On Thu, 6 Feb 2020 11:14:27 +0100 Auger Eric <[email protected]> wrote:
> Hi Jacob, > On 1/29/20 7:02 AM, Jacob Pan wrote: > > 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. > I would rather put the above justification in the commit msg and not > here. make sense. > > + * > > + * 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 > s/to to/to will fix. > > + * results in version bump up. > in a version number increment? sounds good, more specific. > > + * > > + * 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 */ > > > Thanks > > Eric > _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
