Intel Memory Access Design Flaw Already Addressed by Apple in macOS 10.13.2

Discussion in 'MacRumors.com News Discussion' started by MacRumors, Jan 3, 2018.

  1. Mad Mac Maniac macrumors 601

    Mad Mac Maniac

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    #26
    Wow, if Windows sees a 30% slowdown and Macs have a negligible impact that would really be something. I don't know if that would be good design/coding on Apple's part or just plain luck. Definitely good news for my 2013 MBA which I am planning on keeping as long as I can. I'm shooting for 2023!
     
  2. djlythium macrumors 6502a

    djlythium

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    #27
    So, what does the ‘double map’ do anyway?
     
  3. xgman macrumors 601

    xgman

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    #28
    There is a new 10.13.3 beta ver out today for devs.
     
  4. belvdr macrumors 603

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    #29
    This has nothing to do with CPU utilization. Rather, you will see a performance penalty when an applications makes system calls, such as to files or network access. Essentially it occurs when ring 3 needs to access something at the more privileged ring 0.
     
  5. SecuritySteve macrumors 6502

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    #31
    Essentially, the vulnerability resides in Intel Processors ability to 'speculate' as to what code needs to be executed next, and execute it in advance so that it is cached and ready for the real execution. The vulnerability allows for the security context of that code execution to escalate from user land (referred to as ring 3) to kernel land (referred to as ring 0). The significance is that the Kernel memory houses sensitive information on the system that, once read, can be leveraged to escalate privileges. Double mapping adds an additional buffer between the kernel and user, which mitigates but doesn't completely solve the vulnerability. That is why additional 'tweaks' are necessary in 10.13.3.
     
  6. MacsRgr8 macrumors 604

    MacsRgr8

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    #32
    Same here.
     
  7. juanmj93 macrumors newbie

    juanmj93

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    #33
  8. iPhysicist macrumors 65816

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    #34
    This was long overdue!
     
  9. belvdr macrumors 603

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    #35
    Was it confirmed that feature causes this? I didn’t get a chance to keep up with this today and last I read it was speculative whether that feature was the cause.
     
  10. noxivs macrumors newbie

    noxivs

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    #36
    So it is only supposed to affect the file browsing performance on the OS? This may only be an issue with server grade workloads then. Hardly anything to do with in-application workloads?
     
  11. PG(Austin) macrumors regular

    PG(Austin)

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    #37
    My thoughts exactly.
     
  12. jav6454 macrumors P6

    jav6454

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    #38
    The performance hit is when a program continuously access kernel information (such as network, I/O from SSD/HDD or other add on cards).

    However, programs, like games, that live in RAM and don't interact much with the kernel, will not see the performance hit.

    That said, most hard hit programs are those encoding videos, processing pictures and web service servers.
     
  13. belvdr macrumors 603

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    #39
    Or any other device access really. At this point, I would consider any workload potentially impacted until tested. FWIW, I would not expect casual desktop users or many power users to notice any change.
     
  14. SecuritySteve macrumors 6502

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    #40
    Judging from the Linux kernel code commits, and the double buffer solution, it's almost certainly the case.
     
  15. krell100 macrumors member

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  16. juanmj93 macrumors newbie

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  17. longofest, Jan 3, 2018
    Last edited: Jan 3, 2018

    longofest Editor emeritus

    longofest

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    #43
    It would obviously depend on what kind of workload you run. I've seen some people say that IOP heavy workloads could suffer 20-30% (or more)
     
  18. SecuritySteve macrumors 6502

    SecuritySteve

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    #44
    Yes. All processors Skylake and back are affected. (Supposedly).
     
  19. nutmac macrumors 68040

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    #45
    Intel has imposed an embargo on discussing this issue.
     
  20. nt5672 macrumors 68000

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    #46
    Maybe they are and maybe not. They did not say it was completely solved and we don't know the extent of the slowdown with the final solution. And it appears that the final solution is coming after linux (an open source volunteer effort) released their solution. So I don't see any positive here at all, other than the fact that Apple did not deny it as they have in the past with other problems. But with the publicity, they had no choice.
     
  21. SeaFox macrumors 68020

    SeaFox

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    #47
    [​IMG]
     
  22. SecuritySteve macrumors 6502

    SecuritySteve

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    #48
    You're misunderstanding the issue. The solution to the Linux kernel and the solution Apple has released here are different, and Apple released theirs first. The issue is not completely fixed with Apple's solution, but in principal the solution could be complete with a few tweaks. In the mean time, most users are almost completely safe and haven't noticed a slowdown. I'd say score one for Apple.
     
  23. thejadedmonkey macrumors 604

    thejadedmonkey

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    #49
    And VMs, which I use a lot of thanks to Docker and Kubernetes.

    I'm curious too, about the status of 10.12.6, as I'm not able to upgrade my OS until early March, at the earliest...
     
  24. AppleInLVX macrumors 65816

    AppleInLVX

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    #50
    FWIW, I didn't notice a difference either.
     

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