AP_DOMAINS);
d50346801b4f14 Anthony Krowiak 2026-08-12  2877  
d50346801b4f14 Anthony Krowiak 2026-08-12  2878  do_unlock:
d50346801b4f14 Anthony Krowiak 2026-08-12  2879  		mutex_unlock(&matrix_dev->mdevs_lock);
d50346801b4f14 Anthony Krowiak 2026-08-12  2880  		if (matrix_mdev->kvm)
d50346801b4f14 Anthony Krowiak 2026-08-12  2881  			mutex_unlock(&matrix_mdev->kvm->lock);
eeb386aeb5b7c8 Tony Krowiak    2022-04-04  2882  	}
eeb386aeb5b7c8 Tony Krowiak    2022-04-04  2883  
eeb386aeb5b7c8 Tony Krowiak    2022-04-04  2884  	mutex_unlock(&matrix_dev->guests_lock);
eeb386aeb5b7c8 Tony Krowiak    2022-04-04 @2885  }

:::::: The code at line 2885 was first introduced by commit
:::::: eeb386aeb5b7c8d2dae6a3ba49255d8a97803182 s390/vfio-ap: handle config changed and scan complete notification

:::::: TO: Tony Krowiak <akrowiak@linux.ibm.com>
:::::: CC: Alexander Gordeev <agordeev@linux.ibm.com>

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