Re: [PATCH v7 3/4] iommufd: Add IOMMU_GET_HW_INFO

[Jason Gunthorpe]

On Fri, Aug 11, 2023 at 12:15:00AM -0700, Yi Liu wrote:
> Under nested IOMMU translation, userspace owns the stage-1 translation
> table (e.g. the stage-1 page table of Intel VT-d or the context table
> of ARM SMMUv3, and etc.). Stage-1 translation tables are vendor specific,
> and need to be compatible with the underlying IOMMU hardware. Hence,
> userspace should know the IOMMU hardware capability before creating and
> configuring the stage-1 translation table to kernel.
> 
> This adds IOMMU_GET_HW_INFO ioctl to query the IOMMU hardware information
> (a.k.a capability) for a given device. The returned data is vendor specific,
> userspace needs to decode it with the structure mapped by the @out_data_type
> field.
> 
> As only physical devices have IOMMU hardware, so this will return error
> if the given device is not a physical device.
> 
> Reviewed-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> Co-developed-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
> Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
> Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
> ---
>  drivers/iommu/iommufd/main.c | 85 ++++++++++++++++++++++++++++++++++++
>  include/uapi/linux/iommufd.h | 36 +++++++++++++++
>  2 files changed, 121 insertions(+)
> 
> diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
> index 94c498b8fdf6..d459811c5381 100644
> --- a/drivers/iommu/iommufd/main.c
> +++ b/drivers/iommu/iommufd/main.c
> @@ -17,6 +17,7 @@

I was looking at this more and this code should be in device.c:
  
> +static int iommufd_fill_hw_info(struct device *dev, void __user *user_ptr,
> +				unsigned int *length, u32 *type)
> +{

Since it is working on devices

main.c is primarily for context related stuff

Jason