Advice on spectre/meltdown and how to mitigate performance impacts

This bug is the result of discussions by the Security SIG. High level overview is here https://ttx.re/openstack-spectre-meltdown-faq.html

A few questions to answer:
1) What is the scope of this documentation activity? Does it include all Spectre and Meltdown vulnerabilities? As far as I can tell out of the eight spectre-ng (https://thehackernews.com/2018/05/intel-spectre-vulnerability.html) vulns, only two are publicly documented:
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-3640
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-3639

2) What is the status of mitigations in OpenStack? CPU manufacturers have not yet completed all remediation, so I believe it is not possible for performance mitigations in OpenStack to be complete. These patches are related (https://review.openstack.org/#/q/I72085016c8756ff88a4da722368f62359bcd7080) but are there others which have already been completed?

3) Can we offer any advice to operators on how to prepare for potential future discoveries in this space?