Re: [PATCH v2 03/22] iommufd/viommu: Allow driver-specific user data for a vIOMMU object

[Pranjal Shrivastava <praan@google.com>]

On Fri, Apr 25, 2025 at 10:57:58PM -0700, Nicolin Chen wrote:
> The new type of vIOMMU for tegra241-cmdqv driver needs a driver-specific
> user data. So, add data_len/uptr to the iommu_viommu_alloc uAPI and pass
> it in via the viommu_alloc iommu op.
> 
> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>

Acked-by: Pranjal Shrivastava <praan@google.com>

> ---
>  include/uapi/linux/iommufd.h   | 6 ++++++
>  drivers/iommu/iommufd/viommu.c | 8 +++++++-
>  2 files changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
> index f29b6c44655e..cc90299a08d9 100644
> --- a/include/uapi/linux/iommufd.h
> +++ b/include/uapi/linux/iommufd.h
> @@ -965,6 +965,9 @@ enum iommu_viommu_type {
>   * @dev_id: The device's physical IOMMU will be used to back the virtual IOMMU
>   * @hwpt_id: ID of a nesting parent HWPT to associate to
>   * @out_viommu_id: Output virtual IOMMU ID for the allocated object
> + * @data_len: Length of the type specific data
> + * @__reserved: Must be 0
> + * @data_uptr: User pointer to an array of driver-specific virtual IOMMU data
>   *
>   * Allocate a virtual IOMMU object, representing the underlying physical IOMMU's
>   * virtualization support that is a security-isolated slice of the real IOMMU HW
> @@ -985,6 +988,9 @@ struct iommu_viommu_alloc {
>  	__u32 dev_id;
>  	__u32 hwpt_id;
>  	__u32 out_viommu_id;
> +	__u32 data_len;
> +	__u32 __reserved;
> +	__aligned_u64 data_uptr;
>  };
>  #define IOMMU_VIOMMU_ALLOC _IO(IOMMUFD_TYPE, IOMMUFD_CMD_VIOMMU_ALLOC)
>  
> diff --git a/drivers/iommu/iommufd/viommu.c b/drivers/iommu/iommufd/viommu.c
> index fffa57063c60..a65153458a26 100644
> --- a/drivers/iommu/iommufd/viommu.c
> +++ b/drivers/iommu/iommufd/viommu.c
> @@ -17,6 +17,11 @@ void iommufd_viommu_destroy(struct iommufd_object *obj)
>  int iommufd_viommu_alloc_ioctl(struct iommufd_ucmd *ucmd)
>  {
>  	struct iommu_viommu_alloc *cmd = ucmd->cmd;
> +	const struct iommu_user_data user_data = {
> +		.type = cmd->type,
> +		.uptr = u64_to_user_ptr(cmd->data_uptr),
> +		.len = cmd->data_len,
> +	};
>  	struct iommufd_hwpt_paging *hwpt_paging;
>  	struct iommufd_viommu *viommu;
>  	struct iommufd_device *idev;
> @@ -48,7 +53,8 @@ int iommufd_viommu_alloc_ioctl(struct iommufd_ucmd *ucmd)
>  	}
>  
>  	viommu = ops->viommu_alloc(idev->dev, hwpt_paging->common.domain,
> -				   ucmd->ictx, cmd->type, NULL);
> +				   ucmd->ictx, cmd->type,
> +				   user_data.len ? &user_data : NULL);
>  	if (IS_ERR(viommu)) {
>  		rc = PTR_ERR(viommu);
>  		goto out_put_hwpt;
> -- 
> 2.43.0
>