On Thu, Feb 24 2022, Yishai Hadas <yishaih@xxxxxxxxxx> wrote:
> From: Jason Gunthorpe <jgg@xxxxxxxxxx>
>
> Invoke a new device op 'device_feature' to handle just the data array
> portion of the command. This lifts the ioctl validation to the core code
> and makes it simpler for either the core code, or layered drivers, to
> implement their own feature values.
>
> Provide vfio_check_feature() to consolidate checking the flags/etc against
> what the driver supports.
>
> Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@xxxxxxxxxx>
> Signed-off-by: Yishai Hadas <yishaih@xxxxxxxxxx>
> ---
> drivers/vfio/pci/vfio_pci.c | 1 +
> drivers/vfio/pci/vfio_pci_core.c | 94 +++++++++++++-------------------
> drivers/vfio/vfio.c | 46 ++++++++++++++--
> include/linux/vfio.h | 32 +++++++++++
> include/linux/vfio_pci_core.h | 2 +
> 5 files changed, 114 insertions(+), 61 deletions(-)
(...)
> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> index 76191d7abed1..ca69516f869d 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -55,6 +55,7 @@ struct vfio_device {
> * @match: Optional device name match callback (return: 0 for no-match, >0 for
> * match, -errno for abort (ex. match with insufficient or incorrect
> * additional args)
> + * @device_feature: Fill in the VFIO_DEVICE_FEATURE ioctl
> */
> struct vfio_device_ops {
> char *name;
> @@ -69,8 +70,39 @@ struct vfio_device_ops {
> int (*mmap)(struct vfio_device *vdev, struct vm_area_struct *vma);
> void (*request)(struct vfio_device *vdev, unsigned int count);
> int (*match)(struct vfio_device *vdev, char *buf);
> + int (*device_feature)(struct vfio_device *device, u32 flags,
> + void __user *arg, size_t argsz);
> };
Is the expectation that most drivers will eventually implement
->device_feature()? Well, they will have to if they want to support
migration; mostly asking because e.g. ->match() is explicitly marked as
"optional". As the only callback every driver implements seems to be
->ioctl() (if we also include the samples), "optional" or not does not
seem to be particularly relevant anyway.
Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
