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Re: [PATCH v2] Linux VM workaround for Knights Landing A/D leak

From Borislav Petkov <bp@alien8.de>
Newsgroups linux.kernel
Subject Re: [PATCH v2] Linux VM workaround for Knights Landing A/D leak
Date 2016-06-14 21:20 +0200
Message-ID <rK22u-BW-11@gated-at.bofh.it> (permalink)
References <rJZHl-7nr-53@gated-at.bofh.it> <rK00F-7Kr-21@gated-at.bofh.it> <rK0k2-7St-27@gated-at.bofh.it> <rK1pN-88-59@gated-at.bofh.it> <rK1J7-fP-23@gated-at.bofh.it>
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On Tue, Jun 14, 2016 at 11:54:24AM -0700, Dave Hansen wrote:
> Lukasz, Borislav suggested using static_cpu_has_bug(), which will do the
> alternatives patching.  It's definitely the right thing to use here.

Yeah, either that or do an

alternative_call(null_func, fix_pte_peak, X86_BUG_PTE_LEAK, ...)

or so and you'll need a dummy function to call on !X86_BUG_PTE_LEAK
CPUs.

The static_cpu_has_bug() thing should be most likely a penalty
of a single JMP (I have to look at the asm) but then since the
callers are inlined, you'll have to patch all those places where
*ptep_get_and_clear() get inlined.

Shouldn't be a big deal still but...

"debug-alternative" and a kvm guest should help you there to get a quick
idea.

HTH.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.

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Thread

[PATCH] Linux VM workaround for Knights Landing A/D leak Lukasz Anaczkowski <lukasz.anaczkowski@intel.com> - 2016-06-14 18:00 +0200
  Re: [PATCH] Linux VM workaround for Knights Landing A/D leak kbuild test robot <lkp@intel.com> - 2016-06-14 18:40 +0200
  Re: [PATCH] Linux VM workaround for Knights Landing A/D leak Nadav Amit <nadav.amit@gmail.com> - 2016-06-14 18:50 +0200
    RE: [PATCH] Linux VM workaround for Knights Landing A/D leak "Anaczkowski, Lukasz" <lukasz.anaczkowski@intel.com> - 2016-06-14 19:00 +0200
    [PATCH v2] Linux VM workaround for Knights Landing A/D leak Lukasz Anaczkowski <lukasz.anaczkowski@intel.com> - 2016-06-14 19:10 +0200
      Re: [PATCH v2] Linux VM workaround for Knights Landing A/D leak Dave Hansen <dave.hansen@linux.intel.com> - 2016-06-14 19:30 +0200
        Re: [PATCH v2] Linux VM workaround for Knights Landing A/D leak One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-06-14 20:40 +0200
          Re: [PATCH v2] Linux VM workaround for Knights Landing A/D leak Dave Hansen <dave.hansen@linux.intel.com> - 2016-06-14 21:00 +0200
            Re: [PATCH v2] Linux VM workaround for Knights Landing A/D leak Borislav Petkov <bp@alien8.de> - 2016-06-14 21:20 +0200
              Re: [PATCH v2] Linux VM workaround for Knights Landing A/D leak "H. Peter Anvin" <hpa@zytor.com> - 2016-06-14 22:30 +0200
                Re: [PATCH v2] Linux VM workaround for Knights Landing A/D leak Borislav Petkov <bp@alien8.de> - 2016-06-14 22:50 +0200
                Re: [PATCH v2] Linux VM workaround for Knights Landing A/D leak "H. Peter Anvin" <hpa@zytor.com> - 2016-06-14 23:00 +0200
                Re: [PATCH v2] Linux VM workaround for Knights Landing A/D leak "H. Peter Anvin" <hpa@zytor.com> - 2016-06-14 23:10 +0200
                Re: [PATCH v2] Linux VM workaround for Knights Landing A/D leak Borislav Petkov <bp@alien8.de> - 2016-06-14 23:10 +0200
                Re: [PATCH v2] Linux VM workaround for Knights Landing A/D leak "H. Peter Anvin" <hpa@zytor.com> - 2016-06-14 23:20 +0200
      Re: [PATCH v2] Linux VM workaround for Knights Landing A/D leak Borislav Petkov <bp@alien8.de> - 2016-06-14 20:20 +0200
        RE: [PATCH v2] Linux VM workaround for Knights Landing A/D leak "Anaczkowski, Lukasz" <lukasz.anaczkowski@intel.com> - 2016-06-15 15:20 +0200
      Re: [PATCH v2] Linux VM workaround for Knights Landing A/D leak Nadav Amit <nadav.amit@gmail.com> - 2016-06-14 20:40 +0200
        RE: [PATCH v2] Linux VM workaround for Knights Landing A/D leak "Anaczkowski, Lukasz" <lukasz.anaczkowski@intel.com> - 2016-06-15 15:20 +0200
          Re: [PATCH v2] Linux VM workaround for Knights Landing A/D leak Nadav Amit <nadav.amit@gmail.com> - 2016-06-15 22:10 +0200
            Re: [PATCH v2] Linux VM workaround for Knights Landing A/D leak Dave Hansen <dave.hansen@linux.intel.com> - 2016-06-15 22:20 +0200
              Re: [PATCH v2] Linux VM workaround for Knights Landing A/D leak Nadav Amit <nadav.amit@gmail.com> - 2016-06-15 22:30 +0200
      [PATCH v3] Linux VM workaround for Knights Landing A/D leak Lukasz Anaczkowski <lukasz.anaczkowski@intel.com> - 2016-06-16 17:20 +0200
        Re: [PATCH v3] Linux VM workaround for Knights Landing A/D leak Nadav Amit <nadav.amit@gmail.com> - 2016-06-16 18:50 +0200
        Re: [PATCH v3] Linux VM workaround for Knights Landing A/D leak Dave Hansen <dave.hansen@linux.intel.com> - 2016-06-16 22:30 +0200
    Re: [PATCH] Linux VM workaround for Knights Landing A/D leak Dave Hansen <dave.hansen@linux.intel.com> - 2016-06-14 19:20 +0200
      Re: [PATCH] Linux VM workaround for Knights Landing A/D leak Nadav Amit <nadav.amit@gmail.com> - 2016-06-14 22:20 +0200
        Re: [PATCH] Linux VM workaround for Knights Landing A/D leak Dave Hansen <dave.hansen@linux.intel.com> - 2016-06-14 23:40 +0200
          Re: [PATCH] Linux VM workaround for Knights Landing A/D leak Andy Lutomirski <luto@amacapital.net> - 2016-06-15 04:30 +0200
            Re: [PATCH] Linux VM workaround for Knights Landing A/D leak Nadav Amit <nadav.amit@gmail.com> - 2016-06-15 04:40 +0200
              Re: [PATCH] Linux VM workaround for Knights Landing A/D leak Andy Lutomirski <luto@amacapital.net> - 2016-06-15 04:40 +0200
                Re: [PATCH] Linux VM workaround for Knights Landing A/D leak Nadav Amit <nadav.amit@gmail.com> - 2016-06-15 04:50 +0200
                Re: [PATCH] Linux VM workaround for Knights Landing A/D leak Andy Lutomirski <luto@amacapital.net> - 2016-06-15 05:10 +0200
          Re: [PATCH] Linux VM workaround for Knights Landing A/D leak Nadav Amit <nadav.amit@gmail.com> - 2016-06-15 05:30 +0200
  Re: [PATCH] Linux VM workaround for Knights Landing A/D leak kbuild test robot <lkp@intel.com> - 2016-06-14 19:00 +0200
  Re: [PATCH] Linux VM workaround for Knights Landing A/D leak Dave Hansen <dave.hansen@linux.intel.com> - 2016-06-14 19:30 +0200
    RE: [PATCH] Linux VM workaround for Knights Landing A/D leak "Anaczkowski, Lukasz" <lukasz.anaczkowski@intel.com> - 2016-06-15 15:10 +0200

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