On Tue, 17 Jan 2023 05:49:38 -0800
Yi Liu <yi.l.liu@xxxxxxxxx> wrote:
> This prepares to add ioctls for device cdev fd. This infrastructure includes:
> - add vfio_iommufd_attach() to support iommufd pgtable attach after
> bind_iommufd. A NULL pt_id indicates detach.
> - let vfio_iommufd_bind() to accept pt_id, e.g. the comapt_ioas_id in the
> legacy group path, and also return back dev_id if caller requires it.
>
> Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
> ---
> drivers/vfio/group.c | 12 +++++-
> drivers/vfio/iommufd.c | 79 ++++++++++++++++++++++++++++++----------
> drivers/vfio/vfio.h | 15 ++++++--
> drivers/vfio/vfio_main.c | 10 +++--
> 4 files changed, 88 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/vfio/group.c b/drivers/vfio/group.c
> index 7200304663e5..9484bb1c54a9 100644
> --- a/drivers/vfio/group.c
> +++ b/drivers/vfio/group.c
> @@ -157,6 +157,8 @@ static int vfio_group_ioctl_set_container(struct vfio_group *group,
> static int vfio_device_group_open(struct vfio_device_file *df)
> {
> struct vfio_device *device = df->device;
> + u32 ioas_id;
> + u32 *pt_id = NULL;
> int ret;
>
> mutex_lock(&device->group->group_lock);
> @@ -165,6 +167,14 @@ static int vfio_device_group_open(struct vfio_device_file *df)
> goto err_unlock_group;
> }
>
> + if (device->group->iommufd) {
> + ret = iommufd_vfio_compat_ioas_id(device->group->iommufd,
> + &ioas_id);
> + if (ret)
> + goto err_unlock_group;
> + pt_id = &ioas_id;
> + }
> +
> mutex_lock(&device->dev_set->lock);
> /*
> * Here we pass the KVM pointer with the group under the lock. If the
> @@ -174,7 +184,7 @@ static int vfio_device_group_open(struct vfio_device_file *df)
> df->kvm = device->group->kvm;
> df->iommufd = device->group->iommufd;
>
> - ret = vfio_device_open(df);
> + ret = vfio_device_open(df, NULL, pt_id);
> if (ret)
> goto err_unlock_device;
> mutex_unlock(&device->dev_set->lock);
> diff --git a/drivers/vfio/iommufd.c b/drivers/vfio/iommufd.c
> index 4f82a6fa7c6c..412644fdbf16 100644
> --- a/drivers/vfio/iommufd.c
> +++ b/drivers/vfio/iommufd.c
> @@ -10,9 +10,17 @@
> MODULE_IMPORT_NS(IOMMUFD);
> MODULE_IMPORT_NS(IOMMUFD_VFIO);
>
> -int vfio_iommufd_bind(struct vfio_device *vdev, struct iommufd_ctx *ictx)
> +/* @pt_id == NULL implies detach */
> +int vfio_iommufd_attach(struct vfio_device *vdev, u32 *pt_id)
> +{
> + lockdep_assert_held(&vdev->dev_set->lock);
> +
> + return vdev->ops->attach_ioas(vdev, pt_id);
> +}
I find this patch pretty confusing, I think it's rooted in all these
multiplexed interfaces, which extend all the way out to userspace with
a magic, reserved page table ID to detach a device from an IOAS. It
seems like it would be simpler to make a 'detach' API, a detach_ioas
callback on the vfio_device_ops, and certainly not an
vfio_iommufd_attach() function that does a detach provided the correct
args while also introducing a __vfio_iommufd_detach() function.
This series is also missing an update to
Documentation/driver-api/vfio.rst, which is already behind relative to
the iommufd interfaces. Thanks,
Alex
