Re: [RFC PATCH 1/2] mdev: device id support

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On 2019/9/17 下午3:55, Tian, Kevin wrote:

From: Jason Wang
Sent: Thursday, September 12, 2019 5:40 PM

Mdev bus only support 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
id support in bus match method to pair the mdev device and mdev driver
correctly.

"device id" sound a bit confusing to me - it usually means something
unique to each device, while here it is used to indicate expected driver
types (vfio, virtio, etc.). but using "bus id" is also not good - we have
only one mdev bus here. Then what about "class id"?



I'm fine with this.

Thanks





So this patch add id_table to mdev_driver and id for mdev parent, and
implement the match method for mdev bus.

[1] https://lkml.org/lkml/2019/9/10/135

Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
---
  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              |  6 +++++-
  include/linux/mod_devicetable.h   |  6 ++++++
  samples/vfio-mdev/mbochs.c        |  2 +-
  samples/vfio-mdev/mdpy.c          |  2 +-
  samples/vfio-mdev/mtty.c          |  2 +-
  12 files changed, 51 insertions(+), 9 deletions(-)

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 5eb61116ca6f..f87d9409e290 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -578,7 +578,7 @@ 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 0604b49a4d32..eacbde3c7a97 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..fc07ff3ebe96 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 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->device_id = 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..fd5e9541d18e 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_device_id *ids = mdrv->id_table;
+
+	for (i = 0; ids[i].id; i++)
+		if (ids[i].id == mdev->parent->device_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..7fc8153671e0 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 device_id;
  };

  struct mdev_device {
diff --git a/drivers/vfio/mdev/vfio_mdev.c
b/drivers/vfio/mdev/vfio_mdev.c
index 30964a4e0a28..887c57f10880 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_device_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..f85045392120 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_device_id *id_table;
  };

  #define to_mdev_driver(drv)	container_of(drv, struct mdev_driver, driver)
@@ -135,7 +137,7 @@ 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 +147,6 @@ 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..f1fc143df042 100644
--- a/include/linux/mod_devicetable.h
+++ b/include/linux/mod_devicetable.h
@@ -821,4 +821,10 @@ struct wmi_device_id {
  	const void *context;
  };

+/* MDEV */
+
+struct mdev_device_id {
+	__u8 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;

--
2.19.1

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