On 04/10/2012 06:14 PM, Michael S. Tsirkin wrote: > On Tue, Apr 10, 2012 at 06:00:51PM +0300, Avi Kivity wrote: > > On 04/10/2012 05:53 PM, Michael S. Tsirkin wrote: > > > > > > > > > > Yes. But we can and it's easier than figuring out priorities. > > > > > I am guessing such collisions are rare, right? > > > > > > > > It's pretty easy, if there is something in IRR but > > > > kvm_lapic_has_interrupt() returns -1, then we need to disable eoi avoidance. > > > > > > I only see kvm_apic_has_interrupt - is this what you mean? > > > > Yes, sorry. > > > > It's not clear whether to do the check in kvm_apic_has_interrupt() or > > kvm_apic_get_interrupt() - the latter is called only after interrupts > > are enabled, so it looks like a better place (EOIs while interrupts are > > disabled have no effect). But need to make sure those functions are > > actually called, since they're protected by KVM_REQ_EVENT. > > Sorry not sure what you mean by "make sure" - read the code carefully? Yes. And I mean, get called at the right time. > > > > Better to keep everything per-cpu. The code is in virt/kvm/ioapic.c > > Hmm. Disabling for level handles the ack notifiers > issue as well, which I forgot about. > It's a tough call. You think looking at > TMR in kvm_get_apic_interrupt is safe? Yes, it's read only from the guest point of view IIRC. > > > > > > > Why do we care about > > > > level-triggered interrupts? Everything uses MSI or edge-triggered > > > > IOAPIC interrupts these days. > > > > > > Well lots of emulated devices don't yet. > > > They probably should but it's nice to be able to > > > test with e.g. e1000 emulation not just virtio. > > > > > > e1000 doesn't support msi? > > qemu emulation doesn't. > Can be changed if someone's really interested. But really, avoiding EOIs for e1000 won't help it much. -- error compiling committee.c: too many arguments to function -- 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
