Port extension to create hardware offloaded ports
The aim of the RFE is to create a new port extension to allow to create ports with hardware offloaded capabilities. Related-Bug: #2013228 Change-Id: I0ee77fd4a0b1fe28b206db7dc13e105ffff122a6
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Rodolfo Alonso Hernandez
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This work is licensed under a Creative Commons Attribution 3.0 Unported
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License.
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http://creativecommons.org/licenses/by/3.0/legalcode
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=================================================
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Port extension to create hardware offloaded ports
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=================================================
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Launchpad bug: https://bugs.launchpad.net/neutron/+bug/2013228
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The aim of the RFE is to create a new port extension to allow to create ports
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with hardware offloaded capabilities.
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Problem Description
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===================
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The RFE [1]_ introduced the capability of creating a port that could use the
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hardware offload support implemented in Open vSwitch [2]_. This feature was
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implemented in the following set of patches (initially for ML2/OVS): [3]_,
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[4]_ and [5]_.
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In order to create a port with hardware offload capabilities, it is needed to
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define the VNIC type and set a specific value in the port binding profile::
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openstack port create --vnic-type direct \
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--binding-profile '{"capabilities": ["switchdev"]}' port_hwol
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This method to create a port has several drawbacks:
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* The port binding profile field is an admin only parameter by default.
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The values contained in this field can have references to PCI addresses of
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the host and should not be modified by a non-admin user.
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* Actually this parameter should not be written by Neutron, only by Nova when
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the port is bound.
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Proposed Change
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===============
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This RFE proposes to create a new port extension, called
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"port-hardware-offload", that will replace the need of manually defining the
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port binding profile information when creating the port; please note that
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this is referring only to the port creation process. This API extension
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consists of a string parameter that will be "None" by default. This string
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will be the hardware offload type; OpenStack Neutron and Nova are currently
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supporting only "switchdev" [6]_. The strings allowed by the API will be
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limited to a set of defined constants.
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This new string parameter will be passed to Nova along with the port
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information dictionary. Nova will use this parameter instead of the port
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binding profile information to command ``os-vif`` to create the
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corresponding layer 1 port (a devlink port [3]_ [7]_).
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Because of this Nova-Neutron communication, this RFE is going to be implemented
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in two steps:
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* The first one will implement only the Neutron and OSC (plus the OpenstackSDK
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bits) code. The port dictionary passed to Nova will contain both the new
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parameter added in this RFE and the port binding profile, that will be added
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internally by Neutron when the new paramter is not "None".
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* The second step involves the Nova implementation. This change implies that
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Nova can read the port new parameter and create the corresponding port. The
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port binding profile information passed by Neutron will be irrelevant.
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.. NOTE::
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The scope of this RFE, as discussed during the presentation of this new
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feature in the Neutron drivers meeting, involves only the first step. The
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Nova code change will be covered in other RFE and spec.
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Client Impact
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-------------
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The OSC and OpenstackSDK projects will be updated in order to be able to create
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a port using this new extension. Port creation example::
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openstack port create --vnic-type direct \
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--hardware-offload-type switchdev port_hwol
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The new string field will be visible when showing the port resource.
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This spec is not covering the Nova migration from reading the port binding
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profile to using the new parameter provider in the port definition. As
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commented in the first section, Neutron will still populate the port binding
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profile as long as the "hardware-offload-type" is provided in the port
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creation command. In order to stop users to create a port with the old
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method, the OSC will check if the "capabilities" key is provided inside the
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port binding profile and a warning will be printed in the command line,
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encouraging the user to create the port using the "hardware-offload-type"
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parameter.
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REST API Impact
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---------------
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Proposed attribute::
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RESOURCE_ATTRIBUTE_MAP = {
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port.COLLECTION_NAME: {
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"hardware_offload_type": {
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'allow_post': True,
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'allow_put': False,
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'convert_to': converters.convert_to_string,
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'default': None,
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'is_visible': True,
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'is_filter': True,
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'validate': {
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'type:values': constants.VALID_HWOL_TYPES}
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}
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}
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}
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Sample REST calls::
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POST /v2.0/ports
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{
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"port": {
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...
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"hardware_offload_type": "switchdev"
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}
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Response:
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{
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"port": {
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"id": "<id>",
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...
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"hardware_offload_type": "switchdev"
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}
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}
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Data Model Impact
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-----------------
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This RFE proposes to create a child table to ``ports``, called
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``port_hardware_offload``.
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.. table:: **Port hardware offload**
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===================== ======== ==== =====================================
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Attribute Type CRUD Description
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===================== ======== ==== =====================================
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port_id uuid-str CR Unique identifier for the port object
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hardware_offload_type str CR String to indicate the hardware
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offload type
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===================== ======== ==== =====================================
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Security Impact
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---------------
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By default, this new field will be writable by the admin only. However, the
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admin can consider changing the rule owner and allow any project user to create
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a port defining this parameter::
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policy.DocumentedRuleDefault(
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name='create_port:hardware_offload_type',
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check_str=base.ADMIN,
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scope_types=['project'],
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operations=ACTION_POST
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)
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This rule change was completely discouraged for the rule
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'create_port:binding:profile' for the reasons provided in the problem
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description.
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Performance Impact
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------------------
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The port resource view will now require a new "JOIN" operation between the
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``ports`` table and the ``ports_hardware_offload`` table when building the
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port OVO. However there will be a 1:1 relationship between both tables and the
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data retrieved from the child table is minimal (two columns).
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Other Impact
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------------
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None.
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Implementation
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==============
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Assignee(s)
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-----------
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Primary assignees:
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Rodolfo Alonso Hernandez <ralonsoh@redhat.com> (IRC: ralonsoh)
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Work Items
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----------
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* API implementation (neutron-lib and Neutron).
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* Database migration (Neutron)
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* CLI implementation (OpenstackSDK and OSC)
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* Documentation.
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* Tests and CI related changes.
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Testing
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=======
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* Unit/functional tests.
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* Fullstack API tests.
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Documentation Impact
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====================
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User Documentation
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------------------
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Document the new way to create hardware offload ports and deprecate the older
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method.
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References
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==========
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.. [1] [RFE] SR-IOV accelerated OVS integration
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https://bugs.launchpad.net/neutron/+bug/1627987
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.. [2] https://mail.openvswitch.org/pipermail/ovs-dev/2017-April/330606.html
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.. [3] https://review.opendev.org/c/openstack/os-vif/+/460278
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.. [4] https://review.opendev.org/c/openstack/neutron/+/275616
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.. [5] https://review.opendev.org/c/openstack/neutron/+/499203
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.. [6] https://docs.kernel.org/networking/switchdev.html
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.. [7] https://www.kernel.org/doc/html/next/networking/devlink/devlink-port.html
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