On Wed, May 05, 2021 at 01:04:46PM -0700, Jacob Pan wrote: > > > For ARM, since the guest owns the per device PASID table. There is no > > > need to allocate PASIDs from the host nor the hypervisor. Without SWQ, > > > there is no need for global PASID/SSID either. So PASID being global > > > for ARM is for simplicity in case of host PASID/SSID. > > > > It isn't clear how ARM can support PASID and mdev but that is an > > unrelated issue.. > > > AFAIK, the current SMMU device assignment is per RID, since only one stage2 > page tables per RID, not per PASID. This is equivalent to the older VT-d > spec. prior to scalable mode. Yes that's right. Since SMMUv3 has a single level-2 page table per RID, it doesn't support assigning level-1 page tables to guests for mdevs (sub-VF devices). So no PASIDs for mdevs, which also means each guest has its own PASID space and the host doesn't track guest PASIDs. Thanks, Jean
