[PATCH v14 12/13] s390/zcrypt: notify drivers on config changed and scan complete callbacks

[Tony Krowiak]

This patch intruduces an extension to the ap bus to notify device drivers
when the host AP configuration changes - i.e., adapters, domains or
control domains are added or removed. To that end, two new callbacks are
introduced for AP device drivers:

  void (*on_config_changed)(struct ap_config_info *new_config_info,
                            struct ap_config_info *old_config_info);

     This callback is invoked at the start of the AP bus scan
     function when it determines that the host AP configuration information
     has changed since the previous scan. This is done by storing
     an old and current QCI info struct and comparing them. If there is any
     difference, the callback is invoked.

     Note that when the AP bus scan detects that AP adapters, domains or
     control domains have been removed from the host's AP configuration, it
     will remove the associated devices from the AP bus subsystem's device
     model. This callback gives the device driver a chance to respond to
     the removal of the AP devices from the host configuration prior to
     calling the device driver's remove callback. The primary purpose of
     this callback is to allow the vfio_ap driver to do a bulk unplug of
     all affected adapters, domains and control domains from affected
     guests rather than unplugging them one at a time when the remove
     callback is invoked.

  void (*on_scan_complete)(struct ap_config_info *new_config_info,
                           struct ap_config_info *old_config_info);

     The on_scan_complete callback is invoked after the ap bus scan is
     complete if the host AP configuration data has changed.

     Note that when the AP bus scan detects that adapters, domains or
     control domains have been added to the host's configuration, it will
     create new devices in the AP bus subsystem's device model. The primary
     purpose of this callback is to allow the vfio_ap driver to do a bulk
     plug of all affected adapters, domains and control domains into
     affected guests rather than plugging them one at a time when the
     probe callback is invoked.

Please note that changes to the apmask and aqmask do not trigger
these two callbacks since the bus scan function is not invoked by changes
to those masks.

Signed-off-by: Harald Freudenberger <freude@xxxxxxxxxxxxx>
Reviewed-by: Halil Pasic <pasic@xxxxxxxxxxxxx>
Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
---
 drivers/s390/crypto/ap_bus.c          |  89 ++++++++++-
 drivers/s390/crypto/ap_bus.h          |  12 ++
 drivers/s390/crypto/vfio_ap_drv.c     |   4 +-
 drivers/s390/crypto/vfio_ap_ops.c     | 215 +++++++++++++++++++++++---
 drivers/s390/crypto/vfio_ap_private.h |  15 +-
 5 files changed, 306 insertions(+), 29 deletions(-)

diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c
index b7653cec81ac..ccc87fb84c6d 100644
--- a/drivers/s390/crypto/ap_bus.c
+++ b/drivers/s390/crypto/ap_bus.c
@@ -82,6 +82,7 @@ static atomic64_t ap_scan_bus_count;
 static DECLARE_COMPLETION(ap_init_apqn_bindings_complete);
 
 static struct ap_config_info *ap_qci_info;
+static struct ap_config_info *ap_qci_info_old;
 
 /*
  * AP bus related debug feature things.
@@ -1579,6 +1580,50 @@ static int __match_queue_device_with_queue_id(struct device *dev, const void *da
 		&& AP_QID_QUEUE(to_ap_queue(dev)->qid) == (int)(long) data;
 }
 
+/* Helper function for notify_config_changed */
+static int __drv_notify_config_changed(struct device_driver *drv, void *data)
+{
+	struct ap_driver *ap_drv = to_ap_drv(drv);
+
+	if (try_module_get(drv->owner)) {
+		if (ap_drv->on_config_changed)
+			ap_drv->on_config_changed(ap_qci_info,
+						  ap_qci_info_old);
+		module_put(drv->owner);
+	}
+
+	return 0;
+}
+
+/* Notify all drivers about an qci config change */
+static inline void notify_config_changed(void)
+{
+	bus_for_each_drv(&ap_bus_type, NULL, NULL,
+			 __drv_notify_config_changed);
+}
+
+/* Helper function for notify_scan_complete */
+static int __drv_notify_scan_complete(struct device_driver *drv, void *data)
+{
+	struct ap_driver *ap_drv = to_ap_drv(drv);
+
+	if (try_module_get(drv->owner)) {
+		if (ap_drv->on_scan_complete)
+			ap_drv->on_scan_complete(ap_qci_info,
+						 ap_qci_info_old);
+		module_put(drv->owner);
+	}
+
+	return 0;
+}
+
+/* Notify all drivers about bus scan complete */
+static inline void notify_scan_complete(void)
+{
+	bus_for_each_drv(&ap_bus_type, NULL, NULL,
+			 __drv_notify_scan_complete);
+}
+
 /*
  * Helper function for ap_scan_bus().
  * Remove card device and associated queue devices.
@@ -1857,15 +1902,51 @@ static inline void ap_scan_adapter(int ap)
 	put_device(&ac->ap_dev.device);
 }
 
+/*
+ * ap_get_configuration
+ *
+ * Stores the host AP configuration information returned from the previous call
+ * to Query Configuration Information (QCI), then retrieves and stores the
+ * current AP configuration returned from QCI.
+ *
+ * Returns true if the host AP configuration changed between calls to QCI;
+ * otherwise, returns false.
+ */
+static bool ap_get_configuration(void)
+{
+	bool cfg_chg = false;
+
+	if (ap_qci_info) {
+		if (!ap_qci_info_old) {
+			ap_qci_info_old = kzalloc(sizeof(*ap_qci_info_old),
+						  GFP_KERNEL);
+			if (!ap_qci_info_old)
+				return false;
+		} else {
+			memcpy(ap_qci_info_old, ap_qci_info,
+			       sizeof(struct ap_config_info));
+		}
+		ap_fetch_qci_info(ap_qci_info);
+		cfg_chg = memcmp(ap_qci_info,
+				 ap_qci_info_old,
+				 sizeof(struct ap_config_info)) != 0;
+	}
+
+	return cfg_chg;
+}
+
 /**
  * ap_scan_bus(): Scan the AP bus for new devices
  * Runs periodically, workqueue timer (ap_config_time)
  */
 static void ap_scan_bus(struct work_struct *unused)
 {
-	int ap;
+	int ap, config_changed = 0;
 
-	ap_fetch_qci_info(ap_qci_info);
+	/* config change notify */
+	config_changed = ap_get_configuration();
+	if (config_changed)
+		notify_config_changed();
 	ap_select_domain();
 
 	AP_DBF_DBG("%s running\n", __func__);
@@ -1874,6 +1955,10 @@ static void ap_scan_bus(struct work_struct *unused)
 	for (ap = 0; ap <= ap_max_adapter_id; ap++)
 		ap_scan_adapter(ap);
 
+	/* scan complete notify */
+	if (config_changed)
+		notify_scan_complete();
+
 	/* check if there is at least one queue available with default domain */
 	if (ap_domain_index >= 0) {
 		struct device *dev =
diff --git a/drivers/s390/crypto/ap_bus.h b/drivers/s390/crypto/ap_bus.h
index 95c9da072f81..e91082bd159c 100644
--- a/drivers/s390/crypto/ap_bus.h
+++ b/drivers/s390/crypto/ap_bus.h
@@ -146,6 +146,18 @@ struct ap_driver {
 	int (*probe)(struct ap_device *);
 	void (*remove)(struct ap_device *);
 	int (*in_use)(unsigned long *apm, unsigned long *aqm);
+	/*
+	 * Called at the start of the ap bus scan function when
+	 * the crypto config information (qci) has changed.
+	 */
+	void (*on_config_changed)(struct ap_config_info *new_config_info,
+				  struct ap_config_info *old_config_info);
+	/*
+	 * Called at the end of the ap bus scan function when
+	 * the crypto config information (qci) has changed.
+	 */
+	void (*on_scan_complete)(struct ap_config_info *new_config_info,
+				 struct ap_config_info *old_config_info);
 };
 
 #define to_ap_drv(x) container_of((x), struct ap_driver, driver)
diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
index 8934471b7944..075495fc44c0 100644
--- a/drivers/s390/crypto/vfio_ap_drv.c
+++ b/drivers/s390/crypto/vfio_ap_drv.c
@@ -87,7 +87,7 @@ static int vfio_ap_matrix_dev_create(void)
 
 	/* Fill in config info via PQAP(QCI), if available */
 	if (test_facility(12)) {
-		ret = ap_qci(&matrix_dev->info);
+		ret = ap_qci(&matrix_dev->config_info);
 		if (ret)
 			goto matrix_alloc_err;
 	}
@@ -148,6 +148,8 @@ static int __init vfio_ap_init(void)
 	vfio_ap_drv.probe = vfio_ap_mdev_probe_queue;
 	vfio_ap_drv.remove = vfio_ap_mdev_remove_queue;
 	vfio_ap_drv.in_use = vfio_ap_mdev_resource_in_use;
+	vfio_ap_drv.on_config_changed = vfio_ap_on_cfg_changed;
+	vfio_ap_drv.on_scan_complete = vfio_ap_on_scan_complete;
 	vfio_ap_drv.ids = ap_queue_ids;
 
 	ret = ap_driver_register(&vfio_ap_drv, THIS_MODULE, VFIO_AP_DRV_NAME);
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index c147e3f43ae4..fdf0cc400000 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -335,24 +335,14 @@ static void vfio_ap_mdev_commit_apcb(struct ap_matrix_mdev *matrix_mdev)
 static void vfio_ap_mdev_filter_apcb(struct ap_matrix_mdev *matrix_mdev,
 				     struct ap_matrix *shadow_apcb)
 {
-	int ret;
 	unsigned long apid, apqi, apqn;
 
-	ret = ap_qci(&matrix_dev->info);
-	if (ret)
-		return;
-
-	/*
-	 * Copy the adapters, domains and control domains to the shadow_apcb
-	 * from the matrix mdev, but only those that are assigned to the host's
-	 * AP configuration.
-	 */
 	bitmap_and(shadow_apcb->apm, matrix_mdev->matrix.apm,
-		   (unsigned long *)matrix_dev->info.apm, AP_DEVICES);
+		   (unsigned long *)matrix_dev->config_info.apm, AP_DEVICES);
 	bitmap_and(shadow_apcb->aqm, matrix_mdev->matrix.aqm,
-		   (unsigned long *)matrix_dev->info.aqm, AP_DOMAINS);
+		   (unsigned long *)matrix_dev->config_info.aqm, AP_DOMAINS);
 	bitmap_and(shadow_apcb->adm, matrix_mdev->matrix.adm,
-		   (unsigned long *)matrix_dev->info.adm, AP_DOMAINS);
+		   (unsigned long *)matrix_dev->config_info.adm, AP_DOMAINS);
 
 	for_each_set_bit_inv(apid, shadow_apcb->apm, AP_DEVICES) {
 		for_each_set_bit_inv(apqi, shadow_apcb->aqm, AP_DOMAINS) {
@@ -385,7 +375,7 @@ static void vfio_ap_mdev_refresh_apcb(struct ap_matrix_mdev *matrix_mdev)
 {
 	struct ap_matrix shadow_apcb;
 
-	vfio_ap_matrix_init(&matrix_dev->info, &shadow_apcb);
+	vfio_ap_matrix_init(&matrix_dev->config_info, &shadow_apcb);
 	vfio_ap_mdev_filter_apcb(matrix_mdev, &shadow_apcb);
 
 	if (memcmp(&shadow_apcb, &matrix_mdev->shadow_apcb,
@@ -410,9 +400,9 @@ static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
 	}
 
 	matrix_mdev->mdev = mdev;
-	vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->matrix);
+	vfio_ap_matrix_init(&matrix_dev->config_info, &matrix_mdev->matrix);
 	init_waitqueue_head(&matrix_mdev->wait_for_kvm);
-	vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->shadow_apcb);
+	vfio_ap_matrix_init(&matrix_dev->config_info, &matrix_mdev->shadow_apcb);
 	hash_init(matrix_mdev->qtable);
 	mdev_set_drvdata(mdev, matrix_mdev);
 	matrix_mdev->pqap_hook.hook = handle_pqap;
@@ -935,7 +925,8 @@ static void vfio_ap_mdev_hot_plug_cdom(struct ap_matrix_mdev *matrix_mdev,
 				       unsigned long domid)
 {
 	if (!test_bit_inv(domid, matrix_mdev->shadow_apcb.adm) &&
-	    test_bit_inv(domid, (unsigned long *)matrix_dev->info.adm)) {
+	    test_bit_inv(domid,
+			 (unsigned long *)matrix_dev->config_info.adm)) {
 		set_bit_inv(domid, matrix_mdev->shadow_apcb.adm);
 		vfio_ap_mdev_commit_apcb(matrix_mdev);
 	}
@@ -1579,15 +1570,27 @@ int vfio_ap_mdev_probe_queue(struct ap_device *apdev)
 	vfio_ap_queue_link_mdev(q);
 	if (q->matrix_mdev) {
 		/*
-		 * If the KVM pointer is in the process of being set, wait until the
-		 * process has completed.
+		 * If we are in the process of adding adapters and/or domains
+		 * due to a change to the host's AP configuration, it is more
+		 * efficient to refresh the guest's APCB in a single operation
+		 * after the AP bus scan is complete (see the
+		 * vfio_ap_on_scan_complete function) rather than to do the
+		 * refresh for each queue added, so if that is not the case,
+		 * let's go ahead and refresh the guest's APCB here.
 		 */
-		wait_event_cmd(q->matrix_mdev->wait_for_kvm,
-			       !q->matrix_mdev->kvm_busy,
-			       mutex_unlock(&matrix_dev->lock),
-			       mutex_lock(&matrix_dev->lock));
+		if (bitmap_empty(matrix_dev->ap_add, AP_DEVICES) &&
+		    bitmap_empty(matrix_dev->aq_add, AP_DOMAINS)) {
+			/*
+			 * If the KVM pointer is in the process of being set, wait until the
+			 * process has completed.
+			 */
+			wait_event_cmd(q->matrix_mdev->wait_for_kvm,
+				       !q->matrix_mdev->kvm_busy,
+				       mutex_unlock(&matrix_dev->lock),
+				       mutex_lock(&matrix_dev->lock));
 
-		vfio_ap_mdev_refresh_apcb(q->matrix_mdev);
+			vfio_ap_mdev_refresh_apcb(q->matrix_mdev);
+		}
 	}
 	dev_set_drvdata(&apdev->device, q);
 	mutex_unlock(&matrix_dev->lock);
@@ -1629,8 +1632,172 @@ int vfio_ap_mdev_resource_in_use(unsigned long *apm, unsigned long *aqm)
 
 	if (!mutex_trylock(&matrix_dev->lock))
 		return -EBUSY;
+
 	ret = vfio_ap_mdev_verify_no_sharing(apm, aqm);
 	mutex_unlock(&matrix_dev->lock);
 
 	return ret;
 }
+
+/*
+ * vfio_ap_mdev_unlink_apids
+ *
+ * @matrix_mdev: The matrix mediated device
+ *
+ * @apid_rem: The bitmap specifying the APIDs of the adapters removed from
+ *	      the host's AP configuration
+ *
+ * Unlinks @matrix_mdev from each queue assigned to @matrix_mdev whose APQN
+ * contains an APID specified in @apid_rem.
+ *
+ * Returns true if one or more AP queue devices were unlinked; otherwise,
+ * returns false.
+ */
+static bool vfio_ap_mdev_unlink_apids(struct ap_matrix_mdev *matrix_mdev,
+				      unsigned long *apid_rem)
+{
+	int bkt, apid;
+	bool q_unlinked = false;
+	struct vfio_ap_queue *q;
+
+	hash_for_each(matrix_mdev->qtable, bkt, q, mdev_qnode) {
+		apid = AP_QID_CARD(q->apqn);
+		if (test_bit_inv(apid, apid_rem)) {
+			vfio_ap_mdev_reset_queue(q, 1);
+			vfio_ap_mdev_unlink_queue(q);
+			q_unlinked = true;
+		}
+	}
+
+	return q_unlinked;
+}
+
+/*
+ * vfio_ap_mdev_unlink_apqis
+ *
+ * @matrix_mdev: The matrix mediated device
+ *
+ * @apqi_rem: The bitmap specifying the APQIs of the domains removed from
+ *	      the host's AP configuration
+ *
+ * Unlinks @matrix_mdev from each queue assigned to @matrix_mdev whose APQN
+ * contains an APQI specified in @apqi_rem.
+ *
+ * Returns true if one or more AP queue devices were unlinked; otherwise,
+ * returns false.
+ */
+static bool vfio_ap_mdev_unlink_apqis(struct ap_matrix_mdev *matrix_mdev,
+				      unsigned long *apqi_rem)
+{
+	int bkt, apqi;
+	bool q_unlinked = false;
+	struct vfio_ap_queue *q;
+
+	hash_for_each(matrix_mdev->qtable, bkt, q, mdev_qnode) {
+		apqi = AP_QID_QUEUE(q->apqn);
+		if (test_bit_inv(apqi, apqi_rem)) {
+			vfio_ap_mdev_reset_queue(q, 1);
+			vfio_ap_mdev_unlink_queue(q);
+			q_unlinked = true;
+		}
+	}
+
+	return q_unlinked;
+}
+
+static void vfio_ap_mdev_on_cfg_remove(void)
+{
+	bool refresh_apcb = false;
+	int ap_remove, aq_remove;
+	struct ap_matrix_mdev *matrix_mdev;
+	DECLARE_BITMAP(aprem, AP_DEVICES);
+	DECLARE_BITMAP(aqrem, AP_DOMAINS);
+	unsigned long *cur_apm, *cur_aqm, *prev_apm, *prev_aqm;
+
+	cur_apm = (unsigned long *)matrix_dev->config_info.apm;
+	cur_aqm = (unsigned long *)matrix_dev->config_info.aqm;
+	prev_apm = (unsigned long *)matrix_dev->config_info_prev.apm;
+	prev_aqm = (unsigned long *)matrix_dev->config_info_prev.aqm;
+
+	ap_remove = bitmap_andnot(aprem, prev_apm, cur_apm, AP_DEVICES);
+	aq_remove = bitmap_andnot(aqrem, prev_aqm, cur_aqm, AP_DOMAINS);
+
+	if (!ap_remove && !aq_remove)
+		return;
+
+	list_for_each_entry(matrix_mdev, &matrix_dev->mdev_list, node) {
+		if (ap_remove)
+			refresh_apcb = vfio_ap_mdev_unlink_apids(matrix_mdev,
+								 aprem);
+
+		if (aq_remove)
+			refresh_apcb = vfio_ap_mdev_unlink_apqis(matrix_mdev,
+								 aqrem);
+
+		if (refresh_apcb)
+			vfio_ap_mdev_refresh_apcb(matrix_mdev);
+	}
+}
+
+static void vfio_ap_mdev_on_cfg_add(void)
+{
+	unsigned long *cur_apm, *cur_aqm, *cur_adm;
+	unsigned long *prev_apm, *prev_aqm, *prev_adm;
+
+	cur_apm = (unsigned long *)matrix_dev->config_info.apm;
+	cur_aqm = (unsigned long *)matrix_dev->config_info.aqm;
+	cur_adm = (unsigned long *)matrix_dev->config_info.adm;
+
+	prev_apm = (unsigned long *)matrix_dev->config_info_prev.apm;
+	prev_aqm = (unsigned long *)matrix_dev->config_info_prev.aqm;
+	prev_adm = (unsigned long *)matrix_dev->config_info_prev.adm;
+
+	bitmap_andnot(matrix_dev->ap_add, cur_apm, prev_apm, AP_DEVICES);
+	bitmap_andnot(matrix_dev->aq_add, cur_aqm, prev_aqm, AP_DOMAINS);
+	bitmap_andnot(matrix_dev->ad_add, cur_adm, prev_adm, AP_DOMAINS);
+}
+
+void vfio_ap_init_mdev_matrixes(struct ap_config_info *config_info)
+{
+	struct ap_matrix_mdev *matrix_mdev;
+
+	list_for_each_entry(matrix_mdev, &matrix_dev->mdev_list, node) {
+		vfio_ap_matrix_init(config_info, &matrix_mdev->matrix);
+		vfio_ap_matrix_init(config_info, &matrix_mdev->shadow_apcb);
+	}
+}
+
+void vfio_ap_on_cfg_changed(struct ap_config_info *new_config_info,
+			    struct ap_config_info *old_config_info)
+{
+	mutex_lock(&matrix_dev->lock);
+	memcpy(&matrix_dev->config_info, new_config_info,
+	       sizeof(struct ap_config_info));
+	memcpy(&matrix_dev->config_info_prev, old_config_info,
+	       sizeof(struct ap_config_info));
+	vfio_ap_init_mdev_matrixes(new_config_info);
+	vfio_ap_mdev_on_cfg_remove();
+	vfio_ap_mdev_on_cfg_add();
+	mutex_unlock(&matrix_dev->lock);
+}
+
+void vfio_ap_on_scan_complete(struct ap_config_info *new_config_info,
+			      struct ap_config_info *old_config_info)
+{
+	struct ap_matrix_mdev *matrix_mdev;
+
+	mutex_lock(&matrix_dev->lock);
+	list_for_each_entry(matrix_mdev, &matrix_dev->mdev_list, node) {
+		if (bitmap_intersects(matrix_mdev->matrix.apm,
+				      matrix_dev->ap_add, AP_DEVICES) ||
+		    bitmap_intersects(matrix_mdev->matrix.aqm,
+				      matrix_dev->aq_add, AP_DOMAINS) ||
+		    bitmap_intersects(matrix_mdev->matrix.adm,
+				      matrix_dev->ad_add, AP_DOMAINS))
+			vfio_ap_mdev_refresh_apcb(matrix_mdev);
+	}
+
+	bitmap_clear(matrix_dev->ap_add, 0, AP_DEVICES);
+	bitmap_clear(matrix_dev->aq_add, 0, AP_DOMAINS);
+	mutex_unlock(&matrix_dev->lock);
+}
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index 601012751a4a..a1e0ee395e95 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -29,7 +29,9 @@
  * ap_matrix_dev - the AP matrix device structure
  * @device:	generic device structure associated with the AP matrix device
  * @available_instances: number of mediated matrix devices that can be created
- * @info:	the struct containing the output from the PQAP(QCI) instruction
+ * @config_info: the current host AP configuration information
+ * @config_info_prev: the host AP configuration information from the previous
+ *		      configuration changed notification
  * mdev_list:	the list of mediated matrix devices created
  * lock:	mutex for locking the AP matrix device. This lock will be
  *		taken every time we fiddle with state managed by the vfio_ap
@@ -40,10 +42,14 @@
 struct ap_matrix_dev {
 	struct device device;
 	atomic_t available_instances;
-	struct ap_config_info info;
+	struct ap_config_info config_info;
+	struct ap_config_info config_info_prev;
 	struct list_head mdev_list;
 	struct mutex lock;
 	struct ap_driver  *vfio_ap_drv;
+	DECLARE_BITMAP(ap_add, AP_DEVICES);
+	DECLARE_BITMAP(aq_add, AP_DOMAINS);
+	DECLARE_BITMAP(ad_add, AP_DOMAINS);
 };
 
 extern struct ap_matrix_dev *matrix_dev;
@@ -111,4 +117,9 @@ void vfio_ap_mdev_remove_queue(struct ap_device *queue);
 
 int vfio_ap_mdev_resource_in_use(unsigned long *apm, unsigned long *aqm);
 
+void vfio_ap_on_cfg_changed(struct ap_config_info *new_config_info,
+			    struct ap_config_info *old_config_info);
+void vfio_ap_on_scan_complete(struct ap_config_info *new_config_info,
+			      struct ap_config_info *old_config_info);
+
 #endif /* _VFIO_AP_PRIVATE_H_ */
-- 
2.21.3