Re: [RFC PATCH 2/2] mdev: introduce device specific ops

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On 2019/9/17 下午4:09, Tian, Kevin wrote:

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

Currently, except for the crate and remove. The rest fields of
mdev_parent_ops is just designed for vfio-mdev driver and may not help
for kernel mdev driver. So follow the device id support by previous
patch, this patch introduces device specific ops which points to
device specific ops (e.g vfio ops). This allows the future drivers
like virtio-mdev to implement its own device specific ops.

Can you give an example about what ops might be required to support
kernel mdev driver? I know you posted a link earlier, but putting a small
example here can save time and avoid inconsistent understanding. Then
it will help whether the proposed split makes sense or there is a
possibility of redefining the callbacks to meet the both requirements.
imo those callbacks fulfill some basic requirements when mediating
a device...



I put it in the cover letter.
The link is https://lkml.org/lkml/2019/9/10/135 which abuses the current VFIO based mdev parent ops. 

Thanks



Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
---
  drivers/gpu/drm/i915/gvt/kvmgt.c  | 14 +++---
  drivers/s390/cio/vfio_ccw_ops.c   | 14 +++---
  drivers/s390/crypto/vfio_ap_ops.c | 10 +++--
  drivers/vfio/mdev/vfio_mdev.c     | 30 +++++++------
  include/linux/mdev.h              | 72 ++++++++++++++++++-------------
  samples/vfio-mdev/mbochs.c        | 16 ++++---
  samples/vfio-mdev/mdpy.c          | 16 ++++---
  samples/vfio-mdev/mtty.c          | 14 +++---
  8 files changed, 113 insertions(+), 73 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c
b/drivers/gpu/drm/i915/gvt/kvmgt.c
index 19d51a35f019..64823998fd58 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -1600,20 +1600,22 @@ static const struct attribute_group
*intel_vgpu_groups[] = {
  	NULL,
  };

-static struct mdev_parent_ops intel_vgpu_ops = {
-	.mdev_attr_groups       = intel_vgpu_groups,
-	.create			= intel_vgpu_create,
-	.remove			= intel_vgpu_remove,
-
+static struct vfio_mdev_parent_ops intel_vfio_vgpu_ops = {
  	.open			= intel_vgpu_open,
  	.release		= intel_vgpu_release,
-
  	.read			= intel_vgpu_read,
  	.write			= intel_vgpu_write,
  	.mmap			= intel_vgpu_mmap,
  	.ioctl			= intel_vgpu_ioctl,
  };

+static struct mdev_parent_ops intel_vgpu_ops = {
+	.mdev_attr_groups       = intel_vgpu_groups,
+	.create			= intel_vgpu_create,
+	.remove			= intel_vgpu_remove,
+	.device_ops	        = &intel_vfio_vgpu_ops,
+};
+
  static int kvmgt_host_init(struct device *dev, void *gvt, const void *ops)
  {
  	struct attribute **kvm_type_attrs;
diff --git a/drivers/s390/cio/vfio_ccw_ops.c
b/drivers/s390/cio/vfio_ccw_ops.c
index f87d9409e290..96e9f18100ae 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -564,11 +564,7 @@ static ssize_t vfio_ccw_mdev_ioctl(struct
mdev_device *mdev,
  	}
  }

-static const struct mdev_parent_ops vfio_ccw_mdev_ops = {
-	.owner			= THIS_MODULE,
-	.supported_type_groups  = mdev_type_groups,
-	.create			= vfio_ccw_mdev_create,
-	.remove			= vfio_ccw_mdev_remove,
+static const struct vfio_mdev_parent_ops vfio_mdev_ops = {
  	.open			= vfio_ccw_mdev_open,
  	.release		= vfio_ccw_mdev_release,
  	.read			= vfio_ccw_mdev_read,
@@ -576,6 +572,14 @@ static const struct mdev_parent_ops
vfio_ccw_mdev_ops = {
  	.ioctl			= vfio_ccw_mdev_ioctl,
  };

+static const struct mdev_parent_ops vfio_ccw_mdev_ops = {
+	.owner			= THIS_MODULE,
+	.supported_type_groups  = mdev_type_groups,
+	.create			= vfio_ccw_mdev_create,
+	.remove			= vfio_ccw_mdev_remove,
+	.device_ops		= &vfio_mdev_ops,
+};
+
  int vfio_ccw_mdev_reg(struct subchannel *sch)
  {
  	return mdev_register_vfio_device(&sch->dev,
&vfio_ccw_mdev_ops);
diff --git a/drivers/s390/crypto/vfio_ap_ops.c
b/drivers/s390/crypto/vfio_ap_ops.c
index eacbde3c7a97..a48282bff066 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -1280,15 +1280,19 @@ static ssize_t vfio_ap_mdev_ioctl(struct
mdev_device *mdev,
  	return ret;
  }

+static const struct vfio_mdev_parent_ops vfio_mdev_ops = {
+	.open			= vfio_ap_mdev_open,
+	.release		= vfio_ap_mdev_release,
+	.ioctl			= vfio_ap_mdev_ioctl,
+};
+
  static const struct mdev_parent_ops vfio_ap_matrix_ops = {
  	.owner			= THIS_MODULE,
  	.supported_type_groups	= vfio_ap_mdev_type_groups,
  	.mdev_attr_groups	= vfio_ap_mdev_attr_groups,
  	.create			= vfio_ap_mdev_create,
  	.remove			= vfio_ap_mdev_remove,
-	.open			= vfio_ap_mdev_open,
-	.release		= vfio_ap_mdev_release,
-	.ioctl			= vfio_ap_mdev_ioctl,
+	.device_ops		= &vfio_mdev_ops,
  };

  int vfio_ap_mdev_register(void)
diff --git a/drivers/vfio/mdev/vfio_mdev.c
b/drivers/vfio/mdev/vfio_mdev.c
index 887c57f10880..1196fbb6c3d2 100644
--- a/drivers/vfio/mdev/vfio_mdev.c
+++ b/drivers/vfio/mdev/vfio_mdev.c
@@ -25,15 +25,16 @@ static int vfio_mdev_open(void *device_data)
  {
  	struct mdev_device *mdev = device_data;
  	struct mdev_parent *parent = mdev->parent;
+	const struct vfio_mdev_parent_ops *ops = parent->ops-

device_ops;

  	int ret;

-	if (unlikely(!parent->ops->open))
+	if (unlikely(!ops->open))
  		return -EINVAL;

  	if (!try_module_get(THIS_MODULE))
  		return -ENODEV;

-	ret = parent->ops->open(mdev);
+	ret = ops->open(mdev);
  	if (ret)
  		module_put(THIS_MODULE);

@@ -44,9 +45,10 @@ static void vfio_mdev_release(void *device_data)
  {
  	struct mdev_device *mdev = device_data;
  	struct mdev_parent *parent = mdev->parent;
+	const struct vfio_mdev_parent_ops *ops = parent->ops-

device_ops;

-	if (likely(parent->ops->release))
-		parent->ops->release(mdev);
+	if (likely(ops->release))
+		ops->release(mdev);

  	module_put(THIS_MODULE);
  }
@@ -56,11 +58,12 @@ static long vfio_mdev_unlocked_ioctl(void
*device_data,
  {
  	struct mdev_device *mdev = device_data;
  	struct mdev_parent *parent = mdev->parent;
+	const struct vfio_mdev_parent_ops *ops = parent->ops-

device_ops;

-	if (unlikely(!parent->ops->ioctl))
+	if (unlikely(!ops->ioctl))
  		return -EINVAL;

-	return parent->ops->ioctl(mdev, cmd, arg);
+	return ops->ioctl(mdev, cmd, arg);
  }

  static ssize_t vfio_mdev_read(void *device_data, char __user *buf,
@@ -68,11 +71,12 @@ static ssize_t vfio_mdev_read(void *device_data,
char __user *buf,
  {
  	struct mdev_device *mdev = device_data;
  	struct mdev_parent *parent = mdev->parent;
+	const struct vfio_mdev_parent_ops *ops = parent->ops-

device_ops;

-	if (unlikely(!parent->ops->read))
+	if (unlikely(!ops->read))
  		return -EINVAL;

-	return parent->ops->read(mdev, buf, count, ppos);
+	return ops->read(mdev, buf, count, ppos);
  }

  static ssize_t vfio_mdev_write(void *device_data, const char __user *buf,
@@ -80,22 +84,24 @@ static ssize_t vfio_mdev_write(void *device_data,
const char __user *buf,
  {
  	struct mdev_device *mdev = device_data;
  	struct mdev_parent *parent = mdev->parent;
+	const struct vfio_mdev_parent_ops *ops = parent->ops-

device_ops;

-	if (unlikely(!parent->ops->write))
+	if (unlikely(!ops->write))
  		return -EINVAL;

-	return parent->ops->write(mdev, buf, count, ppos);
+	return ops->write(mdev, buf, count, ppos);
  }

  static int vfio_mdev_mmap(void *device_data, struct vm_area_struct
*vma)
  {
  	struct mdev_device *mdev = device_data;
  	struct mdev_parent *parent = mdev->parent;
+	const struct vfio_mdev_parent_ops *ops = parent->ops-

device_ops;

-	if (unlikely(!parent->ops->mmap))
+	if (unlikely(!ops->mmap))
  		return -EINVAL;

-	return parent->ops->mmap(mdev, vma);
+	return ops->mmap(mdev, vma);
  }

  static const struct vfio_device_ops vfio_mdev_dev_ops = {
diff --git a/include/linux/mdev.h b/include/linux/mdev.h
index f85045392120..3b8a76bc69cf 100644
--- a/include/linux/mdev.h
+++ b/include/linux/mdev.h
@@ -27,27 +27,9 @@ int mdev_set_iommu_device(struct device *dev,
struct device *iommu_device);
  struct device *mdev_get_iommu_device(struct device *dev);

  /**
- * struct mdev_parent_ops - Structure to be registered for each parent
device to
- * register the device to mdev module.
+ * struct vfio_mdev_parent_ops - Structure to be registered for each
+ * parent device to register the device to vfio-mdev module.
   *
- * @owner:		The module owner.
- * @dev_attr_groups:	Attributes of the parent device.
- * @mdev_attr_groups:	Attributes of the mediated device.
- * @supported_type_groups: Attributes to define supported types. It is
mandatory
- *			to provide supported types.
- * @create:		Called to allocate basic resources in parent device's
- *			driver for a particular mediated device. It is
- *			mandatory to provide create ops.
- *			@kobj: kobject of type for which 'create' is called.
- *			@mdev: mdev_device structure on of mediated
device
- *			      that is being created
- *			Returns integer: success (0) or error (< 0)
- * @remove:		Called to free resources in parent device's driver for
a
- *			a mediated device. It is mandatory to provide
'remove'
- *			ops.
- *			@mdev: mdev_device device structure which is
being
- *			       destroyed
- *			Returns integer: success (0) or error (< 0)
   * @open:		Open mediated device.
   *			@mdev: mediated device.
   *			Returns integer: success (0) or error (< 0)
@@ -72,6 +54,43 @@ struct device *mdev_get_iommu_device(struct
device *dev);
   * @mmap:		mmap callback
   *			@mdev: mediated device structure
   *			@vma: vma structure
+ */
+struct vfio_mdev_parent_ops {
+	int     (*open)(struct mdev_device *mdev);
+	void    (*release)(struct mdev_device *mdev);
+	ssize_t (*read)(struct mdev_device *mdev, char __user *buf,
+			size_t count, loff_t *ppos);
+	ssize_t (*write)(struct mdev_device *mdev, const char __user *buf,
+			 size_t count, loff_t *ppos);
+	long	(*ioctl)(struct mdev_device *mdev, unsigned int cmd,
+			 unsigned long arg);
+	int	(*mmap)(struct mdev_device *mdev, struct vm_area_struct
*vma);
+};
+
+/**
+ * struct mdev_parent_ops - Structure to be registered for each parent
device to
+ * register the device to mdev module.
+ *
+ * @owner:		The module owner.
+ * @dev_attr_groups:	Attributes of the parent device.
+ * @mdev_attr_groups:	Attributes of the mediated device.
+ * @supported_type_groups: Attributes to define supported types. It is
mandatory
+ *			to provide supported types.
+ * @create:		Called to allocate basic resources in parent device's
+ *			driver for a particular mediated device. It is
+ *			mandatory to provide create ops.
+ *			@kobj: kobject of type for which 'create' is called.
+ *			@mdev: mdev_device structure on of mediated
device
+ *			      that is being created
+ *			Returns integer: success (0) or error (< 0)
+ * @remove:		Called to free resources in parent device's driver for
a
+ *			a mediated device. It is mandatory to provide
'remove'
+ *			ops.
+ *			@mdev: mdev_device device structure which is
being
+ *			       destroyed
+ *			Returns integer: success (0) or error (< 0)
+ * @device_ops:         Device specific emulation callback.
+ *
   * Parent device that support mediated device should be registered with
mdev
   * module with mdev_parent_ops structure.
   **/
@@ -83,15 +102,7 @@ struct mdev_parent_ops {

  	int     (*create)(struct kobject *kobj, struct mdev_device *mdev);
  	int     (*remove)(struct mdev_device *mdev);
-	int     (*open)(struct mdev_device *mdev);
-	void    (*release)(struct mdev_device *mdev);
-	ssize_t (*read)(struct mdev_device *mdev, char __user *buf,
-			size_t count, loff_t *ppos);
-	ssize_t (*write)(struct mdev_device *mdev, const char __user *buf,
-			 size_t count, loff_t *ppos);
-	long	(*ioctl)(struct mdev_device *mdev, unsigned int cmd,
-			 unsigned long arg);
-	int	(*mmap)(struct mdev_device *mdev, struct vm_area_struct
*vma);
+	const void *device_ops;
  };

  /* interface for exporting mdev supported type attributes */
@@ -137,7 +148,8 @@ const guid_t *mdev_uuid(struct mdev_device
*mdev);

  extern struct bus_type mdev_bus_type;

-int mdev_register_vfio_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);
diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c
index 71a4469be85d..53ceb357f152 100644
--- a/samples/vfio-mdev/mbochs.c
+++ b/samples/vfio-mdev/mbochs.c
@@ -1418,12 +1418,7 @@ static struct attribute_group
*mdev_type_groups[] = {
  	NULL,
  };

-static const struct mdev_parent_ops mdev_fops = {
-	.owner			= THIS_MODULE,
-	.mdev_attr_groups	= mdev_dev_groups,
-	.supported_type_groups	= mdev_type_groups,
-	.create			= mbochs_create,
-	.remove			= mbochs_remove,
+static const struct vfio_mdev_parent_ops vfio_mdev_ops = {
  	.open			= mbochs_open,
  	.release		= mbochs_close,
  	.read			= mbochs_read,
@@ -1432,6 +1427,15 @@ static const struct mdev_parent_ops mdev_fops
= {
  	.mmap			= mbochs_mmap,
  };

+static const struct mdev_parent_ops mdev_fops = {
+	.owner			= THIS_MODULE,
+	.mdev_attr_groups	= mdev_dev_groups,
+	.supported_type_groups	= mdev_type_groups,
+	.create			= mbochs_create,
+	.remove			= mbochs_remove,
+	.device_ops		= &vfio_mdev_ops,
+};
+
  static const struct file_operations vd_fops = {
  	.owner		= THIS_MODULE,
  };
diff --git a/samples/vfio-mdev/mdpy.c b/samples/vfio-mdev/mdpy.c
index d3029dd27d91..4ba285a5768f 100644
--- a/samples/vfio-mdev/mdpy.c
+++ b/samples/vfio-mdev/mdpy.c
@@ -725,12 +725,7 @@ static struct attribute_group *mdev_type_groups[]
= {
  	NULL,
  };

-static const struct mdev_parent_ops mdev_fops = {
-	.owner			= THIS_MODULE,
-	.mdev_attr_groups	= mdev_dev_groups,
-	.supported_type_groups	= mdev_type_groups,
-	.create			= mdpy_create,
-	.remove			= mdpy_remove,
+static const struct vfio_mdev_parent_ops vfio_mdev_ops = {
  	.open			= mdpy_open,
  	.release		= mdpy_close,
  	.read			= mdpy_read,
@@ -739,6 +734,15 @@ static const struct mdev_parent_ops mdev_fops =
{
  	.mmap			= mdpy_mmap,
  };

+static const struct mdev_parent_ops mdev_fops = {
+	.owner			= THIS_MODULE,
+	.mdev_attr_groups	= mdev_dev_groups,
+	.supported_type_groups	= mdev_type_groups,
+	.create			= mdpy_create,
+	.remove			= mdpy_remove,
+	.device_ops		= &vfio_mdev_ops,
+};
+
  static const struct file_operations vd_fops = {
  	.owner		= THIS_MODULE,
  };
diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
index 744c88a6b22c..a468904ec626 100644
--- a/samples/vfio-mdev/mtty.c
+++ b/samples/vfio-mdev/mtty.c
@@ -1410,6 +1410,14 @@ static struct attribute_group
*mdev_type_groups[] = {
  	NULL,
  };

+static const struct vfio_mdev_parent_ops vfio_mdev_ops = {
+	.open                   = mtty_open,
+	.release                = mtty_close,
+	.read                   = mtty_read,
+	.write                  = mtty_write,
+	.ioctl		        = mtty_ioctl,
+};
+
  static const struct mdev_parent_ops mdev_fops = {
  	.owner                  = THIS_MODULE,
  	.dev_attr_groups        = mtty_dev_groups,
@@ -1417,11 +1425,7 @@ static const struct mdev_parent_ops mdev_fops
= {
  	.supported_type_groups  = mdev_type_groups,
  	.create                 = mtty_create,
  	.remove			= mtty_remove,
-	.open                   = mtty_open,
-	.release                = mtty_close,
-	.read                   = mtty_read,
-	.write                  = mtty_write,
-	.ioctl		        = mtty_ioctl,
+	.device_ops             = &vfio_mdev_ops,
  };

  static void mtty_device_release(struct device *dev)
--
2.19.1

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