Re: [PATCH v6 17/25] iommufd: Allow an input data_type via iommu_hw_info

[Jason Gunthorpe]

On Sat, Jun 14, 2025 at 12:14:42AM -0700, Nicolin Chen wrote:
> The iommu_hw_info can output via the out_data_type field the vendor data
> type from a driver, but this only allows driver to report one data type.
> 
> Now, with SMMUv3 having a Tegra241 CMDQV implementation, it has two sets
> of types and data structs to report.
> 
> One way to support that is to use the same type field bidirectionally.
> 
> Reuse the same field by adding an "in_data_type", allowing user space to
> request for a specific type and to get the corresponding data.
> 
> For backward compatibility, since the ioctl handler has never checked an
> input value, add an IOMMU_HW_INFO_FLAG_INPUT_TYPE to switch between the
> old output-only field and the new bidirectional field.
> 
> Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
> ---
>  include/uapi/linux/iommufd.h   | 20 +++++++++++++++++++-
>  drivers/iommu/iommufd/device.c |  9 ++++++---
>  2 files changed, 25 insertions(+), 4 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>

Jason