[PATCH 1/6] mdev: class id support

Jason Wang
2019-09-23T13:04:25Z

Mdev bus only supports vfio driver right now, so it doesn't implement
match method. But in the future, we may add drivers other than vfio,
one example is virtio-mdev[1] driver. This means we need to add device
class id support in bus match method to pair the mdev device and mdev
driver correctly.

So this patch adds id_table to mdev_driver and class_id for mdev
parent with the match method for mdev bus.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
Documentation/driver-api/vfio-mediated-device.rst | 7 +++++--
drivers/gpu/drm/i915/gvt/kvmgt.c | 2 +-
drivers/s390/cio/vfio_ccw_ops.c | 2 +-
drivers/s390/crypto/vfio_ap_ops.c | 3 ++-
drivers/vfio/mdev/mdev_core.c | 14 ++++++++++++--
drivers/vfio/mdev/mdev_driver.c | 14 ++++++++++++++
drivers/vfio/mdev/mdev_private.h | 1 +
drivers/vfio/mdev/vfio_mdev.c | 6 ++++++
include/linux/mdev.h | 7 ++++++-
include/linux/mod_devicetable.h | 8 ++++++++
samples/vfio-mdev/mbochs.c | 2 +-
samples/vfio-mdev/mdpy.c | 2 +-
samples/vfio-mdev/mtty.c | 2 +-
13 files changed, 59 insertions(+), 11 deletions(-)

diff --git a/Documentation/driver-api/vfio-mediated-device.rst b/Documentation/driver-api/vfio-mediated-device.rst
index 25eb7d5b834b..0e052072e1d8 100644
--- a/Documentation/driver-api/vfio-mediated-device.rst
+++ b/Documentation/driver-api/vfio-mediated-device.rst
@@ -102,12 +102,14 @@ structure to represent a mediated device's driver::
* @probe: called when new device created
* @remove: called when device removed
* @driver: device driver structure
+ * @id_table: the ids serviced by this driver.
*/
struct mdev_driver {
const char *name;
int (*probe) (struct device *dev);
void (*remove) (struct device *dev);
struct device_driver driver;
+ const struct mdev_class_id *id_table;
};

A mediated bus driver for mdev should use this structure in the function calls
@@ -116,7 +118,7 @@ to register and unregister itself with the core driver:
* Register::

extern int mdev_register_driver(struct mdev_driver *drv,
- struct module *owner);
+ struct module *owner);

* Unregister::

@@ -163,7 +165,8 @@ A driver should use the mdev_parent_ops structure in the function call to
register itself with the mdev core driver::

extern int mdev_register_device(struct device *dev,
- const struct mdev_parent_ops *ops);
+ const struct mdev_parent_ops *ops,
+ u8 class_id);

However, the mdev_parent_ops structure is not required in the function call
that a driver should use to unregister itself with the mdev core driver::
diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index 23aa3e50cbf8..19d51a35f019 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -1625,7 +1625,7 @@ static int kvmgt_host_init(struct device *dev, void *gvt, const void *ops)
return -EFAULT;
intel_vgpu_ops.supported_type_groups = kvm_vgpu_type_groups;

- return mdev_register_device(dev, &intel_vgpu_ops);
+ return mdev_register_vfio_device(dev, &intel_vgpu_ops);
}

static void kvmgt_host_exit(struct device *dev)
diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index f0d71ab77c50..246ff0f80944 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -588,7 +588,7 @@ static const struct mdev_parent_ops vfio_ccw_mdev_ops = {

int vfio_ccw_mdev_reg(struct subchannel *sch)
{
- return mdev_register_device(&sch->dev, &vfio_ccw_mdev_ops);
+ return mdev_register_vfio_device(&sch->dev, &vfio_ccw_mdev_ops);
}

void vfio_ccw_mdev_unreg(struct subchannel *sch)
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 5c0f53c6dde7..7487fc39d2c5 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -1295,7 +1295,8 @@ int vfio_ap_mdev_register(void)
{
atomic_set(&matrix_dev->available_instances, MAX_ZDEV_ENTRIES_EXT);

- return mdev_register_device(&matrix_dev->device, &vfio_ap_matrix_ops);
+ return mdev_register_vfio_device(&matrix_dev->device,
+ &vfio_ap_matrix_ops);
}

void vfio_ap_mdev_unregister(void)
diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
index b558d4cfd082..a02c256a3514 100644
--- a/drivers/vfio/mdev/mdev_core.c
+++ b/drivers/vfio/mdev/mdev_core.c
@@ -135,11 +135,14 @@ static int mdev_device_remove_cb(struct device *dev, void *data)
* mdev_register_device : Register a device
* @dev: device structure representing parent device.
* @ops: Parent device operation structure to be registered.
+ * @id: device id.
*
* Add device to list of registered parent devices.
* Returns a negative value on error, otherwise 0.
*/
-int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops)
+int mdev_register_device(struct device *dev,
+ const struct mdev_parent_ops *ops,
+ u8 class_id)
{
int ret;
struct mdev_parent *parent;
@@ -175,6 +178,7 @@ int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops)

parent->dev = dev;
parent->ops = ops;
+ parent->class_id = class_id;

if (!mdev_bus_compat_class) {
mdev_bus_compat_class = class_compat_register("mdev_bus");
@@ -208,7 +212,13 @@ int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops)
put_device(dev);
return ret;
}
-EXPORT_SYMBOL(mdev_register_device);
+
+int mdev_register_vfio_device(struct device *dev,
+ const struct mdev_parent_ops *ops)
+{
+ return mdev_register_device(dev, ops, MDEV_ID_VFIO);
+}
+EXPORT_SYMBOL(mdev_register_vfio_device);

/*
* mdev_unregister_device : Unregister a parent device
diff --git a/drivers/vfio/mdev/mdev_driver.c b/drivers/vfio/mdev/mdev_driver.c
index 0d3223aee20b..b70bbebc9dd3 100644
--- a/drivers/vfio/mdev/mdev_driver.c
+++ b/drivers/vfio/mdev/mdev_driver.c
@@ -69,8 +69,22 @@ static int mdev_remove(struct device *dev)
return 0;
}

+static int mdev_match(struct device *dev, struct device_driver *drv)
+{
+ unsigned int i;
+ struct mdev_device *mdev = to_mdev_device(dev);
+ struct mdev_driver *mdrv = to_mdev_driver(drv);
+ const struct mdev_class_id *ids = mdrv->id_table;
+
+ for (i = 0; ids[i].id; i++)
+ if (ids[i].id == mdev->parent->class_id)
+ return 1;
+ return 0;
+}
+
struct bus_type mdev_bus_type = {
.name = "mdev",
+ .match = mdev_match,
.probe = mdev_probe,
.remove = mdev_remove,
};
diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
index 7d922950caaf..e58b07c866b1 100644
--- a/drivers/vfio/mdev/mdev_private.h
+++ b/drivers/vfio/mdev/mdev_private.h
@@ -22,6 +22,7 @@ struct mdev_parent {
struct list_head type_list;
/* Synchronize device creation/removal with parent unregistration */
struct rw_semaphore unreg_sem;
+ u8 class_id;
};

struct mdev_device {
diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
index 30964a4e0a28..fd2a4d9a3f26 100644
--- a/drivers/vfio/mdev/vfio_mdev.c
+++ b/drivers/vfio/mdev/vfio_mdev.c
@@ -120,10 +120,16 @@ static void vfio_mdev_remove(struct device *dev)
vfio_del_group_dev(dev);
}

+static struct mdev_class_id id_table[] = {
+ { MDEV_ID_VFIO },
+ { 0 },
+};
+
static struct mdev_driver vfio_mdev_driver = {
.name = "vfio_mdev",
.probe = vfio_mdev_probe,
.remove = vfio_mdev_remove,
+ .id_table = id_table,
};

static int __init vfio_mdev_init(void)
diff --git a/include/linux/mdev.h b/include/linux/mdev.h
index 0ce30ca78db0..3ebae310f599 100644
--- a/include/linux/mdev.h
+++ b/include/linux/mdev.h
@@ -118,6 +118,7 @@ struct mdev_type_attribute mdev_type_attr_##_name = \
* @probe: called when new device created
* @remove: called when device removed
* @driver: device driver structure
+ * @id_table: the ids serviced by this driver.
*
**/
struct mdev_driver {
@@ -125,6 +126,7 @@ struct mdev_driver {
int (*probe)(struct device *dev);
void (*remove)(struct device *dev);
struct device_driver driver;
+ const struct mdev_class_id *id_table;
};

#define to_mdev_driver(drv) container_of(drv, struct mdev_driver, driver)
@@ -135,7 +137,8 @@ const guid_t *mdev_uuid(struct mdev_device *mdev);

extern struct bus_type mdev_bus_type;

-int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops);
+int mdev_register_vfio_device(struct device *dev,
+ const struct mdev_parent_ops *ops);
void mdev_unregister_device(struct device *dev);

int mdev_register_driver(struct mdev_driver *drv, struct module *owner);
@@ -145,4 +148,6 @@ struct device *mdev_parent_dev(struct mdev_device *mdev);
struct device *mdev_dev(struct mdev_device *mdev);
struct mdev_device *mdev_from_dev(struct device *dev);

+#define MDEV_ID_VFIO 1 /* VFIO device */
+
#endif /* MDEV_H */
diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
index 5714fd35a83c..f32c6e44fb1a 100644
--- a/include/linux/mod_devicetable.h
+++ b/include/linux/mod_devicetable.h
@@ -821,4 +821,12 @@ struct wmi_device_id {
const void *context;
};

+/**
+ * struct mdev_class_id - MDEV device class identifier
+ * @id: Used to identify a specific class of device, e.g vfio-mdev device.
+ */
+struct mdev_class_id {
+ __u16 id;
+};
+
#endif /* LINUX_MOD_DEVICETABLE_H */
diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c
index ac5c8c17b1ff..71a4469be85d 100644
--- a/samples/vfio-mdev/mbochs.c
+++ b/samples/vfio-mdev/mbochs.c
@@ -1468,7 +1468,7 @@ static int __init mbochs_dev_init(void)
if (ret)
goto failed2;

- ret = mdev_register_device(&mbochs_dev, &mdev_fops);
+ ret = mdev_register_vfio_device(&mbochs_dev, &mdev_fops);
if (ret)
goto failed3;

diff --git a/samples/vfio-mdev/mdpy.c b/samples/vfio-mdev/mdpy.c
index cc86bf6566e4..d3029dd27d91 100644
--- a/samples/vfio-mdev/mdpy.c
+++ b/samples/vfio-mdev/mdpy.c
@@ -775,7 +775,7 @@ static int __init mdpy_dev_init(void)
if (ret)
goto failed2;

- ret = mdev_register_device(&mdpy_dev, &mdev_fops);
+ ret = mdev_register_vfio_device(&mdpy_dev, &mdev_fops);
if (ret)
goto failed3;

diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
index 92e770a06ea2..744c88a6b22c 100644
--- a/samples/vfio-mdev/mtty.c
+++ b/samples/vfio-mdev/mtty.c
@@ -1468,7 +1468,7 @@ static int __init mtty_dev_init(void)
if (ret)
goto failed2;

- ret = mdev_register_device(&mtty_dev.dev, &mdev_fops);
+ ret = mdev_register_vfio_device(&mtty_dev.dev, &mdev_fops);
if (ret)
goto failed3;

--
2.19.1