On 9/7/18 5:39 PM, Jan H. Schönherr wrote: > The collective context switch from one coscheduled set of tasks to another > -- while fast -- is not atomic. If a use-case needs the absolute guarantee > that all tasks of the previous set have stopped executing before any task > of the next set starts executing, an additional hand-shake/barrier needs to > be added.
In case nobody else brought it up yet, you're going to need a handshake to strengthen protection against L1TF attacks. Otherwise, there's still a small window where an attack can occur during the reschedule. Perhaps one could then cause this to happen artificially by repeatedly have a VM do some kind of pause/mwait type operation that might do a reschedule. Jon. -- Computer Architect | Sent with my Fedora powered laptop
