Define a unified UAPI version to be used for compatibility checks between user and kernel.
Signed-off-by: Liu Yi L <[email protected]> Signed-off-by: Jacob Pan <[email protected]> --- include/uapi/linux/iommu.h | 48 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h index fcafb6401430..65a26c2519ee 100644 --- a/include/uapi/linux/iommu.h +++ b/include/uapi/linux/iommu.h @@ -8,6 +8,54 @@ #include <linux/types.h> +/** + * Current version of the IOMMU user API. This is intended for query + * between user and kernel to determine compatible data structures. + * + * Having a single UAPI version to govern the user-kernel data structures + * makes compatibility check straightforward. On the contrary, supporting + * combinations of multiple versions of the data can be a nightmare. + * + * UAPI version can be bumped up with the following rules: + * 1. All data structures passed between user and kernel space share + * the same version number. i.e. any extension to to any structure + * results in version bump up. + * + * 2. Data structures are open to extension but closed to modification. + * New fields must be added at the end of each data structure with + * 64bit alignment. Flag bits can be added without size change but + * existing ones cannot be altered. + * + * 3. Versions are backward compatible. + * + * 4. Version to size lookup is supported by kernel internal API for each + * API function type. @version is mandatory for new data structures + * and must be at the beginning with type of __u32. + */ +#define IOMMU_UAPI_VERSION 1 +static inline int iommu_get_uapi_version(void) +{ + return IOMMU_UAPI_VERSION; +} + +/* + * Supported UAPI features that can be reported to user space. + * These types represent the capability available in the kernel. + * + * REVISIT: UAPI version also implies the capabilities. Should we + * report them explicitly? + */ +enum IOMMU_UAPI_DATA_TYPES { + IOMMU_UAPI_BIND_GPASID, + IOMMU_UAPI_CACHE_INVAL, + IOMMU_UAPI_PAGE_RESP, + NR_IOMMU_UAPI_TYPE, +}; + +#define IOMMU_UAPI_CAP_MASK ((1 << IOMMU_UAPI_BIND_GPASID) | \ + (1 << IOMMU_UAPI_CACHE_INVAL) | \ + (1 << IOMMU_UAPI_PAGE_RESP)) + #define IOMMU_FAULT_PERM_READ (1 << 0) /* read */ #define IOMMU_FAULT_PERM_WRITE (1 << 1) /* write */ #define IOMMU_FAULT_PERM_EXEC (1 << 2) /* exec */ -- 2.7.4 _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
