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

From Dave Hansen <dave.hansen@linux.intel.com>
Newsgroups linux.kernel
Subject Re: [PATCH v2] Linux VM workaround for Knights Landing A/D leak
Date 2016-06-15 22:20 +0200
Message-ID <rKps6-77R-35@gated-at.bofh.it> (permalink)
References <rJZHl-7nr-53@gated-at.bofh.it> <rK00F-7Kr-21@gated-at.bofh.it> <rK1pL-88-5@gated-at.bofh.it> <rKiTE-31v-21@gated-at.bofh.it> <rKpir-74l-49@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On 06/15/2016 01:04 PM, Nadav Amit wrote:
> Be careful here. According to the SDM when invalidating a huge-page,
> each 4KB page needs to be invalidated separately. In practice, when
> Linux invalidates 2MB/1GB pages it performs a full TLB flush. The
> full flush may not be required on knights landing, and specifically
> for the workaround, but you should check.  

Where do you get that?  The SDM says: "they (TLB invalidation operations
invalidate all TLB entries corresponding to the translation specified by
the paging structures."

Here's the full paragraph from the SDM

... some processors may choose to cache multiple smaller-page TLB
entries for a translation specified by the paging structures to use a
page larger than 4 KBytes. There is no way for software to be aware
that multiple translations for smaller pages have been used for a large
page. The INVLPG instruction and page faults provide the same assurances
that they provide when a single TLB entry is used: they invalidate all
TLB entries corresponding to the translation specified by the paging
structures.

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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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