On 14/10/2016 16:56, Wang, Wei W wrote: > > On Friday, October 14, 2016 10:13 PM, Paolo Bonzini wrote: >> On 14/10/2016 16:00, Wang, Wei W wrote: >>>> Why would you do that instead of just using the local APIC?... >>> >>> The interrupt will be delivered to LAPIC - the hypercall hander >>> injects the interrupt via kvm_set_irq(kvm, GSI,..), which finally >>> uses LAPIC, right? >> >> But why do you need that? You can just deliver it to the >> appropriate local APIC interrupt, there's no need to know the GSI. >> The guest knows how it has configured the GSIs. >> >> You haven't explained the use case. > > Sure. One example here is to send an interrupt from a virtio driver > (e.g. the vhost-pci-net that we are working on) on a guest to a > virtio-net device on another guest. In terms of injecting an > interrupt to the virtio-net device, should we give the sender the > related GSI assigned to the virtio-net device (i.e. the GSI of an RX > queue, to notify the virtio-net driver to receive packets from that > RX queue)? In terms of vhost-pci, a write to an MMIO register on the vhost side (the guest->host doorbell) would trigger an irq on the virtio side (the host->guest doorbell). There is no need to know GSIs, they are entirely hidden in QEMU. Paolo > Can you please explain more about "just delivering it to the > appropriate local APIC"? What would be source of the interrupt that > we are injecting to? Thanks. > > Best, Wei > -- 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
