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

Alex Williamson
2019-09-23T16:05:39Z

On Mon, 23 Sep 2019 21:03:26 +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,
> 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@redhat.com>
> ---
> 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.
> */
> 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);
>
> * 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);
>
> 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.
> *
> * 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)
> {
> 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;
>

I don't think we want to tie the class_id to the parent. mdev parent
devices can create various types of devices, some might be virtio, some
might be vfio. I think the cover letter even suggests that's a
direction these virtio devices might be headed. It seems the class
should be on the resulting device itself. That also suggests that at
the parent we cannot have a single device_ops, the ops used will depend
on the type of device created. Perhaps that means we need vfio_ops
alongside virtio_ops, rather than a common device_ops. Thanks,

Alex

> 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 */
> +
> #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..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;
>