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

[Jason Wang <jasowang@xxxxxxxxxx>]

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
> >
> > _______________________________________________
> > Virtualization mailing list
> > Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
> > https://lists.linuxfoundation.org/mailman/listinfo/virtualization
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