Que versões do Windows usam o recurso PCID para acelerar o patch do Meltdown?

Question

Eu tenho Windows 7 Enterprise SP1 de 64 bits com um Intel i7-6820HQ (com o último microcódigo rev 0xC6) e InSpectre # 8 diz que eu tenho ambas as proteções, mas SLOWER.

É porque o Windows 7 não usa o recurso PCID? Quais versões são usadas?

Imagens:

PS C:\> Get-SpeculationControlSettings
Speculation control settings for CVE-2017-5715 [branch target injection]
For more information about the output below, please refer to https://support.microsoft.com/en-in/help/4074629

Hardware support for branch target injection mitigation is present: True
Windows OS support for branch target injection mitigation is present: True
Windows OS support for branch target injection mitigation is enabled: True

Speculation control settings for CVE-2017-5754 [rogue data cache load]

Hardware requires kernel VA shadowing: True
Windows OS support for kernel VA shadow is present: True
Windows OS support for kernel VA shadow is enabled: True
Windows OS support for PCID performance optimization is enabled: False [not required for security]

Speculation control settings for CVE-2018-3639 [speculative store bypass]

Hardware is vulnerable to speculative store bypass: True
Hardware support for speculative store bypass mitigation is present: True
Windows OS support for speculative store bypass mitigation is present: True
Windows OS support for speculative store bypass mitigation is enabled system-wide: False


BTIHardwarePresent                  : True
BTIWindowsSupportPresent            : True
BTIWindowsSupportEnabled            : True
BTIDisabledBySystemPolicy           : False
BTIDisabledByNoHardwareSupport      : False
KVAShadowRequired                   : True
KVAShadowWindowsSupportPresent      : True
KVAShadowWindowsSupportEnabled      : True
KVAShadowPcidEnabled                : False
SSBDWindowsSupportPresent           : True
SSBDHardwareVulnerable              : True
SSBDHardwarePresent                 : True
SSBDWindowsSupportEnabledSystemWide : False

PS: Coreinfo v3.31 confirma que o suporte de hardware está lá:

PCID            *       Supports PCIDs and settable CR4.PCIDE
INVPCID         *       Supports INVPCID instruction