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Re: [PATCH v3 0/7] Enhance PAT init to fix Xorg crashes

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* Toshi Kani <toshi.kani@hpe.com> wrote:

> A Xorg failure on qemu32 was reported as a regression [1] caused by
> 'commit 9cd25aac1f44 ("x86/mm/pat: Emulate PAT when it is disabled")'.
> This patch-set fixes the regression.
> 
> Negative effects of this regression were two failures [2] in Xorg on
> QEMU with QEMU CPU model "qemu32" (-cpu qemu32), which were triggered
> by the fact that its virtual CPU does not support MTRR.
>  #1. copy_process() failed in the check in reserve_pfn_range()
>  #2. error path in copy_process() then hit WARN_ON_ONCE in
>      untrack_pfn().
> 
> These negative effects are caused by two separate bugs, but they can be
> addressed in separate patches.  This patch-set addresses the root cause,
> a long-standing PAT initialization issue.
> 
> Please see the changelog in patch 4/7 for the details of the issue.
> 
> - Patch 1-2 make necessary enhancement to PAT for the fix without
>   breaking Xen.
> - Patch 3 is cleanup.
> - Patch 4 fixes the regression.
> - Patch 5 fixes an MTRR issue related with PAT init.
> - Patch 6 removes PAT init code from Xen.
> - Patch 7 adds PAT init to documentation.
> 
> [1]: https://lkml.org/lkml/2016/3/3/828
> [2]: https://lkml.org/lkml/2016/3/4/775

The changelogs are much improved, I've applied these patches to tip:x86/mm,
thanks Toshi!

> I'd appreciate if someone can test this patch-set on Xen to verify that
> there is no change in "x86/PAT: Configuration [0-7] .." message in dmesg.

So I don't have a Xen setup, but hopefully such testing will happen once these 
changes show up in linux-next, tomorrow or so.

Thanks,

	Ingo

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[PATCH v3 0/7] Enhance PAT init to fix Xorg crashes Toshi Kani <toshi.kani@hpe.com> - 2016-03-23 21:50 +0100
  [PATCH v3 1/7] x86/mm/pat: Add support of non-default PAT MSR setting Toshi Kani <toshi.kani@hpe.com> - 2016-03-23 21:50 +0100
    [tip:x86/mm] x86/mm/pat: Add support of non-default PAT MSR setting tip-bot for Toshi Kani <tipbot@zytor.com> - 2016-03-29 12:40 +0200
  [PATCH v3 5/7] x86/mtrr: Fix PAT init handling when MTRR is disabled Toshi Kani <toshi.kani@hpe.com> - 2016-03-23 22:00 +0100
    [tip:x86/mm] x86/mtrr: Fix PAT init handling when MTRR is disabled tip-bot for Toshi Kani <tipbot@zytor.com> - 2016-03-29 12:50 +0200
  [PATCH v3 6/7] x86/xen,pat: Remove PAT table init code from Xen Toshi Kani <toshi.kani@hpe.com> - 2016-03-23 22:00 +0100
    [tip:x86/mm] x86/xen, pat: Remove PAT table init code from Xen tip-bot for Toshi Kani <tipbot@zytor.com> - 2016-03-29 12:50 +0200
  [PATCH v3 3/7] x86/mm/pat: Replace cpu_has_pat with boot_cpu_has Toshi Kani <toshi.kani@hpe.com> - 2016-03-23 22:00 +0100
    [tip:x86/mm] x86/mm/pat: Replace cpu_has_pat with boot_cpu_has() tip-bot for Toshi Kani <tipbot@zytor.com> - 2016-03-29 12:50 +0200
  [PATCH v3 2/7] x86/mm/pat: Add pat_disable() interface Toshi Kani <toshi.kani@hpe.com> - 2016-03-23 22:00 +0100
    [tip:x86/mm] x86/mm/pat: Add pat_disable() interface tip-bot for Toshi Kani <tipbot@zytor.com> - 2016-03-29 12:50 +0200
  [PATCH v3 7/7] x86/pat: Document PAT initialization Toshi Kani <toshi.kani@hpe.com> - 2016-03-23 22:00 +0100
    [tip:x86/mm] x86/pat: Document the PAT initialization sequence tip-bot for Toshi Kani <tipbot@zytor.com> - 2016-03-29 12:50 +0200
  [PATCH v3 4/6] x86/mtrr: Fix Xorg crashes in Qemu sessions Toshi Kani <toshi.kani@hpe.com> - 2016-03-23 22:00 +0100
    [tip:x86/mm] x86/mtrr: Fix Xorg crashes in Qemu sessions tip-bot for Toshi Kani <tipbot@zytor.com> - 2016-03-29 12:50 +0200
  Re: [PATCH v3 0/7] Enhance PAT init to fix Xorg crashes Ingo Molnar <mingo@kernel.org> - 2016-03-29 12:40 +0200
    Re: [PATCH v3 0/7] Enhance PAT init to fix Xorg crashes Toshi Kani <toshi.kani@hpe.com> - 2016-03-29 15:30 +0200
      Re: [Xen-devel] [PATCH v3 0/7] Enhance PAT init to fix Xorg crashes Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-03-29 16:50 +0200
        Re: [Xen-devel] [PATCH v3 0/7] Enhance PAT init to fix Xorg crashes Toshi Kani <toshi.kani@hpe.com> - 2016-03-29 17:00 +0200
          Re: [Xen-devel] [PATCH v3 0/7] Enhance PAT init to fix Xorg crashes "Luis R. Rodriguez" <mcgrof@suse.com> - 2016-03-30 20:10 +0200
            Re: [LKP] [Xen-devel] [PATCH v3 0/7] Enhance PAT init to fix Xorg crashes "Luis R. Rodriguez" <mcgrof@suse.com> - 2016-03-30 22:20 +0200
              Re: [LKP] [Xen-devel] [PATCH v3 0/7] Enhance PAT init to fix Xorg crashes "Luis R. Rodriguez" <mcgrof@suse.com> - 2016-03-30 22:50 +0200

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