Compute-TSX
===========

An Ansible role to verify that the compute nodes have the appropriate TSX flags before
proceeding with an upgrade.

RHEL-8.3 kernel disabled the Intel TSX (Transactional Synchronization Extensions)
feature by default as a preemptive security measure, but it breaks live migration from
RHEL-7.9 (or even RHEL-8.1 or RHEL-8.2) to RHEL-8.3.

Operators are expected to explicitly define the TSX flag in their KernelArgs for the
compute role to prevent live-migration issues during the upgrade process.

This role is intended to be called by tripleo via the kernel deployment templates.

It's also possible to call the role as a standalone.

This also impacts upstream CentOS systems

Requirements
------------

This role needs to be run on an Undercloud with a deployed Overcloud.

Role Variables
--------------

- `compute_tsx_debug`: <'false'> -- Whether or not to print the computed variables during execution
- `compute_tsx_warning`: <'false'> -- Will not return a failure, but will simply print the failure
- `compute_tsx_kernel_args`: <''> -- This is meant to be used when called by tripleo-heat-templates.
- `compute_tsx_8_3_version`: <'4.18.0-240'> -- This is the kernel version that requires to have TSX flag enabled

Dependencies
------------

No dependencies.

Example Playbook
----------------

Standard playbook

    - hosts: nova_libvirt
      roles:
      - { role: compute_tsx}


Reporting playbook with no failure

    - hosts: nova_libvirt
      vars:
      - compute_tsx_warning: true
      roles:
      - { role: compute_tsx}

License
-------

Apache

Author Information
------------------

Red Hat TripleO DFG:Compute Deployment Squad