s390/vfio-ap: reset queues filtered from the guest's AP config

When filtering the adapters from the configuration profile for a guest to
create or update a guest's AP configuration, if the APID of an adapter and
the APQI of a domain identify a queue device that is not bound to the
vfio_ap device driver, the APID of the adapter will be filtered because an
individual APQN can not be filtered due to the fact the APQNs are assigned
to an AP configuration as a matrix of APIDs and APQIs. Consequently, a
guest will not have access to all of the queues associated with the
filtered adapter. If the queues are subsequently made available again to
the guest, they should re-appear in a reset state; so, let's make sure all
queues associated with an adapter unplugged from the guest are reset.

In order to identify the set of queues that need to be reset, let's allow a
vfio_ap_queue object to be simultaneously stored in both a hashtable and a
list: A hashtable used to store all of the queues assigned
to a matrix mdev; and/or, a list used to store a subset of the queues that
need to be reset. For example, when an adapter is hot unplugged from a
guest, all guest queues associated with that adapter must be reset. Since
that may be a subset of those assigned to the matrix mdev, they can be
stored in a list that can be passed to the vfio_ap_mdev_reset_queues
function.
Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Acked-by: Halil Pasic <pasic@linux.ibm.com>
Fixes: 48cae940 ("s390/vfio-ap: refresh guest's APCB by filtering AP resources assigned to mdev")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240115185441.31526-5-akrowiak@linux.ibm.comSigned-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

drivers/s390/crypto/vfio_ap_private.h

@@ -133,6 +133,8 @@ struct ap_matrix_mdev {
  * @apqn: the APQN of the AP queue device
  * @saved_isc: the guest ISC registered with the GIB interface
  * @mdev_qnode: allows the vfio_ap_queue struct to be added to a hashtable
+ * @reset_qnode: allows the vfio_ap_queue struct to be added to a list of queues
+ *		 that need to be reset
  * @reset_status: the status from the last reset of the queue
  * @reset_work: work to wait for queue reset to complete
  */
@@ -143,6 +145,7 @@ struct vfio_ap_queue {
 #define VFIO_AP_ISC_INVALID 0xff
 	unsigned char saved_isc;
 	struct hlist_node mdev_qnode;
+	struct list_head reset_qnode;
 	struct ap_queue_status reset_status;
 	struct work_struct reset_work;
 };