> From: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Sent: Wednesday, October 26, 2022 2:12 AM
>
> +int iommufd_vfio_compat_ioas_id(struct iommufd_ctx *ictx, u32
> *out_ioas_id)
> +{
> + struct iommufd_ioas *ioas = NULL;
> + struct iommufd_ioas *out_ioas;
> +
> + ioas = iommufd_ioas_alloc(ictx);
> + if (IS_ERR(ioas))
> + return PTR_ERR(ioas);
I tried to find out where the auto-created compat_ioas is destroyed.
Is my understanding correct that nobody holds a long-term users
count on it then we expect it to be destroyed in iommufd release?
If yes, probably worth adding a comment to explain this behavior.
> +
> + case IOMMU_VFIO_IOAS_SET:
> + ioas = iommufd_get_ioas(ucmd, cmd->ioas_id);
> + if (IS_ERR(ioas))
> + return PTR_ERR(ioas);
> + xa_lock(&ucmd->ictx->objects);
> + ucmd->ictx->vfio_ioas = ioas;
> + xa_unlock(&ucmd->ictx->objects);
> + iommufd_put_object(&ioas->obj);
> + return 0;
disallow changing vfio_ioas when it's already in-use e.g. has
a list of hwpt attached?
