Re: [PATCH 1/6] iommu: Add new iommu op to get iommu hardware information

[Binbin Wu <binbin.wu@linux.intel.com>]

On 2/9/2023 12:16 PM, Yi Liu wrote:
> From: Lu Baolu <baolu.lu@linux.intel.com>
>
> Introduce a new iommu op get

get -> to get


> the IOMMU hardware capabilities for iommufd.
> This information will be used by any vIOMMU driver which is owned by
> userspace.
>
> This op chooses to make the special parameters opaque to the core. This
> suits the current usage model where accessing any of the IOMMU device
> special parameters does require a userspace driver that matches the kernel
> driver. If a need for common parameters, implemented similarly by several
> drivers, arises then there is room in the design to grow a generic parameter
> set as well. No warpper

warpper -> wrapper


>   API is added as it is supposed to be used by
> iommufd only.
>
> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> ---
>   include/linux/iommu.h        | 8 ++++++++
>   include/uapi/linux/iommufd.h | 6 ++++++
>   2 files changed, 14 insertions(+)
>
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index cb586d054c57..97b398d19fd2 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -15,6 +15,7 @@
>   #include <linux/of.h>
>   #include <linux/ioasid.h>
>   #include <uapi/linux/iommu.h>
> +#include <uapi/linux/iommufd.h>
>   
>   #define IOMMU_READ	(1 << 0)
>   #define IOMMU_WRITE	(1 << 1)
> @@ -223,6 +224,11 @@ struct iommu_iotlb_gather {
>   /**
>    * struct iommu_ops - iommu ops and capabilities
>    * @capable: check capability
> + * @hw_info: IOMMU hardware capabilities. The type of the returned data is
> + *           defined in include/uapi/linux/iommufd.h. The data buffer is
> + *           allocated in the IOMMU driver and the caller should free it
> + *           after use. Return the data buffer if success, or ERR_PTR on
> + *	      failure.
>    * @domain_alloc: allocate iommu domain
>    * @probe_device: Add device to iommu driver handling
>    * @release_device: Remove device from iommu driver handling
> @@ -252,6 +258,7 @@ struct iommu_iotlb_gather {
>    */
>   struct iommu_ops {
>   	bool (*capable)(struct device *dev, enum iommu_cap);
> +	void *(*hw_info)(struct device *dev, u32 *length);
>   
>   	/* Domain allocation and freeing by the iommu driver */
>   	struct iommu_domain *(*domain_alloc)(unsigned iommu_domain_type);
> @@ -280,6 +287,7 @@ struct iommu_ops {
>   	void (*remove_dev_pasid)(struct device *dev, ioasid_t pasid);
>   
>   	const struct iommu_domain_ops *default_domain_ops;
> +	enum iommu_device_data_type driver_type;


How to understand the name "iommu_device_data_type"?
Is it just refer to the driver types or it has a more generic meaning?


>   	unsigned long pgsize_bitmap;
>   	struct module *owner;
>   };
> diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
> index 98ebba80cfa1..2309edb55028 100644
> --- a/include/uapi/linux/iommufd.h
> +++ b/include/uapi/linux/iommufd.h
> @@ -344,4 +344,10 @@ struct iommu_vfio_ioas {
>   	__u16 __reserved;
>   };
>   #define IOMMU_VFIO_IOAS _IO(IOMMUFD_TYPE, IOMMUFD_CMD_VFIO_IOAS)
> +
> +/**
> + * enum iommu_device_data_type - IOMMU hardware Data types
> + */
> +enum iommu_device_data_type {
> +};
>   #endif