On Fri, May 19, 2023 at 01:32:20PM -0700, Jacob Pan wrote: > PCIe Process address space ID (PASID) is used to tag DMA traffic, it > provides finer grained isolation than requester ID (RID). > > For each RID, 0 is as a special PASID for the legacy DMA (without > PASID), thus RID_PASID. This is universal across all architectures, > therefore warranted to be declared in the common header. > Noting that VT-d could support none-zero RID_PASID, but currently not > used. > > By having a common RID_PASID, we can avoid conflicts between different > use cases in the generic code. e.g. SVA and DMA API with PASIDs. > > Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx> > --- > v6: > - let SMMU code use the common RID_PASID macro > --- > .../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c | 2 +- > drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 10 ++++---- > drivers/iommu/intel/iommu.c | 24 +++++++++---------- > drivers/iommu/intel/pasid.c | 2 +- > drivers/iommu/intel/pasid.h | 1 - > include/linux/iommu.h | 1 + > 6 files changed, 20 insertions(+), 20 deletions(-) I tend to agree with Jean-Philippe's remarks on the name This is the "untagged" DMA for environments that have optional tags. Otherwise: Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx> Jason
