The functions backing the matrix mdev's sysfs attribute interfaces to assign/unassign adapters, domains and control domains must take and release the locks required to perform a dynamic update of a guest's APCB in the proper order. The proper order for taking the locks is: matrix_dev->guests_lock => kvm->lock => matrix_dev->mdevs_lock The proper order for releasing the locks is: matrix_dev->mdevs_lock => kvm->lock => matrix_dev->guests_lock Two new macros are introduced for this purpose: One to take the locks and the other to release the locks. These macros will be used by the assignment/unassignment functions to prepare for dynamic update of the KVM guest's APCB. Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx> --- drivers/s390/crypto/vfio_ap_ops.c | 69 +++++++++++++++++++++++++------ 1 file changed, 57 insertions(+), 12 deletions(-) diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c index 757bbf449b04..2219b1069ceb 100644 --- a/drivers/s390/crypto/vfio_ap_ops.c +++ b/drivers/s390/crypto/vfio_ap_ops.c @@ -71,6 +71,51 @@ static const struct vfio_device_ops vfio_ap_matrix_dev_ops; mutex_unlock(&matrix_dev->guests_lock); \ }) +/** + * get_update_locks_for_mdev: Acquire the locks required to dynamically update a + * KVM guest's APCB in the proper order. + * + * @matrix_mdev: a pointer to a struct ap_matrix_mdev object containing the AP + * configuration data to use to update a KVM 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 guest's APCB + * 3. matrix_dev->mdevs_lock: required to access data stored in a matrix_mdev + * + * Note: If @matrix_mdev is NULL or is not attached to a KVM guest, the KVM + * lock will not be taken. + */ +#define get_update_locks_for_mdev(matrix_mdev) ({ \ + mutex_lock(&matrix_dev->guests_lock); \ + if (matrix_mdev && matrix_mdev->kvm) \ + mutex_lock(&matrix_mdev->kvm->lock); \ + mutex_lock(&matrix_dev->mdevs_lock); \ +}) + +/** + * release_update_locks_for_mdev: Release the locks used to dynamically update a + * KVM guest's APCB in the proper order. + * + * @matrix_mdev: a pointer to a struct ap_matrix_mdev object containing the AP + * configuration data to use to update a KVM guest's APCB. + * + * The proper unlocking order is: + * 1. matrix_dev->mdevs_lock + * 2. matrix_mdev->kvm->lock + * 3. matrix_dev->guests_lock + * + * Note: If @matrix_mdev is NULL or is not attached to a KVM guest, the KVM + * lock will not be released. + */ +#define release_update_locks_for_mdev(matrix_mdev) ({ \ + mutex_unlock(&matrix_dev->mdevs_lock); \ + if (matrix_mdev && matrix_mdev->kvm) \ + mutex_unlock(&matrix_mdev->kvm->lock); \ + mutex_unlock(&matrix_dev->guests_lock); \ +}) + /** * vfio_ap_mdev_get_queue - retrieve a queue with a specific APQN from a * hash table of queues assigned to a matrix mdev @@ -827,7 +872,7 @@ static ssize_t assign_adapter_store(struct device *dev, struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev); - mutex_lock(&matrix_dev->mdevs_lock); + get_update_locks_for_mdev(matrix_mdev); /* If the KVM guest is running, disallow assignment of adapter */ if (matrix_mdev->kvm) { @@ -859,7 +904,7 @@ static ssize_t assign_adapter_store(struct device *dev, matrix_mdev->matrix.aqm, matrix_mdev); ret = count; done: - mutex_unlock(&matrix_dev->mdevs_lock); + release_update_locks_for_mdev(matrix_mdev); return ret; } @@ -902,7 +947,7 @@ static ssize_t unassign_adapter_store(struct device *dev, unsigned long apid; struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev); - mutex_lock(&matrix_dev->mdevs_lock); + get_update_locks_for_mdev(matrix_mdev); /* If the KVM guest is running, disallow unassignment of adapter */ if (matrix_mdev->kvm) { @@ -927,7 +972,7 @@ static ssize_t unassign_adapter_store(struct device *dev, ret = count; done: - mutex_unlock(&matrix_dev->mdevs_lock); + release_update_locks_for_mdev(matrix_mdev); return ret; } static DEVICE_ATTR_WO(unassign_adapter); @@ -982,7 +1027,7 @@ static ssize_t assign_domain_store(struct device *dev, struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev); unsigned long max_apqi = matrix_mdev->matrix.aqm_max; - mutex_lock(&matrix_dev->mdevs_lock); + get_update_locks_for_mdev(matrix_mdev); /* If the KVM guest is running, disallow assignment of domain */ if (matrix_mdev->kvm) { @@ -1013,7 +1058,7 @@ static ssize_t assign_domain_store(struct device *dev, matrix_mdev); ret = count; done: - mutex_unlock(&matrix_dev->mdevs_lock); + release_update_locks_for_mdev(matrix_mdev); return ret; } @@ -1056,7 +1101,7 @@ static ssize_t unassign_domain_store(struct device *dev, unsigned long apqi; struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev); - mutex_lock(&matrix_dev->mdevs_lock); + get_update_locks_for_mdev(matrix_mdev); /* If the KVM guest is running, disallow unassignment of domain */ if (matrix_mdev->kvm) { @@ -1082,7 +1127,7 @@ static ssize_t unassign_domain_store(struct device *dev, ret = count; done: - mutex_unlock(&matrix_dev->mdevs_lock); + release_update_locks_for_mdev(matrix_mdev); return ret; } static DEVICE_ATTR_WO(unassign_domain); @@ -1109,7 +1154,7 @@ static ssize_t assign_control_domain_store(struct device *dev, unsigned long id; struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev); - mutex_lock(&matrix_dev->mdevs_lock); + get_update_locks_for_mdev(matrix_mdev); /* If the KVM guest is running, disallow assignment of control domain */ if (matrix_mdev->kvm) { @@ -1135,7 +1180,7 @@ static ssize_t assign_control_domain_store(struct device *dev, vfio_ap_mdev_filter_cdoms(matrix_mdev); ret = count; done: - mutex_unlock(&matrix_dev->mdevs_lock); + release_update_locks_for_mdev(matrix_mdev); return ret; } static DEVICE_ATTR_WO(assign_control_domain); @@ -1163,7 +1208,7 @@ static ssize_t unassign_control_domain_store(struct device *dev, struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev); unsigned long max_domid = matrix_mdev->matrix.adm_max; - mutex_lock(&matrix_dev->mdevs_lock); + get_update_locks_for_mdev(matrix_mdev); /* If a KVM guest is running, disallow unassignment of control domain */ if (matrix_mdev->kvm) { @@ -1186,7 +1231,7 @@ static ssize_t unassign_control_domain_store(struct device *dev, ret = count; done: - mutex_unlock(&matrix_dev->mdevs_lock); + release_update_locks_for_mdev(matrix_mdev); return ret; } static DEVICE_ATTR_WO(unassign_control_domain); -- 2.31.1