Re: [PATCH V5 1/6] mdev: class id support

[Jason Wang <jasowang@redhat.com>]

On 2019/10/24 上午5:42, Alex Williamson wrote:
> On Wed, 23 Oct 2019 21:07:47 +0800
> Jason Wang <jasowang@redhat.com> wrote:
>
>> 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,
>> the first driver could be virtio-mdev. 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
>> device with the match method for mdev bus.
>>
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>> ---
>>   .../driver-api/vfio-mediated-device.rst       |  5 +++++
>>   drivers/gpu/drm/i915/gvt/kvmgt.c              |  1 +
>>   drivers/s390/cio/vfio_ccw_ops.c               |  1 +
>>   drivers/s390/crypto/vfio_ap_ops.c             |  1 +
>>   drivers/vfio/mdev/mdev_core.c                 | 18 +++++++++++++++
>>   drivers/vfio/mdev/mdev_driver.c               | 22 +++++++++++++++++++
>>   drivers/vfio/mdev/mdev_private.h              |  1 +
>>   drivers/vfio/mdev/vfio_mdev.c                 |  6 +++++
>>   include/linux/mdev.h                          |  8 +++++++
>>   include/linux/mod_devicetable.h               |  8 +++++++
>>   samples/vfio-mdev/mbochs.c                    |  1 +
>>   samples/vfio-mdev/mdpy.c                      |  1 +
>>   samples/vfio-mdev/mtty.c                      |  1 +
>>   13 files changed, 74 insertions(+)
>>
>> diff --git a/Documentation/driver-api/vfio-mediated-device.rst b/Documentation/driver-api/vfio-mediated-device.rst
>> index 25eb7d5b834b..6709413bee29 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
>> @@ -170,6 +172,9 @@ that a driver should use to unregister itself with the mdev core driver::
>>   
>>   	extern void mdev_unregister_device(struct device *dev);
>>   
>> +It is also required to specify the class_id in create() callback through::
>> +
>> +	int mdev_set_class(struct mdev_device *mdev, u16 id);
>>   
>>   Mediated Device Management Interface Through sysfs
>>   ==================================================
>> diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
>> index 343d79c1cb7e..6420f0dbd31b 100644
>> --- a/drivers/gpu/drm/i915/gvt/kvmgt.c
>> +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
>> @@ -678,6 +678,7 @@ static int intel_vgpu_create(struct kobject *kobj, struct mdev_device *mdev)
>>   		     dev_name(mdev_dev(mdev)));
>>   	ret = 0;
>>   
>> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>>   out:
>>   	return ret;
>>   }
>> diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
>> index f0d71ab77c50..cf2c013ae32f 100644
>> --- a/drivers/s390/cio/vfio_ccw_ops.c
>> +++ b/drivers/s390/cio/vfio_ccw_ops.c
>> @@ -129,6 +129,7 @@ static int vfio_ccw_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
>>   			   private->sch->schid.ssid,
>>   			   private->sch->schid.sch_no);
>>   
>> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>>   	return 0;
>>   }
>>   
>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
>> index 5c0f53c6dde7..07c31070afeb 100644
>> --- a/drivers/s390/crypto/vfio_ap_ops.c
>> +++ b/drivers/s390/crypto/vfio_ap_ops.c
>> @@ -343,6 +343,7 @@ static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
>>   	list_add(&matrix_mdev->node, &matrix_dev->mdev_list);
>>   	mutex_unlock(&matrix_dev->lock);
>>   
>> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>>   	return 0;
>>   }
>>   
>> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
>> index b558d4cfd082..3a9c52d71b4e 100644
>> --- a/drivers/vfio/mdev/mdev_core.c
>> +++ b/drivers/vfio/mdev/mdev_core.c
>> @@ -45,6 +45,16 @@ void mdev_set_drvdata(struct mdev_device *mdev, void *data)
>>   }
>>   EXPORT_SYMBOL(mdev_set_drvdata);
>>   
>> +/* Specify the class for the mdev device, this must be called during
>> + * create() callback.
>> + */
>> +void mdev_set_class(struct mdev_device *mdev, u16 id)
>> +{
>> +	WARN_ON(mdev->class_id);
>> +	mdev->class_id = id;
>> +}
>> +EXPORT_SYMBOL(mdev_set_class);
>> +
>>   struct device *mdev_dev(struct mdev_device *mdev)
>>   {
>>   	return &mdev->dev;
>> @@ -135,6 +145,7 @@ 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: class id.
>>    *
>>    * Add device to list of registered parent devices.
>>    * Returns a negative value on error, otherwise 0.
>> @@ -324,6 +335,13 @@ int mdev_device_create(struct kobject *kobj,
>>   	if (ret)
>>   		goto ops_create_fail;
>>   
>> +	if (!mdev->class_id) {
>> +		ret = -EINVAL;
>> +		WARN(1, "class id must be specified for device %s\n",
>> +		     dev_name(dev));
> Nit, dev_warn(dev, "mdev vendor driver failed to specify device class\n");


Will fix.


>
>> +		goto add_fail;
>> +	}
>> +
>>   	ret = device_add(&mdev->dev);
>>   	if (ret)
>>   		goto add_fail;
>> diff --git a/drivers/vfio/mdev/mdev_driver.c b/drivers/vfio/mdev/mdev_driver.c
>> index 0d3223aee20b..319d886ffaf7 100644
>> --- a/drivers/vfio/mdev/mdev_driver.c
>> +++ b/drivers/vfio/mdev/mdev_driver.c
>> @@ -69,8 +69,30 @@ 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;
>> +
> Nit, as we start to allow new mdev bus drivers, mdev-core might want to
> protect itself from a NULL id_table, by either failing the
> mdev_register_driver() or failing the match here.  I think such a
> condition would segfault as written here, but clearly we don't have
> such external drivers yet.  Thanks,


I'm not sure I get the point here. My understanding is that mdev-core 
won't try to be matched here since it was not a complete mdev device.

Thanks


>
> Alex
>
>> +	for (i = 0; ids[i].id; i++)
>> +		if (ids[i].id == mdev->class_id)
>> +			return 1;
>> +	return 0;
>> +}
>> +
>> +static int mdev_uevent(struct device *dev, struct kobj_uevent_env *env)
>> +{
>> +	struct mdev_device *mdev = to_mdev_device(dev);
>> +
>> +	return add_uevent_var(env, "MODALIAS=mdev:c%02X", mdev->class_id);
>> +}
>> +
>>   struct bus_type mdev_bus_type = {
>>   	.name		= "mdev",
>> +	.match		= mdev_match,
>> +	.uevent		= mdev_uevent,
>>   	.probe		= mdev_probe,
>>   	.remove		= mdev_remove,
>>   };
>> diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
>> index 7d922950caaf..c65f436c1869 100644
>> --- a/drivers/vfio/mdev/mdev_private.h
>> +++ b/drivers/vfio/mdev/mdev_private.h
>> @@ -33,6 +33,7 @@ struct mdev_device {
>>   	struct kobject *type_kobj;
>>   	struct device *iommu_device;
>>   	bool active;
>> +	u16 class_id;
>>   };
>>   
>>   #define to_mdev_device(dev)	container_of(dev, struct mdev_device, dev)
>> diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
>> index 30964a4e0a28..7b24ee9cb8dd 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 const struct mdev_class_id id_table[] = {
>> +	{ MDEV_CLASS_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..78b69d09eb54 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)
>> @@ -132,6 +134,7 @@ struct mdev_driver {
>>   void *mdev_get_drvdata(struct mdev_device *mdev);
>>   void mdev_set_drvdata(struct mdev_device *mdev, void *data);
>>   const guid_t *mdev_uuid(struct mdev_device *mdev);
>> +void mdev_set_class(struct mdev_device *mdev, u16 id);
>>   
>>   extern struct bus_type mdev_bus_type;
>>   
>> @@ -145,4 +148,9 @@ 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);
>>   
>> +enum {
>> +	MDEV_CLASS_ID_VFIO = 1,
>> +	/* New entries must be added here */
>> +};
>> +
>>   #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..115bc5074656 100644
>> --- a/samples/vfio-mdev/mbochs.c
>> +++ b/samples/vfio-mdev/mbochs.c
>> @@ -561,6 +561,7 @@ static int mbochs_create(struct kobject *kobj, struct mdev_device *mdev)
>>   	mbochs_reset(mdev);
>>   
>>   	mbochs_used_mbytes += type->mbytes;
>> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>>   	return 0;
>>   
>>   err_mem:
>> diff --git a/samples/vfio-mdev/mdpy.c b/samples/vfio-mdev/mdpy.c
>> index cc86bf6566e4..665614574d50 100644
>> --- a/samples/vfio-mdev/mdpy.c
>> +++ b/samples/vfio-mdev/mdpy.c
>> @@ -269,6 +269,7 @@ static int mdpy_create(struct kobject *kobj, struct mdev_device *mdev)
>>   	mdpy_reset(mdev);
>>   
>>   	mdpy_count++;
>> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>>   	return 0;
>>   }
>>   
>> diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
>> index ce84a300a4da..90da12ff7fd9 100644
>> --- a/samples/vfio-mdev/mtty.c
>> +++ b/samples/vfio-mdev/mtty.c
>> @@ -755,6 +755,7 @@ static int mtty_create(struct kobject *kobj, struct mdev_device *mdev)
>>   	list_add(&mdev_state->next, &mdev_devices_list);
>>   	mutex_unlock(&mdev_list_lock);
>>   
>> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>>   	return 0;
>>   }
>>