[SRU][Disco][Cosmic][Bionic][Patch 1/1] s390: vfio_ap: link the vfio_ap devices to the vfio_ap bus subsystem

[frank.heimes at canonical.com]

BugLink: http://bugs.launchpad.net/bugs/1818854

s390: vfio_ap: link the vfio_ap devices to the vfio_ap bus subsystem

Libudev relies on having a subsystem link for non-root devices. To
avoid libudev (and potentially other userspace tools) choking on the
matrix device let us introduce a matrix bus and with it the matrix
bus subsytem. Also make the matrix device reside within the matrix
bus.

Doing this we remove the forced link from the matrix device to the
vfio_ap driver and the device_type we do not need anymore.

Since the associated matrix driver is not the vfio_ap driver any more,
we have to change the search for the devices on the vfio_ap driver in
the function vfio_ap_verify_queue_reserved.
Fixes: 1fde573413b5 ("s390: vfio-ap: base implementation of VFIO AP device driver")
Cc: stable at vger.kernel.org

Reported-by: Marc Hartmayer <mhartmay at linux.ibm.com>
Reported-by: Christian Borntraeger <borntraeger at de.ibm.com>
Signed-off-by: Pierre Morel <pmorel at linux.ibm.com>
Tested-by: Christian Borntraeger <borntraeger at de.ibm.com>
Reviewed-by: Cornelia Huck <cohuck at redhat.com>
Reviewed-by: Tony Krowiak <akrowiak at linux.ibm.com>
Acked-by: Halil Pasic <pasic at linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky at de.ibm.com>
(cherry picked from commit 36360658eb5a6cf04bb9f2704d1e4ce54037ec99)
Signed-off-by: Frank Heimes <frank.heimes at canonical.com>
---
 drivers/s390/crypto/vfio_ap_drv.c     | 44 ++++++++++++++++++++++++++++-------
 drivers/s390/crypto/vfio_ap_ops.c     |  4 ++--
 drivers/s390/crypto/vfio_ap_private.h |  1 +
 3 files changed, 38 insertions(+), 11 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
index 8b51821..05d16ed 100644
--- a/drivers/s390/crypto/vfio_ap_drv.c
+++ b/drivers/s390/crypto/vfio_ap_drv.c
@@ -14,7 +14,6 @@
 #include "vfio_ap_private.h"
 
 #define VFIO_AP_ROOT_NAME "vfio_ap"
-#define VFIO_AP_DEV_TYPE_NAME "ap_matrix"
 #define VFIO_AP_DEV_NAME "matrix"
 
 MODULE_AUTHOR("IBM Corporation");
@@ -23,10 +22,6 @@ MODULE_LICENSE("GPL v2");
 
 static struct ap_driver vfio_ap_drv;
 
-static struct device_type vfio_ap_dev_type = {
-	.name = VFIO_AP_DEV_TYPE_NAME,
-};
-
 struct ap_matrix_dev *matrix_dev;
 
 /* Only type 10 adapters (CEX4 and later) are supported
@@ -61,6 +56,22 @@ static void vfio_ap_matrix_dev_release(struct device *dev)
 	kfree(matrix_dev);
 }
 
+static int matrix_bus_match(struct device *dev, struct device_driver *drv)
+{
+	return 1;
+}
+
+static struct bus_type matrix_bus = {
+	.name = "matrix",
+	.match = &matrix_bus_match,
+};
+
+static struct device_driver matrix_driver = {
+	.name = "vfio_ap",
+	.bus = &matrix_bus,
+	.suppress_bind_attrs = true,
+};
+
 static int vfio_ap_matrix_dev_create(void)
 {
 	int ret;
@@ -70,6 +81,10 @@ static int vfio_ap_matrix_dev_create(void)
 	if (IS_ERR(root_device))
 		return PTR_ERR(root_device);
 
+	ret = bus_register(&matrix_bus);
+	if (ret)
+		goto bus_register_err;
+
 	matrix_dev = kzalloc(sizeof(*matrix_dev), GFP_KERNEL);
 	if (!matrix_dev) {
 		ret = -ENOMEM;
@@ -86,30 +101,41 @@ static int vfio_ap_matrix_dev_create(void)
 	mutex_init(&matrix_dev->lock);
 	INIT_LIST_HEAD(&matrix_dev->mdev_list);
 
-	matrix_dev->device.type = &vfio_ap_dev_type;
 	dev_set_name(&matrix_dev->device, "%s", VFIO_AP_DEV_NAME);
 	matrix_dev->device.parent = root_device;
+	matrix_dev->device.bus = &matrix_bus;
 	matrix_dev->device.release = vfio_ap_matrix_dev_release;
-	matrix_dev->device.driver = &vfio_ap_drv.driver;
+	matrix_dev->vfio_ap_drv = &vfio_ap_drv;
 
 	ret = device_register(&matrix_dev->device);
 	if (ret)
 		goto matrix_reg_err;
 
+	ret = driver_register(&matrix_driver);
+	if (ret)
+		goto matrix_drv_err;
+
 	return 0;
 
+matrix_drv_err:
+	device_unregister(&matrix_dev->device);
 matrix_reg_err:
 	put_device(&matrix_dev->device);
 matrix_alloc_err:
+	bus_unregister(&matrix_bus);
+bus_register_err:
 	root_device_unregister(root_device);
-
 	return ret;
 }
 
 static void vfio_ap_matrix_dev_destroy(void)
 {
+	struct device *root_device = matrix_dev->device.parent;
+
+	driver_unregister(&matrix_driver);
 	device_unregister(&matrix_dev->device);
-	root_device_unregister(matrix_dev->device.parent);
+	bus_unregister(&matrix_bus);
+	root_device_unregister(root_device);
 }
 
 int __init vfio_ap_init(void)
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index ea99165..42d850f 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -198,8 +198,8 @@ static int vfio_ap_verify_queue_reserved(unsigned long *apid,
 	qres.apqi = apqi;
 	qres.reserved = false;
 
-	ret = driver_for_each_device(matrix_dev->device.driver, NULL, &qres,
-				     vfio_ap_has_queue);
+	ret = driver_for_each_device(&matrix_dev->vfio_ap_drv->driver, NULL,
+				     &qres, vfio_ap_has_queue);
 	if (ret)
 		return ret;
 
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index 5675492..76b7f98 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -40,6 +40,7 @@ struct ap_matrix_dev {
 	struct ap_config_info info;
 	struct list_head mdev_list;
 	struct mutex lock;
+	struct ap_driver  *vfio_ap_drv;
 };
 
 extern struct ap_matrix_dev *matrix_dev;
-- 
2.7.4