Add Virtual GPU Config to nova.conf template

Currently, the list of supported vGPUs is populated automatically
within the Nova playbook when the /sys/class/mdev_bus folder is
present. This will populate the `enabled_vgpu_types` variable with
the full list of vGPUs that are supported by default, with only
the first one listed being used.

This change provides the ability to define a new variable
`nova_enabled_vgpu_types` that will populate the enabled_vgpu_types
config option. It also adds the ability to map vgpu types to PCI
addresses in line with Ussuri updates to provide multi-vGPU support.

Change-Id: Icc0c2cd896d4c9a01601d4d733f38443ad8400d4

defaults/main.yml

@@ -506,6 +506,20 @@ nova_vendor_data_overrides: {}
 nova_api_metadata_uwsgi_ini_overrides: {}
 nova_api_os_compute_uwsgi_ini_overrides: {}
 
+# Enabled vGPU Types - dict defining 'type' and 'address' (optional) of vGPU
+# an address is only required when supporting more than one physical GPU on the host
+# Example 1:
+# nova_enabled_vgpu_types:
+#   - type: nvidia-35
+#
+# Example 2:
+# nova_enabled_vgpu_types:
+#   - type: nvidia-35
+#     address: <device address>
+#   - type: nvidia-36
+#     address: <another device address>
+nova_enabled_vgpu_types: {}
+
 # PCI devices passthrough to nova
 # For SR-IOV please use:
 #   nova_pci_passthrough_whitelist: '{ "physical_network": "<ml2 network name>", "devname": "<physical nic>" }'

tasks/nova_vgpu_detect.yml

@@ -24,7 +24,7 @@
 
 - name: Register a fact for nova enabled_vgpu_types
   set_fact:
-    enabled_vgpu_types: "{{ mdev.stdout_lines | unique }}"
+    discovered_vgpu_types: "{{ mdev.stdout_lines | unique }}"
   when:
     - mdev.stdout_lines is defined
     - mdev.stdout_lines | length > 0

templates/nova.conf.j2

@@ -293,9 +293,14 @@ tracks_instance_changes = {{ nova_scheduler_tracks_instance_changes }}
 [upgrade_levels]
 compute=auto
 
-{% if enabled_vgpu_types is defined %}
+{% if nova_enabled_vgpu_types | length > 0 or discovered_vgpu_types is defined %}
 [devices]
-enabled_vgpu_types = {{ enabled_vgpu_types | join(',') }}
+enabled_vgpu_types = {{ nova_enabled_vgpu_types | map(attribute='type') | list | default(discovered_vgpu_types, true) | unique | join(',') }}
+
+{% for record in nova_enabled_vgpu_types | selectattr('address', 'defined') | list %}
+[vgpu_{{ record.type }}]
+device_addresses = {{ record.address }}
+{% endfor %}
 {% endif %}
 
 {% if nova_pci_passthrough_whitelist or nova_pci_alias %}