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

From: Alex Williamson
Date: Wed Oct 23 2019 - 17:42:26 EST

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On Wed, 23 Oct 2019 21:07:47 +0800
Jason Wang <jasowang@xxxxxxxxxx> 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@xxxxxxxxxx>
> ---
> .../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");

> + 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,

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;
> }
>

Next message: Alex Williamson: "Re: [PATCH V5 2/6] modpost: add support for mdev class id"
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In reply to: Parav Pandit: "RE: [PATCH V5 1/6] mdev: class id support"
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