> From: Jason Gunthorpe <jgg@xxxxxxxxxx> > Sent: Saturday, April 16, 2022 9:34 AM > > On Sat, Apr 16, 2022 at 12:42:50AM +0000, Tian, Kevin wrote: > > > Then what about PPC? w/o holding a reference to container is there > > any impact on spapr_tce_table which is attached to the group? > > I don't know the relationship between this table and vfio container > > and whether there is a lifetime dependency in between. > > table seems to have its own FD so it should be refcounted > independently and not indirectly rely on the vfio container. It seemed > like there was enough protection there.. > the table in PPC context refers to a window in the global iova address space. From this angle the reference should be torn down when the group is detached from the container which represents the address space. But given the detach operation also prevents the user from accessing the device, having the reference held by KVM for a while until KVM_DEV_VFIO_GROUP_DEL is called is probably not harmful. In any case this is also worth an explanation similar to what you did for cache coherency. Thanks Kevin
