On Tue, Oct 20, 2020 at 02:00:31PM +0000, Liu, Yi L wrote: > > From: Jason Gunthorpe <jgg@xxxxxxxxxx> > > Sent: Tuesday, October 20, 2020 9:55 PM > > > > On Tue, Oct 20, 2020 at 09:40:14AM +0000, Liu, Yi L wrote: > > > > > > See previous discussion with Kevin. If I understand correctly, you expect a > > shared > > > > L2 table if vDPA and VFIO device are using the same PASID. > > > > > > L2 table sharing is not mandatory. The mapping is the same, but no need to > > > assume L2 tables are shared. Especially for VFIO/vDPA devices. Even within > > > a passthru framework, like VFIO, if the attributes of backend IOMMU are not > > > the same, the L2 page table are not shared, but the mapping is the same. > > > > I think not being able to share the PASID shows exactly why this VFIO > > centric approach is bad. > > no, I didn't say PASID is not sharable. My point is sharing L2 page table is > not mandatory. IMHO a PASID should be 1:1 with a page table, what does it even mean to share a PASID but have different page tables? Jason
