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Feature #9598

Need Eager FPU

Added by Robert Mustacchi over 1 year ago. Updated over 1 year ago.

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

100%

Estimated time:
Difficulty:
Hard
Tags:

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.

History

#1

Updated by Electric Monk over 1 year ago

  • Status changed from New to Closed

git commit 4c28a617e3922d92a58e813a5b955eb526b9c386

commit  4c28a617e3922d92a58e813a5b955eb526b9c386
Author: Robert Mustacchi <rm@joyent.com>
Date:   2018-06-19T19:34:37.000Z

    9598 Need Eager FPU
    Reviewed by: Jerry Jelinek <jerry.jelinek@joyent.com>
    Reviewed by: Patrick Mooney <patrick.mooney@joyent.com>
    Reviewed by: Bryan Cantrill <bryan@joyent.com>
    Reviewed by: John Levon <john.levon@joyent.com>
    Reviewed by: Toomas Soome <tsoome@me.com>
    Approved by: Richard Lowe <richlowe@richlowe.net>

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