Meltdown/Spectre mitigation for 4.15 and beyond [LWN.net]

Meltdown/Spectre mitigation for 4.15 and beyond

Posted Jan 17, 2018 1:55 UTC (Wed) by corbet (editor, #1)
In reply to: Meltdown/Spectre mitigation for 4.15 and beyond by roc
Parent article: Meltdown/Spectre mitigation for 4.15 and beyond

That's not too surprising, since retpolines are a defense against variant 2...Am I missing something here?

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Meltdown/Spectre mitigation for 4.15 and beyond

Posted Jan 17, 2018 8:59 UTC (Wed) by roc (subscriber, #30627) [Link] (1 responses)

For mitigations of variant 2, the post links to another post: https://cloudblogs.microsoft.com/microsoftsecure/2018/01/... which is all about system updates, from which we can conclude that user-space code changes for variant 2 are not forthcoming for MSVC users. At least for now.

Meltdown/Spectre mitigation for 4.15 and beyond

Posted Jan 17, 2018 11:13 UTC (Wed) by cesarb (subscriber, #6266) [Link]

That might mean Microsoft believes that the microcode and kernel changes are enough to protect against variant 2 (they probably consider systems where the microcode won't be upgraded a lost cause).

If Microsoft isn't going use retpolines in user space, won't that lead to a performance disadvantage for Linux distributions which decide to recompile everything with retpolines? And what about that variant 1 mitigation they mentioned, will gcc and llvm implement something like it?