Messages in this thread | | | From | Joel Fernandes <> | Date | Mon, 11 May 2020 10:54:54 -0400 | Subject | Re: [PATCH RFC] Add support for core-wide protection of IRQ and softirq |
| |
On Mon, May 11, 2020 at 9:49 AM Peter Zijlstra <peterz@infradead.org> wrote: > > On Sun, May 10, 2020 at 07:46:52PM -0400, Joel Fernandes (Google) wrote: > > With current core scheduling patchset, non-threaded IRQ and softirq > > victims can leak data from its hyperthread to a sibling hyperthread > > running an attacker. > > > > For MDS, it is possible for the IRQ and softirq handlers to leak data to > > either host or guest attackers. For L1TF, it is possible to leak to > > guest attackers. There is no possible mitigation involving flushing of > > buffers to avoid this since the execution of attacker and victims happen > > concurrently on 2 or more HTs. > > > > The solution in this patch is to monitor the outer-most core-wide > > irq_enter() and irq_exit() executed by any sibling. In between these > > two, we mark the core to be in a special core-wide IRQ state. > > Another possible option is force_irqthreads :-) That would cure it > nicely.
Yes true, it was definitely my "plan B" at one point if this patch showed any regression. Lastly, people not doing force_irqthreads would still leave a hole open and it'd be nice to solve it by "default" than depending on user/sysadmin configuration (same argument against interrupt affinities, it is another knob for the sysadmin/designer to configure correctly, Another argument being not all interrupts can be threaded / affinitized).
Thanks in advance for reviewing the patch,
- Joel
| |