> From: Jason Gunthorpe <jgg@xxxxxxxxxx> > Sent: Tuesday, March 30, 2021 9:28 PM > > On Tue, Mar 30, 2021 at 04:14:58AM +0000, Tian, Kevin wrote: > > > One correction. The mdev should still construct the list of allowed PASID's > as > > you said (by listening to IOASID_BIND/UNBIND event), in addition to the > ioasid > > set maintained per VM (updated when a PASID is allocated/freed). The > per-VM > > set is required for inter-VM isolation (verified when a pgtable is bound to > the > > mdev/PASID), while the mdev's own list is necessary for intra-VM isolation > when > > multiple mdevs are assigned to the same VM (verified before loading a > PASID > > to the mdev). This series just handles the general part i.e. per-VM ioasid > set and > > leaves the mdev's own list to be managed by specific mdev driver which > listens > > to various IOASID events). > > This is better, but I don't understand why we need such a convoluted > design. > > Get rid of the ioasid set. > > Each driver has its own list of allowed ioasids. First, I agree with you it's necessary to have a per-device allowed ioasid list. But besides it, I think we still need to ensure the ioasid used by a VM is really allocated to this VM. A VM should not use an ioasid allocated to another VM. right? Actually, this is the major intention for introducing ioasid_set. > Register a ioasid in the driver's list by passing the fd and ioasid # The fd here is a device fd. Am I right? If yes, your idea is ioasid is allocated via /dev/ioasid and associated with device fd via either VFIO or vDPA ioctl. right? sorry I may be asking silly questions but really need to ensure we are talking in the same page. > No listening to events. A simple understandable security model. For this suggestion, I have a little bit concern if we may have A-B/B-A lock sequence issue since it requires the /dev/ioasid (if it supports) to call back into VFIO/VDPA to check if the ioasid has been registered to device FD and record it in the per-device list. right? Let's have more discussion based on the skeleton sent by Kevin. Regards, Yi Liu
