On Tue, 15 Oct 2019 20:17:01 +0800 Jason Wang jasowang@redhat.com wrote:
On 2019/10/15 下午6:41, Cornelia Huck wrote:
On Fri, 11 Oct 2019 16:15:54 +0800 Jason Wang jasowang@redhat.com wrote:
Currently, except for the create and remove, the rest of mdev_parent_ops is designed for vfio-mdev driver only and may not help for kernel mdev driver. With the help of class id, this patch introduces device specific callbacks inside mdev_device structure. This allows different set of callback to be used by vfio-mdev and virtio-mdev.
Signed-off-by: Jason Wang jasowang@redhat.com
.../driver-api/vfio-mediated-device.rst | 22 +++++--- MAINTAINERS | 1 + drivers/gpu/drm/i915/gvt/kvmgt.c | 18 ++++--- drivers/s390/cio/vfio_ccw_ops.c | 18 ++++--- drivers/s390/crypto/vfio_ap_ops.c | 14 +++-- drivers/vfio/mdev/mdev_core.c | 9 +++- drivers/vfio/mdev/mdev_private.h | 1 + drivers/vfio/mdev/vfio_mdev.c | 37 ++++++------- include/linux/mdev.h | 42 +++------------ include/linux/vfio_mdev.h | 52 +++++++++++++++++++ samples/vfio-mdev/mbochs.c | 20 ++++--- samples/vfio-mdev/mdpy.c | 21 +++++--- samples/vfio-mdev/mtty.c | 18 ++++--- 13 files changed, 177 insertions(+), 96 deletions(-) create mode 100644 include/linux/vfio_mdev.h
diff --git a/Documentation/driver-api/vfio-mediated-device.rst b/Documentation/driver-api/vfio-mediated-device.rst index 2035e48da7b2..553574ebba73 100644 --- a/Documentation/driver-api/vfio-mediated-device.rst +++ b/Documentation/driver-api/vfio-mediated-device.rst @@ -152,11 +152,20 @@ callbacks per mdev parent device, per mdev type, or any other categorization. Vendor drivers are expected to be fully asynchronous in this respect or provide their own internal resource protection.)
-The callbacks in the mdev_parent_ops structure are as follows: +In order to support multiple types of device/driver, device needs to +provide both class_id and device_ops through:
"As multiple types of mediated devices may be supported, the device needs to set up the class id and the device specific callbacks via:"
?
-* open: open callback of mediated device -* close: close callback of mediated device -* ioctl: ioctl callback of mediated device
- void mdev_set_class(struct mdev_device *mdev, u16 id, const void *ops);
+The class_id is used to be paired with ids in id_table in mdev_driver +structure for probing the correct driver.
"The class id (specified in id) is used to match a device with an mdev driver via its id table."
?
The device_ops is device +specific callbacks which can be get through mdev_get_dev_ops() +function by mdev bus driver.
"The device specific callbacks (specified in *ops) are obtainable via mdev_get_dev_ops() (for use by the mdev bus driver.)"
?
For vfio-mdev device, its device specific +ops are as follows:
"A vfio-mdev device (class id MDEV_ID_VFIO) uses the following device-specific ops:"
?
All you propose is better than what I wrote, will change the docs.
+* open: open callback of vfio mediated device +* close: close callback of vfio mediated device +* ioctl: ioctl callback of vfio mediated device
- read : read emulation callback
- write: write emulation callback
- mmap: mmap emulation callback
@@ -167,9 +176,10 @@ register itself with the mdev core driver:: extern int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops);
-It is also required to specify the class_id through:: +It is also required to specify the class_id and device specific ops through::
- extern int mdev_set_class(struct device *dev, u16 id);
- extern int mdev_set_class(struct device *dev, u16 id,
const void *ops);Apologies if that has already been discussed, but do we want a 1:1 relationship between id and ops, or can different devices with the same id register different ops?
I think we have a N:1 mapping between id and ops, e.g we want both virtio-mdev and vhost-mdev use a single set of device ops.
The contents of the ops structure is essentially defined by the id, which is why I was leaning towards them being defined together. They are effectively interlocked, the id defines which mdev "endpoint" driver is loaded and that driver requires mdev_get_dev_ops() to return the structure required by the driver. I wish there was a way we could incorporate type checking here. We toyed with the idea of having the class in the same structure as the ops, but I think this approach was chosen for simplicity. We could still do something like:
int mdev_set_class_struct(struct device *dev, const struct mdev_class_struct *class);
struct mdev_class_struct { u16 id; union { struct vfio_mdev_ops vfio_ops; struct virtio_mdev_ops virtio_ops; }; };
Maybe even:
struct vfio_mdev_ops *mdev_get_vfio_ops(struct mdev_device *mdev) { BUG_ON(mdev->class.id != MDEV_ID_VFIO); return &mdev->class.vfio_ops; }
The match callback would of course just use the mdev->class.id value. Functionally equivalent, but maybe better type characteristics. Thanks,
Alex