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

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;