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

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Date:   Tue, 15 Oct 2019 20:12:33 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Cornelia Huck <cohuck@...hat.com>
Cc:     kvm@...r.kernel.org, linux-s390@...r.kernel.org,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
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        xiao.w.wang@...el.com, haotian.wang@...ive.com,
        zhenyuw@...ux.intel.com, zhi.a.wang@...el.com,
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Subject: Re: [PATCH V3 1/7] mdev: class id support


On 2019/10/15 下午6:26, Cornelia Huck wrote:
> On Fri, 11 Oct 2019 16:15:51 +0800
> Jason Wang <jasowang@...hat.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@...hat.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);
> Should the document state explicitly that this should be done in the
> ->create() callback?


Yes, it's better.


> Also, I think that the class_id might be different
> for different mdevs (even if the parent is the same) -- should that be
> mentioned explicitly?


Yes, depends on the mdev_supported_type.

Thanks


>
>> +
>>   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
>>   ==================================================
>>   
> (...)
>
> Looks reasonable to me.