devstack: use CentOS 9 for DIB IPA builds

Additionally bumps CPU model to host-model as centos9 builds now
require a subset of CPU processors which include advanced features.
Host-model also allows for the VM to still start when running with
pure qemu, as opposed to KVM passthrough.

https://developers.redhat.com/blog/2021/01/05/building-red-hat-enterprise-linux-9-for-the-x86-64-v2-microarchitecture-level#architectural_considerations_for_rhel_9

Change-Id: Ic261efd4bf6f5929687df5e7b1b51b541554af18

devstack/lib/ironic

@@ -314,7 +314,7 @@ IPA_DOWNLOAD_BRANCH=${IPA_DOWNLOAD_BRANCH:-master}
 IPA_DOWNLOAD_BRANCH=$(echo $IPA_DOWNLOAD_BRANCH | tr / -)
 
 # OS for using with DIB images
-IRONIC_DIB_RAMDISK_OS=${IRONIC_DIB_RAMDISK_OS:-centos8}
+IRONIC_DIB_RAMDISK_OS=${IRONIC_DIB_RAMDISK_OS:-centos9}
 IRONIC_DIB_RAMDISK_RELEASE=${IRONIC_DIB_RAMDISK_RELEASE:-}
 
 # Configure URLs required to download ramdisk if we're not building it, and
@@ -341,11 +341,15 @@ fi
 # to build the dib based ironic-python-agent ramdisk.
 IRONIC_DIB_RAMDISK_OPTIONS=${IRONIC_DIB_RAMDISK_OPTIONS:-}
 if [[ -z "$IRONIC_DIB_RAMDISK_OPTIONS" ]]; then
+    # Adapt for DIB naming change
     if [[ "$IRONIC_DIB_RAMDISK_OS" == "centos8" ]]; then
-        # Adapt for DIB naming change
         IRONIC_DIB_RAMDISK_OS=centos
         IRONIC_DIB_RAMDISK_RELEASE=8-stream
     fi
+    if [[ "$IRONIC_DIB_RAMDISK_OS" == "centos9" ]]; then
+        IRONIC_DIB_RAMDISK_OS=centos
+        IRONIC_DIB_RAMDISK_RELEASE=9-stream
+    fi
     IRONIC_DIB_RAMDISK_OPTIONS="$IRONIC_DIB_RAMDISK_OS"
 fi
 # DHCP timeout for the dhcp-all-interfaces element.

devstack/tools/ironic/templates/vm.xml

@@ -17,7 +17,9 @@
     <bios useserial='yes'/>
   </os>
   {% if engine == 'kvm' %}
-    <cpu mode='host-passthrough'/>
+  <cpu mode='host-passthrough'/>
+  {% else %}
+  <cpu mode='host-model'/>
   {% endif %}
   <features>
     <acpi/>