Add nova configuration item to enable memoryBacking Source type file, with shared access

[Martin Schuppert]

https://review.openstack.org/#/c/567876/ implemented file backed memory for instances in libvirt.

File backed memory is enabled per Nova compute host. When enabled, host
will report 'file_backed_memory_capacity' for available memory.

When enabled, instances will create memory backing files in the
directory specified in libvirt's qemu.conf file 'memory_backing_dir'
config option.

This feature is not compatible with memory overcommit, and requires
'ram_allocation_ratio' to be set to 1.0

This is to implement the needed configuration parameters in tripleo.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/604360

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/604360
Committed: https://git.openstack.org/cgit/openstack/tripleo-heat-templates/commit/?id=654961a48092c766b5b814c6fd42f24cc532f1af
Submitter: Zuul
Branch: master

commit 654961a48092c766b5b814c6fd42f24cc532f1af
Author: Martin Schuppert <email address hidden>
Date: Fri Sep 21 11:23:35 2018 +0200

    Add nova file_backed_memory and memory_backing_dir support for qemu.conf

    The libvirt driver now allows utilizing file backed memory for qemu/KVM
    virtual machines, via a new configuration attribute
    ``[libvirt]/file_backed_memory``, defaulting to 0 (disabled).

    ``[libvirt]/file_backed_memory`` specifies the available capacity in MiB
    for file backed memory, at the directory configured for
    ``memory_backing_dir`` in libvirt's ``qemu.conf``. When enabled, the
    libvirt driver will report the configured value for the total memory
    capacity of the node, and will report used memory as the sum of all
    configured guest memory.

    Running Nova with file_backed_memory requires libvirt version 4.0.0 and
    qemu version 2.6.0

    This introduces parameters QemuMemoryBackingDir and NovaLibvirtFileBackedMemory

    Resolves-Bug: 1793687
    Depends-On: I0d9eb21fcab01266e501b7fc63c5b2bbb244956a

    Change-Id: I47e2f92fb2ed3e66d4bf31814eac9090382ef4e1

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.openstack.org/648298

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/648298
Committed: https://git.openstack.org/cgit/openstack/tripleo-heat-templates/commit/?id=89def2b55a5cf73f05cad8ad9ea9f369a243cbba
Submitter: Zuul
Branch: master

commit 89def2b55a5cf73f05cad8ad9ea9f369a243cbba
Author: Oliver Walsh <email address hidden>
Date: Thu Mar 28 00:48:37 2019 +0000

    Fix Nova/Libvirt memory backed file conditions when they are role params

    The QemuMemoryBackingDir and NovaLibvirtFileBackedMemory params can be a role
    parameters however the heat conditions only checked the normal param.

    Change-Id: Iac6d96b2eb3ab92211150572f5a117f07964aaa1
    Related-bug: 1793687