s390/vfio-ap: use proper locking order when setting/clearing KVM pointer

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The group notifier that handles the VFIO_GROUP_NOTIFY_SET_KVM event must
use the required locks in proper locking order to dynamically update the
guest's APCB. The proper locking order is:

       1. matrix_dev->guests_lock: required to use the KVM pointer to
          update a KVM guest's APCB.

       2. matrix_mdev->kvm->lock: required to update a KVM guest's APCB.

       3. matrix_dev->mdevs_lock: required to store or access the data
          stored in a struct ap_matrix_mdev instance.

Two macros are introduced to acquire and release the locks in the proper
order. These macros are now used by the group notifier functions.

Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Jason J. Herne <jjherne@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

...

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Tony Krowiak 2022-03-16 17:46:38 -04:00 • committed by Alexander Gordeev

parent 21195eb038

commit b84eb8e050

1 changed files with 48 additions and 10 deletions

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drivers/s390/crypto/vfio_ap_ops.c

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