Multqueue Discovery: Allow to set down interfaces

The MQ discovery test is designed to have a 1:1 match between sriov
interfaces in trex VM and dpdk interfaces in testpmd-dpdk-dut VM. This
is a typical workflow deployed by Pre Tempest stage and used in
Multiqueue Discovery stage:

+-------------------------+----------------------------------+
| Name                    | Networks                         |
+-------------------------+----------------------------------+
| testpmd-dpdk-dut        | dpdk_net_nic0_167=10.10.167.143; |
|                         | dpdk_net_nic1_168=10.10.168.160  |
| trex                    | sriov_net_167=10.10.167.149;     |
|                         | sriov_net_168=10.10.168.164      |
+-------------------------+----------------------------------+

The trex VM will inject traffic in sriov_net_167 and sriov_net_168 and
it will be received in dpdk_net_nic0_167 and dpdk_net_nic1_168
respectively on testpmd-dpdk-dut.

In MQ exclusively dedicated scenarios we have a NIC configuration like
this:

- type: ovs_user_bridge
  name: br-dpdk0
  mtu: 9000
  use_dhcp: false
  members:
    - type: ovs_dpdk_port
      name: dpdk2
      mtu: 9000
      rx_queue: 3
      members:
        - type: interface
          name: nic5

- type: ovs_user_bridge
  name: br-dpdk1
  mtu: 9000
  use_dhcp: false
  members:
    - type: ovs_dpdk_port
      name: dpdk3
      mtu: 9000
      rx_queue: 3
      members:
        - type: interface
          name: nic6

Along with this config in tempest_config.yml:

pmd_rxq_affinity:
  - interface: "dpdk2"
    pmd_rxq_affinity: "0:3,1:5,2:7"
  - interface: "dpdk3"
    pmd_rxq_affinity: "0:3,1:5,2:7"

Using the configuration above we got the 1:1 matching between sriov
and dpdk interfaces.

However, for non MQ exclusively dedicated scenarios we have a NIC
configuration like this:

- type: ovs_user_bridge
  name: br-dpdk0
  mtu: 9000
  use_dhcp: false
  members:
  - type: ovs_dpdk_bond
    name: dpdkbond1
    mtu: 9000
    rx_queue: 3
    members:
      - type: ovs_dpdk_port
        name: dpdk2
        members:
          - type: interface
            name: nic5
      - type: ovs_dpdk_port
        name: dpdk3
        members:
          - type: interface
            name: nic6

- type: ovs_user_bridge
  name: br-dpdk1
  mtu: 9000
  use_dhcp: false
  members:
    - type: ovs_dpdk_port
      name: dpdk4
      mtu: 9000
      rx_queue: 3
      members:
	- type: interface
          name: nic4

Then the test failed because the injected traffic in sriov_net_167 and
sriov_net_168 is received in dpdk2, dpdk3, dpdk4 (no 1:1):

sriov_net_167 -> dpdk2, dpdk3
sriov_net_168 -> dpdk4

Since non expected traffic deteced in one of the dpdk interfaces and
error error like this was raised:

Traceback (most recent call last):
  File "/opt/trex/current/multiqueue.py", line 486, in <module>
    main()
  File "/opt/trex/current/multiqueue.py", line 461, in main
    ast.literal_eval(args.pps)),
  File "/opt/trex/current/multiqueue.py", line 190, in parse_pmd_stats
    queue = queues_json[port_index]["queues"][str(queue_id)]
KeyError: '3'

To solve this issue the following config in tempest_config.yml is
necessary:

pmd_rxq_affinity:
  - interface: "dpdk2"
    pmd_rxq_affinity: "0:3,1:5,2:7"
  - interface: "dpdk4"
    pmd_rxq_affinity: "0:3,1:5,2:7"

Along with this new ansible variable:

testpmd_down_interfaces:
  - bridge: "br-dpdk0"
    interface: "dpdk3"

This change provides support for testpmd_down_interfaces. This way,
bringing down one of the dpdk interfaces the 1:1 relatioship between
sriov and dpdk interfaces is kept and the MQ Discovery test can be
executed successfully

Change-Id: I46382eb519d11851529f062d7268944e9b32302f
(cherry picked from commit e69ba19)

Author: rdiazcam

playbooks/tripleo/multiqueue/README.md

@@ -125,6 +125,12 @@ pmd_rxq_affinity: [ {'interface': 'dpdk2', 'pmd_rxq_affinity': '0:3,1:5,2:7'},
                     {'interface': 'dpdk3', 'pmd_rxq_affinity': '0:3,1:5,2:7'} ]
 ```
 
+set down interfaces in OVS bridge
+
+```
+testpmd_down_interfaces: [{'bridge': '<BRIDGE>', 'interface': '<IFACE>'}]
+```
+
 multiqueue config
 
 ```

playbooks/tripleo/multiqueue/multiqueue_learning.yml

@@ -20,6 +20,11 @@
         value: "{{ item.pmd_rxq_affinity }}"
       loop: "{{ pmd_rxq_affinity }}"
 
+    - name: set down interfaces
+      command:
+        cmd: "ovs-ofctl mod-port {{ item.bridge }} {{ item.interface }} down"
+      loop: "{{ testpmd_down_interfaces | default([]) }}"
+
 - hosts: testpmd-dpdk-dut
   gather_facts: no
   pre_tasks:
@@ -143,6 +148,11 @@
         cmd: "ovs-vsctl remove interface {{ item.interface }} other_config pmd-rxq-affinity"
       loop: "{{ pmd_rxq_affinity }}"
 
+    - name: set up interfaces
+      command:
+        cmd: "ovs-ofctl mod-port {{ item.bridge }} {{ item.interface }} up"
+      loop: "{{ testpmd_down_interfaces | default([]) }}"
+
 - hosts: trex
   become: true
   pre_tasks: