Re: [PATCH v6 1/6] iommu: Add cache_invalidate_user op

On Fri, Nov 17, 2023 at 05:07:12AM -0800, Yi Liu wrote:

+/**

• • 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()
• • @entry_len: The fixed-width length of a entry in the array, in bytes
• • @entry_num: The number of total entries in the array
• • A array having a @entry_num number of @entry_len sized entries, each 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.
• */

+struct iommu_user_data_array {

• unsigned int type;
• void __user *uptr;
• size_t entry_len;
• int entry_num;

These are u32 in the uapi, they should probably be u32 here too. Otherwise we have to worry about truncation.

@@ -465,6 +492,9 @@ struct iommu_domain_ops { size_t size); void (*iotlb_sync)(struct iommu_domain *domain, struct iommu_iotlb_gather *iotlb_gather);

• int (*cache_invalidate_user)(struct iommu_domain *domain,

• 		     struct iommu_user_data_array *array,
  

• 		     u32 *error_code);
  

Regarding the other conversation I worry a u32 error_code is too small.

Unfortunately there is no obvious place to put something better so if we reach it we will have to add more error_code space via normal extension.

Maybe expand this to u64? That is 64 bits of error register data and the consumer index. It should do for SMMUv3 at least?

Jason