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Feature #9598

closed

Need Eager FPU

Added by Robert Mustacchi almost 3 years ago. Updated almost 3 years ago.

Status:
Closed
Priority:
Urgent
Category:
kernel
Start date:
2018-06-13
Due date:
% Done:

100%

Estimated time:
Difficulty:
Hard
Tags:
Gerrit CR:

Description

Historically x86 has used a lazy FPU that restores the FPU registers in the context a #NM handler based on when the FPU is first used after a context switch. It turns out that through speculative execution it is possible to read values out of the FPU before the #NM takes effect. An eager FPU restore defeats this side channel. See CVE-2018-3665.

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