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

Jason Wang
2019-10-24T03:27:36Z

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;
>> }
>>