On Tue, Aug 14, 2012 at 05:04:16PM +0300, Avi Kivity wrote:
> On 08/14/2012 05:00 PM, Jan Kiszka wrote:
>
> >>> The host can prevent this by leaving disabling the guest pmu. But
> >>> disabling jump labels for real-time kernels may be acceptable too. We
> >>> can probably to it at run time by forcing the slow path at all times.
> >> Yes, it is possible to add module option that will force slow path if
> >> needed.
> >
> > Should I write a patch or will you? Having host-side stop_machine due to
> > such common guest operations is indeed a no-go for RT.
> >
>
> Note that an additional patch is needed for perf, otherwise the guest
> (or a user, but that's less of a concern for realtime) can easily invoke
> stop_machine by configuring and unconfiguring its pmu.
>
>
Are we talking about malicious guests? Why not compile kernel with jump
label disabled if this is serious concern?
--
Gleb.
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