Re: [PATCH 0/8] use jump labels to streamline common APIC configuration

[Gleb Natapov <gleb@redhat.com>]

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.