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

From: Tian, Kevin
Date: Tue Sep 17 2019 - 04:09:30 EST

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> 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...

>
> 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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> https://lists.linuxfoundation.org/mailman/listinfo/virtualization

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