Lift restriction of choices for 'cpu_model_extra_flags'

Commit c12e3580 (Handle libvirt/cpu_model_extra_flags option)
added support for handling invididual CPU feature flags, but
restricted the options only to "PCID".

In this change, we lift the restriction of choices, and allow
to specify multiple CPU feature flags for all three CPU modes
for the libvirt driver: 'custom', 'host-model' and 'host-passthrough'.

NOTE: The related changes are done in change:
Id4f2cad2e0b0c34a7a68d0b3a6f69b44816f4cd9

Change-Id: I688436ca4449e1865549acc7481ef1978644c528

manifests/compute/libvirt.pp

@@ -35,8 +35,8 @@
 #
 # [*libvirt_cpu_model_extra_flags*]
 #   (optional) This allows specifying granular CPU feature flags when
-#   specifying CPU models. Only valid, if cpu_mode and cpu_model
+#   specifying CPU models. Only has effect if cpu_mode is not set
-#   attributes are specified and only if cpu_mode="custom".
+#   to 'none'.
 #   Defaults to undef
 #
 # [*libvirt_snapshot_image_format*]
@@ -264,19 +264,27 @@ class nova::compute::libvirt (
     validate_string($libvirt_cpu_model)
     nova_config {
       'libvirt/cpu_model': value => $libvirt_cpu_model;
-      'libvirt/cpu_model_extra_flags': value => $libvirt_cpu_model_extra_flags;
     }
   } else {
     nova_config {
       'libvirt/cpu_model': ensure => absent;
-      'libvirt/cpu_model_extra_flags': ensure => absent;
     }
     if $libvirt_cpu_model {
       warning('$libvirt_cpu_model requires that $libvirt_cpu_mode => "custom" and will be ignored')
     }
+  }
 
+  if $libvirt_cpu_mode_real != 'none' {
+    validate_string($libvirt_cpu_model_extra_flags)
+    nova_config {
+      'libvirt/cpu_model_extra_flags': value => $libvirt_cpu_model_extra_flags;
+    }
+  } else {
+    nova_config {
+      'libvirt/cpu_model_extra_flags': ensure => absent;
+    }
     if $libvirt_cpu_model_extra_flags {
-      warning('$libvirt_cpu_model_extra_flags requires that $libvirt_cpu_mode => "custom" and will be ignored')
+      warning('$libvirt_cpu_model_extra_flags requires that $libvirt_cpu_mode is not set to "none" and will be ignored')
     }
   }
 

releasenotes/notes/extra_cpu_flags-2de6915770ac9514.yaml

@@ -1,10 +1,12 @@
 ---
 features:
   - |
-    This allows for specifying granular CPU feature flags, when
+    The libvirt driver now allows specifying individual CPU feature
-    specifying CPU models. It should be set only if ``cpu_mode``
+    flags for guest, via a new configuration parameter
-    and ``cpu_model`` conf parameter are set and ``cpu_mode``
+    ``[libvirt]/cpu_model_extra_flags`` -- this is valid in combination
-    parameter value is set to "custom".
+    with all the three possible values for ``[libvirt]/cpu_mode``:
+    ``custom``, ``host-model`` and ``host-passthrough``. The
+    ``cpu_model_extra_flags`` allows specifying multiple CPU flags.
     The recent "Meltdown" CVE fixes have resulted in critical
     performance penalty which impacts every Nova guest within
     certain CPU models.

spec/classes/nova_compute_libvirt_spec.rb

@@ -13,6 +13,12 @@ describe 'nova::compute::libvirt' do
 
     describe 'with default parameters' do
 
+      let :params do
+        {
+          :libvirt_cpu_model_extra_flags  => 'pcid,pdpe1gb',
+        }
+      end
+
       it { is_expected.to contain_class('nova::params')}
 
       it {
@@ -46,7 +52,7 @@ describe 'nova::compute::libvirt' do
       it { is_expected.to contain_nova_config('libvirt/virt_type').with_value('kvm')}
       it { is_expected.to contain_nova_config('libvirt/cpu_mode').with_value('host-model')}
       it { is_expected.to contain_nova_config('libvirt/cpu_model').with_ensure('absent')}
-      it { is_expected.to contain_nova_config('libvirt/cpu_model_extra_flags').with_ensure('absent')}
+      it { is_expected.to contain_nova_config('libvirt/cpu_model_extra_flags').with_ensure('pcid,pdpe1gb')}
       it { is_expected.to contain_nova_config('libvirt/snapshot_image_format').with_ensure('absent')}
       it { is_expected.to contain_nova_config('libvirt/disk_cachemodes').with_ensure('absent')}
       it { is_expected.to contain_nova_config('libvirt/inject_password').with_value(false)}
@@ -96,7 +102,7 @@ describe 'nova::compute::libvirt' do
       it { is_expected.to contain_nova_config('libvirt/virt_type').with_value('qemu')}
       it { is_expected.to contain_nova_config('libvirt/cpu_mode').with_value('host-passthrough')}
       it { is_expected.to contain_nova_config('libvirt/cpu_model').with_ensure('absent')}
-      it { is_expected.to contain_nova_config('libvirt/cpu_model_extra_flags').with_ensure('absent')}
+      it { is_expected.to contain_nova_config('libvirt/cpu_model_extra_flags').with_ensure('pcid')}
       it { is_expected.to contain_nova_config('libvirt/snapshot_image_format').with_ensure('absent')}
       it { is_expected.to contain_nova_config('libvirt/disk_cachemodes').with_value('file=directsync,block=none')}
       it { is_expected.to contain_nova_config('libvirt/hw_disk_discard').with_value('unmap')}