RE: [PATCH v7 1/9] iommu: Add cache_invalidate_user op

Tian, Kevin
2023-12-22T02:30:43Z

> From: Liu, Yi L <yi.l.liu@intel.com>
> Sent: Thursday, December 21, 2023 11:40 PM
>
> From: Lu Baolu <baolu.lu@linux.intel.com>
>
> The updates of the PTEs in the nested page table will be propagated to the
> hardware caches on both IOMMU (IOTLB) and devices (DevTLB/ATC).

this is incorrect. the scope of this cmd is driver specific.

>
> Add a new domain op cache_invalidate_user for the userspace to flush the
> hardware caches for a nested domain through iommufd. No wrapper for it,
> as it's only supposed to be used by iommufd. Then, pass in invalidation
> requests in form of a user data array conatining a number of invalidation
> data entries.
>
> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
> Reviewed-by: Kevin Tian <kevin.tian@intel.com>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> ---
> include/linux/iommu.h | 27 +++++++++++++++++++++++++++
> 1 file changed, 27 insertions(+)
>
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 6291aa7b079b..5c4a17f13761 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -284,6 +284,24 @@ struct iommu_user_data {
> size_t len;
> };
>
> +/**
> + * struct iommu_user_data_array - iommu driver specific user space data
> array
> + * @type: The data type of all the entries in the user buffer array
> + * @uptr: Pointer to the user buffer array for copy_from_user()

remove 'for copy_from_user();

> + * @entry_len: The fixed-width length of a entry in the array, in bytes

s/a/an/

> + * @entry_num: The number of total entries in the array
> + *
> + * A array having a @entry_num number of @entry_len sized entries, each

the first sentence is redundant.

> entry is
> + * user space data, an uAPI defined in include/uapi/linux/iommufd.h where
> @type
> + * is also defined as enum iommu_xyz_data_type.

I'd just say:

"The user buffer includes an array of requests with format defined
in include/uapi/linux/iommufd.h"