Enable Agilio vRouter offloads in Nova

[Jan Gutter]

SmartNICs allow complex packet processing on the NIC. In order to support
hardware acceleration for them, Nova core needs modifications to support the combination of VIF and vRouter plugging they support. This proposes a
hybrid SR-IOV and vRouter model to enable acceleration.

[OpenContrail Admin (ci-admin-f)]

Review in progress for https://review.opencontrail.org/43209
Submitter: Jan Gutter (<email address hidden>)

[OpenContrail Admin (ci-admin-f)]

Reviewed: https://review.opencontrail.org/43209
Committed: http://github.com/Juniper/nova/commit/8496d4eae14abc532cf47d4423d336a2b35df46e
Submitter: Zuul (<email address hidden>)
Branch: contrail/ocata-15.0.6

commit 8496d4eae14abc532cf47d4423d336a2b35df46e
Author: Jan Gutter <email address hidden>
Date: Tue May 22 11:00:40 2018 +0200

Add plumbing for hardware offloads

* This change expands the VNIC type support for the vrouter VIF type by
adding 'direct' and 'virtio-forwarder' plugging support.

* After this change, the vrouter VIF type will support the following three
modes:
* 'normal': the 'classic' tap-style VNIC plugged into the instance,
* 'direct': a PCI Virtual Function is passed through to the instance,
* 'virtio-forwarder': a PCI Virtual Function is proxied to the
instance via a vhost-user virtio forwarder.

* The libvirt xml generation code was updated to support the modes.

* The Nova legacy VIF plugging code was updated to support the modes.

* The corresponding review on OpenContrail is currently at:
https://review.opencontrail.org/#/c/42850/ for master
https://review.opencontrail.org/#/c/42478/ for 4.1

Change-Id: I73908368d48b0c6f8780b8dabe30b83875efa0b8
Closes-Bug: #1772612
Signed-off-by: Jan Gutter <email address hidden>