On Mon, 2026-01-26 at 23:00 +0100, Halil Pasic wrote: > On Mon, 26 Jan 2026 19:40:09 +0300 > Vladimir Sementsov-Ogievskiy <[email protected]> wrote: > > > > > +/** > > > > + * virtio_queue_set_guest_notifier - set/unset queue or config guest > > > > + * notifier > > > > + * > > > > + * @vdev: the VirtIO device > > > > + * @n: queue number, or VIRTIO_CONFIG_IRQ_IDX to set config notifer > > > > > > Semantically are mixing queue numbers and interrupt indexes here. > > > > That's preexisting logic in virtio_pci_set_guest_notifier_fd_handler(). > > > > But, you are right, that's doesn't answer the question, is it good to share > > the logic with mmio and ccw. > > > > Is config notifier only pci specific, or similar feature may appear in > > future > > for mmio and/or ccw? > > AFAIR there is no notifier for ccw. A possible explanation for > that is, that AFAIK that config space notifications (device -> driver) > are always classic I/O interrupts while queue indicators can be so called > adapter I/O interrupts and irqfd is only available for adapter I/O > interrupts. > > If you like you can have a look at > "4.3.2.6 Setting Up Indicators" in > https://docs.oasis-open.org/virtio/virtio/v1.3/csd01/virtio-v1.3-csd01.html#x1-1940003 > > I see no reason why virtio_config_guest_notifier_read() based, i.e > !irqfd virtio config notifier should not exist or would not work. And I > guess it is needed for certain vhost things. But nevertheless, I can't > find the place where a virtio-ccw config notifier is set up. > > Eric, what is your opinion on this? My current thinking is that > virtio-ccw not having a config notifier is basically a bug.
(Sorry that I missed this; thanks for the ping, Halil) Yeah, we don't have have such a config notifier and I don't recall the history behind it. But I don't know that it's a bug; spec points out config notifications for ccw come as unsolicited interrupts versus config notifier, so not having one is fine by me as far as this refactoring goes. I'll add it to a list of things to play around with, though. Thanks, Eric
