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. Regards, Halil
