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SubjectRe: [RFC 00/60] Coscheduling for Linux
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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

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