Re: [PATCH V3 1/7] mdev: class id support

[Jason Wang <jasowang@redhat.com>]

On 2019/10/16 下午12:57, Parav Pandit wrote:
>
>> -----Original Message-----
>> From: Jason Wang <jasowang@redhat.com>
>> Sent: Friday, October 11, 2019 3:16 AM
>> To: kvm@vger.kernel.org; linux-s390@vger.kernel.org; linux-
>> kernel@vger.kernel.org; dri-devel@lists.freedesktop.org; intel-
>> gfx@lists.freedesktop.org; intel-gvt-dev@lists.freedesktop.org;
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>> lingshan.zhu@intel.com; Ido Shamay <idos@mellanox.com>;
>> eperezma@redhat.com; lulu@redhat.com; Parav Pandit
>> <parav@mellanox.com>; christophe.de.dinechin@gmail.com;
>> kevin.tian@intel.com; Jason Wang <jasowang@redhat.com>
>> Subject: [PATCH V3 1/7] mdev: class id support
>>
>> 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>
>> ---
>>   Documentation/driver-api/vfio-mediated-device.rst |  7 ++++++-
>>   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                     | 11 +++++++++++
>>   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                              |  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, 60 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/driver-api/vfio-mediated-device.rst
>> b/Documentation/driver-api/vfio-mediated-device.rst
>> index 25eb7d5b834b..2035e48da7b2 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 @@ -165,12 +167,15 @@ register itself with the mdev core driver::
>>   	extern int  mdev_register_device(struct device *dev,
>>   	                                 const struct mdev_parent_ops *ops);
>>
>> +It is also required to specify the class_id through::
>> +
>> +	extern int mdev_set_class(struct device *dev, u16 id);
> Drop extern.
> In actual API you have correct signature, i.e. struct mdev_device.
> s/struct device/struct mdev_device.


Yes, will fix.


>
>> +
>>   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::
>>
>>   	extern void mdev_unregister_device(struct device *dev);
>>
>> -
>>   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..17e9d4634c84 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_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..b5d223882c6c
>> 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_ID_VFIO);
>>   	return 0;
>>   }
>>
>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c
>> b/drivers/s390/crypto/vfio_ap_ops.c
>> index 5c0f53c6dde7..47df1c593c35 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_ID_VFIO);
>>   	return 0;
>>   }
>>
>> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
>> index b558d4cfd082..724e9b9841d8 100644
>> --- a/drivers/vfio/mdev/mdev_core.c
>> +++ b/drivers/vfio/mdev/mdev_core.c
>> @@ -45,6 +45,12 @@ void mdev_set_drvdata(struct mdev_device *mdev,
>> void *data)  }  EXPORT_SYMBOL(mdev_set_drvdata);
>>
>> +void mdev_set_class(struct mdev_device *mdev, u16 id) {
>> +	mdev->class_id = id;
>> +}
>> +EXPORT_SYMBOL(mdev_set_class);
>> +
> Usually with every exported symbol we have signature comment block that describes when to use an API etc.
> Please add it that describes that this API must be called during create() callback.


Ok.


>
>>   struct device *mdev_dev(struct mdev_device *mdev)  {
>>   	return &mdev->dev;
>> @@ -135,6 +141,7 @@ 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 +331,9 @@ int mdev_device_create(struct kobject *kobj,
>>   	if (ret)
>>   		goto ops_create_fail;
>>
>> +	if (!mdev->class_id)
>> +		goto class_id_fail;
>> +
>>   	ret = device_add(&mdev->dev);
>>   	if (ret)
>>   		goto add_fail;
>> @@ -340,6 +350,7 @@ int mdev_device_create(struct kobject *kobj,
>>
>>   sysfs_fail:
>>   	device_del(&mdev->dev);
>> +class_id_fail:
> No need for new label. Just use add_fail label.


Ok.


>
>>   add_fail:
>>   	parent->ops->remove(mdev);
>>   ops_create_fail:
>> diff --git a/drivers/vfio/mdev/mdev_driver.c
>> b/drivers/vfio/mdev/mdev_driver.c index 0d3223aee20b..b7c40ce86ee3
>> 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->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..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..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[] = {
> static const


Fixed.


>
>> +	{ MDEV_ID_VFIO },
> I guess you don't need extra braces for each entry.
> Since this enum represents MDEV class id, it better to name it as MDEV_CLASS_ID_VFIO.
> (Similar to  PCI_VENDOR_ID, PCI_DEVICE_ID)..


Will do.


>> +	{ 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..a7570cf13ba4 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 {
>> @@ -125,12 +126,14 @@ 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)
>>
>>   void *mdev_get_drvdata(struct mdev_device *mdev);  void
>> mdev_set_drvdata(struct mdev_device *mdev, void *data);
>> +void mdev_set_class(struct mdev_device *mdev, u16 id);
> Better to insert new API after mdev_uuid().


Ok.

Thanks


>
>>   const guid_t *mdev_uuid(struct mdev_device *mdev);
>>
>>   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_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..fd8491e58fe2 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_ID_VFIO);
>>   	return 0;
>>
>>   err_mem:
>> diff --git a/samples/vfio-mdev/mdpy.c b/samples/vfio-mdev/mdpy.c index
>> cc86bf6566e4..889472b06708 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_ID_VFIO);
>>   	return 0;
>>   }
>>
>> diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c index
>> ce84a300a4da..618810ca4331 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_ID_VFIO);
>>   	return 0;
>>   }
>>
>> --
>> 2.19.1