On Wed, 2010-11-03 at 10:43 +0200, Michael S. Tsirkin wrote: > On Wed, Nov 03, 2010 at 09:11:16AM +0100, Jan Kiszka wrote: > > From: Jan Kiszka <jan.kiszka@xxxxxxxxxxx> > > > > PCI 2.3 allows to generically disable IRQ sources at device level. This > > enables us to share IRQs of such devices between on the host side when > > passing them to a guest. This feature is optional, user space has to > > request it explicitly. > > > > Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx> > > > I just realized something. > With this patch, if guest ever looks at > interrupt disable bit, it will go crazy as that bit goes on/off by > itself. I guess we could have an ioctl to set/clear the bit on > device, and have qemu call that on config write into command/status > register. > > There's also something I don't completely unerstand with current code: > how does interrupt sharing work? E.g. can assigned and emulated > devices share an interrupt? I've been pondering this with VFIO too. There it seems to work, even when I enable irqfd. The VFIO kernel/qemu driver needs to filter EOIs based on whether the interrupt was actually asserted by the device, but I think we're likely relying somewhat on interrupts being reasserted to help us keep everything serviced. Alex -- 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
