On Mon, 26 Apr 2021 17:00:04 -0300
Jason Gunthorpe <jgg@xxxxxxxxxx> wrote:
> This allows a mdev driver to opt out of using vfio_mdev.c, instead the
> driver will provide a 'struct mdev_driver' and register directly with the
> driver core.
>
> Much of mdev_parent_ops becomes unused in this mode:
> - create()/remove() are done via the mdev_driver probe()/remove()
> - mdev_attr_groups becomes mdev_driver driver.dev_groups
> - Wrapper function callbacks are replaced with the same ones from
> struct vfio_device_ops
>
> Following patches convert all the drivers.
>
> Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> ---
> drivers/vfio/mdev/mdev_core.c | 64 ++++++++++++++++++++++++++++-----
> drivers/vfio/mdev/mdev_driver.c | 17 ++++++++-
> include/linux/mdev.h | 3 ++
> 3 files changed, 75 insertions(+), 9 deletions(-)
>
(...)
> +/*
> + * mdev drivers can refuse to bind during probe(), in this case we want to fail
> + * the creation of the mdev all the way back to sysfs. This is a weird model
> + * that doesn't fit in the driver core well, nor does it seem to appear any
> + * place else in the kernel, so use a simple hack.
> + */
> +static int mdev_bind_driver(struct mdev_device *mdev)
> +{
> + struct mdev_driver *drv = mdev->type->parent->ops->device_driver;
> + int ret;
> +
> + if (!drv)
> + drv = &vfio_mdev_driver;
> +
> + while (1) {
> + device_lock(&mdev->dev);
> + if (mdev->dev.driver == &drv->driver) {
> + ret = 0;
> + goto out_unlock;
> + }
> + if (mdev->probe_err) {
> + ret = mdev->probe_err;
> + goto out_unlock;
> + }
> + device_unlock(&mdev->dev);
> + ret = device_attach(&mdev->dev);
> + if (ret)
> + return ret;
device_attach() can return 0 (no driver), 1 (bound), or -ENODEV (device
not registered). I would expect mdev_bind_driver() to return 0 in case
of success and !0 otherwise, and I think the calling code does so as
well?
> + mdev->probe_err = -EINVAL;
> + }
> + return 0;
> +
> +out_unlock:
> + device_unlock(&mdev->dev);
> + return ret;
> +}
> +
(...)
Rest of the patch looks good to me.
