Re: [PATCH v3 1/3] Introduce a workqueue to deliver PIT timer interrupts.

[Avi Kivity <avi@redhat.com>]

On 04/17/2012 07:15 PM, Jan Kiszka wrote:
> On 2012-04-17 14:06, Avi Kivity wrote:
> > On 04/17/2012 03:03 PM, Gleb Natapov wrote:
> >>>
> >>> KVM_MAX_VCPUS.
> >>>
> >> Ah, so you are worried about malicious guest configuring pit to
> >> broadcast to all its vcpus.
> > 
> > Yes - it can introduce huge amounts of latency this way which is exactly
> > what Jan is trying to prevent.
> > 
> > Though I'm not sure spin_lock_irq() in the realtime tree actually
> > disables irqs (but it's certainly not a good idea in mainline; it's
> > nasty even with just the spinlock).
>
> This depends on how you declare the spin lock type - raw or normal. The
> former will disable irqs, the latter not even preemption (but become a
> mutex).

Yes (and I see no reason to use raw spinlocks here).  Still, for
mainline, are we okay with 254*IPIs?  Maybe it's not so bad and I'm
overinflating the problem.

-- 
error compiling committee.c: too many arguments to function