Feature #9598

Need Eager FPU

Added by Robert Mustacchi 3 months ago. Updated 3 months ago.

Status:ClosedStart date:2018-06-13
Priority:UrgentDue date:
Assignee:Robert Mustacchi% Done:

100%

Category:kernel
Target version:-
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 3 months 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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