On Fri, May 24, 2024 at 02:16:34AM +0000, Tian, Kevin wrote: > > From: Jason Gunthorpe <jgg@xxxxxxxxxx> > > Sent: Thursday, May 23, 2024 8:59 PM > > On Thu, May 23, 2024 at 01:43:45AM +0000, Tian, Kevin wrote: > > > > From: Jason Gunthorpe <jgg@xxxxxxxxxx> > > > > Sent: Wednesday, May 22, 2024 9:39 PM > > > > > > > > The driver will then know it should program three different VMIDs for > > > > the same S2 page table, which matches the ARM expectation for > > > > VMID. That is to say we'd pass in the viommu as the pt_id for the > > > > iommu_hwpt_alloc. The viommu would imply both the S2 page table and > > > > any meta information like VMID the driver needs. > > > > > > Can you elaborate the aspect about "three different VMIDs"? > > > > In SMMUv3 the cache is tagged by (VMID,ASID) where ASID is completely > > controlled by the guest. > > > > Every time the guest observes a SMMUv3 instance it is allowed to > > creates its own private ASID number space for that instance. The guest > > could re-use ASID #1 on two instances. > > > > So every SMMUv3 instance plugged into the guest needs to have its own > > unique VMID so that the overlapping ASID's are disambiguate. The above > > would create a VM where: > > > > deva -> vSMMUv3 #1 > > devb -> vSMMUv3 #2 > > devc -> No IOMMU > > This assumes that each vSMMUv3 instance has only one ASID space > i.e. the guest cannot create multiple VMID's itself? Right, the vSMMUv3 in the guest has no support VMID at all. > > I assume the vPPRLog will steal all the PRI before it reaches the > > kernel, so once this is turned on Lu's path won't see anything. > > Okay, then we expect this vqueue object only for HW acceleration > while software-based fault logging is still routed via Baolu's work. Yeah, I think it mirrors the invalidation that way, we have a SW invalidation path and a HW path. The PRI is standards based so it is easier to make a generic API for it. Jason
