From 8b4c956bf0ec6c1784e41af2a0598cb49c41461f Mon Sep 17 00:00:00 2001
From: Markos Chandras <mchandras@suse.de>
Date: Mon, 18 Dec 2017 09:52:46 +0000
Subject: [PATCH] roles: bifrost-create-vm-nodes: Set CPU model to 'host-model'

The default CPU model is the QEMU GenuineIntel/QEMU Virtual CPU which
doesn't offer the best possible performance. It's best to switch to the
'host-model' option which should make the vCPU more similar to the
host one.

Change-Id: I677064d14f53eaf6757c07016f4c22909f1b240b
---
 playbooks/roles/bifrost-create-vm-nodes/defaults/main.yml  | 1 +
 .../roles/bifrost-create-vm-nodes/templates/testvm.xml.j2  | 3 +++
 .../notes/vm-host-cpu-type-support-a09768f360372506.yaml   | 7 +++++++
 3 files changed, 11 insertions(+)
 create mode 100644 releasenotes/notes/vm-host-cpu-type-support-a09768f360372506.yaml

diff --git a/playbooks/roles/bifrost-create-vm-nodes/defaults/main.yml b/playbooks/roles/bifrost-create-vm-nodes/defaults/main.yml
index cb6cf8c3d..6f558886c 100644
--- a/playbooks/roles/bifrost-create-vm-nodes/defaults/main.yml
+++ b/playbooks/roles/bifrost-create-vm-nodes/defaults/main.yml
@@ -5,6 +5,7 @@ test_vm_memory_size: "3072"
 test_vm_num_nodes: 1
 test_vm_domain_type: "qemu"
 test_vm_arch: "x86_64"
+test_vm_cpu: "host-model"
 test_vm_groups: {}
 test_vm_default_groups: "{{ lookup('env', 'DEFAULT_HOST_GROUPS').split() | default(['baremetal'], true) }}"
 test_vm_disk_gib: "{{ lookup('env', 'VM_DISK') | default(10, true) }}"
diff --git a/playbooks/roles/bifrost-create-vm-nodes/templates/testvm.xml.j2 b/playbooks/roles/bifrost-create-vm-nodes/templates/testvm.xml.j2
index a2de6b167..15a99bfc7 100644
--- a/playbooks/roles/bifrost-create-vm-nodes/templates/testvm.xml.j2
+++ b/playbooks/roles/bifrost-create-vm-nodes/templates/testvm.xml.j2
@@ -13,6 +13,9 @@
     <apic/>
     <pae/>
   </features>
+  <cpu mode='{{ test_vm_cpu }}'>
+    <model fallback='allow'/>
+  </cpu>
   <clock offset='utc'/>
   <on_poweroff>destroy</on_poweroff>
   <on_reboot>restart</on_reboot>
diff --git a/releasenotes/notes/vm-host-cpu-type-support-a09768f360372506.yaml b/releasenotes/notes/vm-host-cpu-type-support-a09768f360372506.yaml
new file mode 100644
index 000000000..0f63a2f73
--- /dev/null
+++ b/releasenotes/notes/vm-host-cpu-type-support-a09768f360372506.yaml
@@ -0,0 +1,7 @@
+---
+features:
+  - Add support for tweaking the vCPU model for the VMs created
+    by bifrost-create-vm-nodes. The default vCPU model is 'host-model'
+    which should provide the best possible performance whilst using only
+    the CPU features which are understood by libvirt. The model can be
+    changed using the `test_vm_cpu` Ansible variable.