> From: Nicolin Chen <nicolinc@xxxxxxxxxx> > Sent: Wednesday, September 11, 2024 3:31 PM > > On Wed, Sep 11, 2024 at 07:09:15AM +0000, Tian, Kevin wrote: > > > From: Nicolin Chen <nicolinc@xxxxxxxxxx> > > > Sent: Wednesday, September 11, 2024 4:41 AM > > > > > > -3. IOMMUFD_OBJ_HW_PAGETABLE is created when an external driver > calls > > > the IOMMUFD > > > +3. IOMMUFD_OBJ_HWPT_PAGING can be created in two ways: > > > + > > > + IOMMUFD_OBJ_HWPT_PAGING is created when an external driver > calls > > > the IOMMUFD > > > kAPI to attach a bound device to an IOAS. Similarly the external driver > uAPI > > > allows userspace to initiate the attaching operation. If a compatible > > > pagetable already exists then it is reused for the attachment. Otherwise > a > > > new pagetable object and iommu_domain is created. Successful > > > completion of > > > this operation sets up the linkages among IOAS, device and > > > iommu_domain. Once > > > - this completes the device could do DMA. > > > - > > > - Every iommu_domain inside the IOAS is also represented to userspace > as > > > a > > > - HW_PAGETABLE object. > > > + this completes the device could do DMA. Note that every > iommu_domain > > > inside > > > + the IOAS is also represented to userspace as an > > > IOMMUFD_OBJ_HWPT_PAGING. > > > > the last sentence is redundant. here we are talking about how > HWPT_PAGING > > is created so it's implied. probably you can state that HWPT_PAGING object > > is created when talking about "otherwise a new page table object and > > iommu_domain is created". > > I don't quite get this part...where is the redundancy? And where > is "otherwise a new page table object .."? the original text: allows userspace to initiate the attaching operation. If a compatible pagetable already exists then it is reused for the attachment. Otherwise a new pagetable object and iommu_domain is created. Successful completion of it's clear to say that HWPT_PAGING object is created upon successful completion there. Then naturally every iommu_domain in an IOAS is represented to userspace as HWPT_PAGING. Not added by you but could be cleaned up while at it. 😊
