Re: [PATCH v3 1/3] Introduce a workqueue to deliver PIT timer interrupts.
|[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]|
On Tue, Apr 17, 2012 at 07:17:11PM +0300, Avi Kivity wrote: > 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 It was raw spinlock until f4f510508741680e423524c222f615276ca6222c. > mainline, are we okay with 254*IPIs? Maybe it's not so bad and I'm > overinflating the problem. > Isn't 254*IPIs can also happen if application changes memory mapping? -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html