Greetings from the VMware Security Response Center!
The reason we have done this is to clarify which of these issues have been mitigated against currently known variants of the different vulnerabilities.
Because CVE-2017-5753 (Meltdown) is considered by some to be the most severe/exploitable of the issues, we did not want to wait for CVE-2017-5715 (Spectre-2) mitigations while Spectre-1/Meltdown fixes were ready to ship. We also understand that some customers may want to delay updating until all mitigations are in place. While we strongly recommend taking updates as soon as they become available, we wanted to be transparent about the fact that more updates are on the way.
Products will be enumerated in a new advisory when either of the following requirements are met to mitigate CVE-2017-5715:
1. IBPB/IBRS is supported.
2. Retpoline is supported.
Because this is an ongoing issue, VMware appliances will continue to accept improved open source mitigations as they are created.