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Subject[PATCH v3 1/9] s390: vfio_ap: link the vfio_ap devices to the vfio_ap bus subsystem
Date
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 vfio_ap bus and with that the vfio_ap
bus subsytem, and make the matrix device reside within it.

We restrict the number of allowed devices to a single one.

Doing this we need to suppress the forced link from the matrix device to
the vfio_ap driver and we suppress 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.

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
---
drivers/s390/crypto/vfio_ap_drv.c | 63 +++++++++++++++++++++++++++++++----
drivers/s390/crypto/vfio_ap_ops.c | 4 +--
drivers/s390/crypto/vfio_ap_private.h | 1 +
3 files changed, 60 insertions(+), 8 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
index 31c6c84..1fd5fe6 100644
--- a/drivers/s390/crypto/vfio_ap_drv.c
+++ b/drivers/s390/crypto/vfio_ap_drv.c
@@ -24,8 +24,9 @@ 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 matrix_driver {
+ struct device_driver drv;
+ int device_count;
};

struct ap_matrix_dev *matrix_dev;
@@ -62,6 +63,41 @@ 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 = "vfio_ap",
+ .match = &matrix_bus_match,
+};
+
+static int matrix_probe(struct device *dev);
+static int matrix_remove(struct device *dev);
+static struct matrix_driver matrix_driver = {
+ .drv = {
+ .name = "vfio_ap",
+ .bus = &matrix_bus,
+ .probe = matrix_probe,
+ .remove = matrix_remove,
+ },
+};
+
+static int matrix_probe(struct device *dev)
+{
+ if (matrix_driver.device_count)
+ return -EEXIST;
+ matrix_driver.device_count++;
+ return 0;
+}
+
+static int matrix_remove(struct device *dev)
+{
+ matrix_driver.device_count--;
+ return 0;
+}
+
static int vfio_ap_matrix_dev_create(void)
{
int ret;
@@ -71,6 +107,10 @@ 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;
@@ -87,30 +127,41 @@ 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.drv);
+ 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.drv);
device_unregister(&matrix_dev->device);
- root_device_unregister(matrix_dev->device.parent);
+ bus_unregister(&matrix_bus);
+ root_device_unregister(root_device);
}

static 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 272ef42..900b9cf 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
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