On Thu, Sep 16, 2010 at 05:43:26PM +0200, Gleb Natapov wrote: > On Thu, Sep 16, 2010 at 05:24:11PM +0200, Michael S. Tsirkin wrote: > > On Thu, Sep 16, 2010 at 04:51:17PM +0200, Gleb Natapov wrote: > > > > > What for? Device emulation should do de-assert. > > > > > > > > Sorry, but at this point I have no idea what you call device emulation. > > > The same thing everyone calls device emulation. In case of virtio-net it > > > is in hw/virtio-net.c. If vhost-net is in use device emulation is split > > > between userspace and kernel, but it is still just device emulation. > > > > > > case in point, virtio net does not know about pci at all, > > so it can not deassert. > > > I don't see what PCI has to do with it. virtio-net device implementation is > split between several files. virtio-net/virtio-ring/virtio-pci. All of > them still implement one emulated device. Whoever implemented virtio-net > initially decided to put irq ack register into PCI config space, so code > that does de-assert is in virtio-pci, > but it is still part of emulated > device. > > > > > qemu has code to de-assert. vhost has code to assert. > > > Good. So qemu will de-assert. So what do you mean by > > > "KVM would need to find all irqfd objects mapped to gsi and notify > > > them on deassert" > > > > > > > I would like to optimize level interrupts and stop driving > > > > scheduler insane if at all possible. > > > > > > > Worthy goal. Do it in irqfd. Irqfd shouldn't call kvm_set_irq() if irq > > > level hasn't changed. > > > > Right. Then it needs to know about deasserts. It does not get this > Dessert should be done by qemu writing 0 into irqfd. writing 0 to eventfd does nothing. The way to deassert irq is currently through ioctl and it seems entirely sensible to me to keep it that way. Also - which irqfd :) We need multiple irqfds to map to a single gsi, with kvm doing OR on them. > Assertion and > de-assertion should be done through irqfd. > > information, so when kvm gets deassert ioctl it should > > locate irqfd object and set level to 0. > > See? > No. > > -- > 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
