On Wed, Aug 04, 2021 at 10:59:21PM +0000, Tian, Kevin wrote: > > From: Jason Gunthorpe <jgg@xxxxxxxxxx> > > Sent: Wednesday, August 4, 2021 10:05 PM > > > > On Mon, Aug 02, 2021 at 02:49:44AM +0000, Tian, Kevin wrote: > > > > > Can you elaborate? IMO the user only cares about the label (device cookie > > > plus optional vPASID) which is generated by itself when doing the attaching > > > call, and expects this virtual label being used in various spots (invalidation, > > > page fault, etc.). How the system labels the traffic (the physical RID or RID+ > > > PASID) should be completely invisible to userspace. > > > > I don't think that is true if the vIOMMU driver is also emulating > > PASID. Presumably the same is true for other PASID-like schemes. > > > > I'm getting even more confused with this comment. Isn't it the > consensus from day one that physical PASID should not be exposed > to userspace as doing so breaks live migration? Uh, no? > with PASID emulation vIOMMU only cares about vPASID instead of > pPASID, and the uAPI only requires user to register vPASID instead > of reporting pPASID back to userspace... vPASID is only a feature of one device in existance, so we can't make vPASID mandatory. Jason
