On 12/01/2009 08:04 PM, Jan Kiszka wrote: > Chris Lalancette wrote: >> KVM_REQ_PENDING_TIMER is set and cleared in a couple of places, >> but it never seems to be actually checked. Remove it. >> > > I would suggest to study the introducing commit > 06e05645661211b9eaadaf6344c335d2e80f0ba2. My strong feeling is that this > removal is wrong. Ah, thanks. Now I see what you mean. In newer KVM, if you are in __vcpu_run() and are in the while (r > 0) loop, after you've done kvm_inject_pending_timer_irqs(), but before you do the next __vcpu_run() (and hence disabled local IRQs), you could receive an hrtimer callback. In that case I guess you would hit the if (vcpu->requests || need_resched() || signal_pending()) test, don't inject the interrupt, and possibly spend a long time in the guest before an unrelated event causes the exit and hence causes the timer injection. Well, that certainly is a bit subtle :). I think I might submit a patch to at least put a comment in vcpu_enter_guest() about this. Unfortunately, this does sort of put a damper on what's going on later in the series. If the i8254 doesn't belong to the BSP (which it really shouldn't), then I don't know which vcpu to raise the bit on. Maybe I can do it in the kvm_irq_delivery_to_apic() function, or kvm_apic_set_irq(). I'll take a look at that. Thanks again for the review, -- Chris Lalancette -- 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
