Comment 2 for bug 1930734

Reviewed: https://review.opendev.org/c/openstack/nova/+/794639
Committed: https://opendev.org/openstack/nova/commit/4d8bf15fec15dc3416023e577e0f2c277c216506
Submitter: "Zuul (22348)"
Branch: master

commit 4d8bf15fec15dc3416023e577e0f2c277c216506
Author: Lee Yarwood <email address hidden>
Date: Thu Jun 3 16:37:45 2021 +0100

    libvirt: Set driver_iommu when attaching virtio devices to SEV instance

    As called out in the original spec [1] virtio devices attached to a SEV
    enabled instance must have the iommu attribute enabled. This was done
    within the original implementation of the spec for all virtio devices
    defined when initially spawning the instance but does not include volume
    and interfaces that are later hot plugged.

    This change corrects this for both volumes and nics and in doing so
    slightly refactors the original designer code to make it usable in both
    cases.

    [1] https://specs.openstack.org/openstack/nova-specs/specs/train/implemented/amd-sev-libvirt-support.html#proposed-change

    Closes-Bug: #1930734
    Change-Id: I11131a3f90b8af85e7151b519fb26d225629c391