tripleo-kernel: prevent reboot when TSX flag was added

During the 16.2 upgrade path, we enforce the inclusion of tsx flag by
operators. If there was already kernelargs present, the node won't get
rebooted, but if it's a new KernelArgs, the node will get rebooted as
per the related bug.

We want to prevent the unexpected reboot of nodes with workload when
the TSX flag was added.

Related: https://bugzilla.redhat.com/show_bug.cgi?id=1975240
Change-Id: Ib6140c8991469c950fd7e1b323c614103394e3f1
(cherry picked from commit a15e925110)

tripleo_ansible/roles/tripleo_kernel/tasks/kernelargs.yml

@@ -18,6 +18,30 @@
   command: cat /proc/cmdline
   register: cmdline
 
+- name: TSX KernelArgs compute node reboot prevention
+  when:
+    - '"nova_libvirt" in groups'
+  block:
+    - name: Check if node has a nova.conf
+      stat:
+        path: /var/lib/config-data/puppet-generated/nova_libvirt/etc/nova/nova.conf
+      register: nova_conf_check
+
+    - name: Enabling defer_reboot when TSX was added or appended
+      when:
+      - nova_conf_check.stat.exists
+      - tripleo_kernel_args is regex("^[\s]*tsx=[^\s]+[\s]*$")
+      block:
+        - name: Warn operator about workload protection
+          debug:
+            msg: |
+              Automated reboot for this node has been defered because it is already provisionned.
+              Please schedule a manual reboot after this deployment is completed.
+
+        - name: Setting defer reboot fact
+          set_fact:
+            tripleo_kernel_defer_reboot: true
+
 - name: Check if the kernelargs entry is already present in the file
   replace:
     regexp: TRIPLEO_HEAT_TEMPLATE_KERNEL_ARGS