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

From: Jason Wang
Date: Tue Sep 24 2019 - 07:20:57 EST

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On 2019/9/24 äå4:58, Parav Pandit wrote:
> Hi Jason,
>
>> -----Original Message-----
>> From: Jason Wang <jasowang@xxxxxxxxxx>
>> Sent: Monday, September 23, 2019 8:03 AM
>> To: kvm@xxxxxxxxxxxxxxx; linux-s390@xxxxxxxxxxxxxxx; linux-
>> kernel@xxxxxxxxxxxxxxx; dri-devel@xxxxxxxxxxxxxxxxxxxxx; intel-
>> gfx@xxxxxxxxxxxxxxxxxxxxx; intel-gvt-dev@xxxxxxxxxxxxxxxxxxxxx;
>> kwankhede@xxxxxxxxxx; alex.williamson@xxxxxxxxxx; mst@xxxxxxxxxx;
>> tiwei.bie@xxxxxxxxx
>> Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx;
>> cohuck@xxxxxxxxxx; maxime.coquelin@xxxxxxxxxx;
>> cunming.liang@xxxxxxxxx; zhihong.wang@xxxxxxxxx;
>> rob.miller@xxxxxxxxxxxx; xiao.w.wang@xxxxxxxxx;
>> haotian.wang@xxxxxxxxxx; zhenyuw@xxxxxxxxxxxxxxx; zhi.a.wang@xxxxxxxxx;
>> jani.nikula@xxxxxxxxxxxxxxx; joonas.lahtinen@xxxxxxxxxxxxxxx;
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>> borntraeger@xxxxxxxxxx; akrowiak@xxxxxxxxxxxxx; freude@xxxxxxxxxxxxx;
>> lingshan.zhu@xxxxxxxxx; Ido Shamay <idos@xxxxxxxxxxxx>;
>> eperezma@xxxxxxxxxx; lulu@xxxxxxxxxx; Parav Pandit
>> <parav@xxxxxxxxxxxx>; Jason Wang <jasowang@xxxxxxxxxx>
>> Subject: [PATCH 1/6] 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, one example is
>> virtio-mdev[1] driver. 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 parent with
>> the match method for mdev bus.
>>
>> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
>> ---
>> Documentation/driver-api/vfio-mediated-device.rst | 7 +++++--
>> 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 | 7 ++++++-
>> include/linux/mod_devicetable.h | 8 ++++++++
>> samples/vfio-mdev/mbochs.c | 2 +-
>> samples/vfio-mdev/mdpy.c | 2 +-
>> samples/vfio-mdev/mtty.c | 2 +-
>> 13 files changed, 59 insertions(+), 11 deletions(-)
>>
>> diff --git a/Documentation/driver-api/vfio-mediated-device.rst
>> b/Documentation/driver-api/vfio-mediated-device.rst
>> index 25eb7d5b834b..0e052072e1d8 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.
> No full stop at the end.

Will fix this.

>
>> */
>> 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
>> @@ -116,7 +118,7 @@ to register and unregister itself with the core driver:
>> * Register::
>>
>> extern int mdev_register_driver(struct mdev_driver *drv,
>> - struct module *owner);
>> + struct module *owner);
>>
> Unrelated change in this patch.

Yes, will fix.

>
>> * Unregister::
>>
>> @@ -163,7 +165,8 @@ A driver should use the mdev_parent_ops structure in
>> the function call to register itself with the mdev core driver::
>>
>> extern int mdev_register_device(struct device *dev,
>> - const struct mdev_parent_ops *ops);
>> + const struct mdev_parent_ops *ops,
>> + u8 class_id);
>>
> Cover letter from Change-V2 says that it class_id changed from " use u16 instead u8 for class id"
> But it is still u8 here?

Right, let me fix it in v2.

>
>> 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::
>> 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
>> f0d71ab77c50..246ff0f80944 100644
>> --- a/drivers/s390/cio/vfio_ccw_ops.c
>> +++ b/drivers/s390/cio/vfio_ccw_ops.c
>> @@ -588,7 +588,7 @@ 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 5c0f53c6dde7..7487fc39d2c5 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..a02c256a3514 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.
>> *
> It device id here, but in below its class_id. Please make them uniform.

Yes, will fix.

>> * 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 class_id)
>> {
> u16 class_id?

Yes it is.

>
>> 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->class_id = class_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..b70bbebc9dd3 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->parent->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..e58b07c866b1 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 class_id;
>> };
>>
>> struct mdev_device {
>> 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[] = {
>> + { 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..3ebae310f599 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)
>> @@ -135,7 +137,8 @@ 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 +148,6 @@ 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 */
>> +
> Instead of define, please put them as enum
>
> enum mdev_class/device_id {
> MDEV_ID_VFIO = 1,
> /* New entries must be added here */
> };

Ok.

>
>> #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;
>> +};
> This is u16 as I guess you wanted as opposed to u8 in other places in patch.

Right.

Thanks

>> +
>> #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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