Re: [RFC PATCH 1/2] mdev: device id support

[Jason Wang <jasowang@redhat.com>]

On 2019/9/17 下午3:55, Tian, Kevin wrote:
>> From: Jason Wang
>> Sent: Thursday, September 12, 2019 5:40 PM
>>
>> Mdev bus only support 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
>> id support in bus match method to pair the mdev device and mdev driver
>> correctly.
> "device id" sound a bit confusing to me - it usually means something
> unique to each device, while here it is used to indicate expected driver
> types (vfio, virtio, etc.). but using "bus id" is also not good - we have
> only one mdev bus here. Then what about "class id"?


I'm fine with this.

Thanks


>
>> So this patch add id_table to mdev_driver and id for mdev parent, and
>> implement the match method for mdev bus.
>>
>> [1] https://lkml.org/lkml/2019/9/10/135
>>
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>> ---
>>   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              |  6 +++++-
>>   include/linux/mod_devicetable.h   |  6 ++++++
>>   samples/vfio-mdev/mbochs.c        |  2 +-
>>   samples/vfio-mdev/mdpy.c          |  2 +-
>>   samples/vfio-mdev/mtty.c          |  2 +-
>>   12 files changed, 51 insertions(+), 9 deletions(-)
>>
>> 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 5eb61116ca6f..f87d9409e290 100644
>> --- a/drivers/s390/cio/vfio_ccw_ops.c
>> +++ b/drivers/s390/cio/vfio_ccw_ops.c
>> @@ -578,7 +578,7 @@ 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 0604b49a4d32..eacbde3c7a97 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..fc07ff3ebe96 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 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->device_id = 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..fd5e9541d18e 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_device_id *ids = mdrv->id_table;
>> +
>> +	for (i = 0; ids[i].id; i++)
>> +		if (ids[i].id == mdev->parent->device_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..7fc8153671e0 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 device_id;
>>   };
>>
>>   struct mdev_device {
>> diff --git a/drivers/vfio/mdev/vfio_mdev.c
>> b/drivers/vfio/mdev/vfio_mdev.c
>> index 30964a4e0a28..887c57f10880 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_device_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..f85045392120 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_device_id *id_table;
>>   };
>>
>>   #define to_mdev_driver(drv)	container_of(drv, struct mdev_driver, driver)
>> @@ -135,7 +137,7 @@ 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 +147,6 @@ 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..f1fc143df042 100644
>> --- a/include/linux/mod_devicetable.h
>> +++ b/include/linux/mod_devicetable.h
>> @@ -821,4 +821,10 @@ struct wmi_device_id {
>>   	const void *context;
>>   };
>>
>> +/* MDEV */
>> +
>> +struct mdev_device_id {
>> +	__u8 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
>>
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