Fri, Mar 15, 2024 at 05:55:51PM CET, jonah.pal...@oracle.com wrote: >The goal of these patches are to add support to a variety of virtio and >vhost devices for the VIRTIO_F_NOTIFICATION_DATA transport feature. This >feature indicates that a driver will pass extra data (instead of just a >virtqueue's index) when notifying the corresponding device. > >The data passed in by the driver when this feature is enabled varies in >format depending on if the device is using a split or packed virtqueue >layout: > > Split VQ > - Upper 16 bits: shadow_avail_idx > - Lower 16 bits: virtqueue index > > Packed VQ > - Upper 16 bits: 1-bit wrap counter & 15-bit shadow_avail_idx > - Lower 16 bits: virtqueue index > >Also, due to the limitations of ioeventfd not being able to carry the >extra provided by the driver, having both VIRTIO_F_NOTIFICATION_DATA >feature and ioeventfd enabled is a functional mismatch. The user must >explicitly disable ioeventfd for the device in the Qemu arguments when >using this feature, else the device will fail to complete realization. > >For example, a device must explicitly enable notification_data as well >as disable ioeventfd: > > -device virtio-scsi-pci,...,ioeventfd=off,notification_data=on > >A significant aspect of this effort has been to maintain compatibility >across different backends. As such, the feature is offered by backend >devices only when supported, with fallback mechanisms where backend >support is absent. > >v3: Validate VQ idx via. virtio_queue_get_num() (pci, mmio, ccw) > Rename virtio_queue_set_shadow_avail_data > Only pass in upper 16 bits of 32-bit extra data (was redundant) > Make notification compatibility check function static > Drop tags on patches 1/6, 3/6, and 4/6 > >v2: Don't disable ioeventfd by default, user must disable it > Drop tags on patch 2/6 > >Jonah Palmer (6): > virtio/virtio-pci: Handle extra notification data > virtio: Prevent creation of device using notification-data with ioeventfd > virtio-mmio: Handle extra notification data > virtio-ccw: Handle extra notification data > vhost/vhost-user: Add VIRTIO_F_NOTIFICATION_DATA to vhost feature bits > virtio: Add VIRTIO_F_NOTIFICATION_DATA property definition
Jonah, do you have kernel patches to add this feature as well? Thanks!
