> From: Jason Gunthorpe <jgg@xxxxxxxxxx> > Sent: Thursday, August 5, 2021 7:27 PM > > 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. > sure. my point is just that if vPASID is being emulated there is no need of exposing pPASID to user space. Can you give a concrete example where pPASID must be exposed and how the user wants to use this information? Thanks Kevin
