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Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table

From Toshi Kani <toshi.kani@hpe.com>
Newsgroups linux.kernel
Subject Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table
Date 2016-03-15 17:20 +0100
Message-ID <rcZRo-4pd-11@gated-at.bofh.it> (permalink)
References (6 earlier) <rcL22-2Nm-19@gated-at.bofh.it> <rcMKu-3W2-9@gated-at.bofh.it> <rcV1o-1e9-21@gated-at.bofh.it> <rcYBY-3qp-9@gated-at.bofh.it> <rcZom-3Yy-23@gated-at.bofh.it>
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On Tue, 2016-03-15 at 16:47 +0100, Borislav Petkov wrote:
> On Tue, Mar 15, 2016 at 09:43:15AM -0600, Toshi Kani wrote:
> > > Please use on init paths boot_cpu_has(X86_FEATURE_PAT) and on fast
> > > paths static_cpu_has(X86_FEATURE_PAT). No more of that cpu_has_XXX
> > > ugliness.
> > 
> > 'cpu_has_pat' is defined as 'boot_cpu_has(X86_FEATURE_PAT)'.  Do you
> > mean it should explicitly use 'boot_cpu_has(X86_FEATURE_PAT)'?
> 
> No, read what I said.
> 
> We use boot_cpu_has(<feature_bit>) on slow paths (i.e., init, bootup,
> etc), where speed is not that important. static_cpu_has(<feature_bit>)
> is an optimized version which should be used in hot paths.

Yes, I understand that part.  Let me rephrase my question.

This PAT code is on init paths and speed is not that important.  So, it
needs to use 'boot_cpu_has()' here.  'cpu_has_pat' is defined
as boot_cpu_has(X86_FEATURE_PAT), and hence it uses boot_cpu_has() already.
 
While cpu_has_pat is the same as boot_cpu_has(X86_FEATURE_PAT), cpu_has_XXX
should not be used.  So, this code needs to be changed to use
boot_cpu_has(X86_FEATURE_PAT) directly.

Is this right?

Thanks,
-Toshi

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Thread

[PATCH 0/2] Refactor MTRR and PAT initializations Toshi Kani <toshi.kani@hpe.com> - 2016-03-11 05:00 +0100
  [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Toshi Kani <toshi.kani@hpe.com> - 2016-03-11 05:00 +0100
    Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Borislav Petkov <bp@alien8.de> - 2016-03-11 10:20 +0100
      Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT  table Toshi Kani <toshi.kani@hpe.com> - 2016-03-11 16:40 +0100
        Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Borislav Petkov <bp@alien8.de> - 2016-03-11 17:00 +0100
          Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT  table Toshi Kani <toshi.kani@hpe.com> - 2016-03-11 19:40 +0100
            Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Borislav Petkov <bp@alien8.de> - 2016-03-12 13:00 +0100
              Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT  table Toshi Kani <toshi.kani@hpe.com> - 2016-03-14 21:50 +0100
                Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Borislav Petkov <bp@alien8.de> - 2016-03-15 12:10 +0100
                Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT  table Toshi Kani <toshi.kani@hpe.com> - 2016-03-15 22:10 +0100
              Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-03-15 01:30 +0100
                Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT  table Toshi Kani <toshi.kani@hpe.com> - 2016-03-15 03:20 +0100
                Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Borislav Petkov <bp@alien8.de> - 2016-03-15 12:10 +0100
                Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT  table Toshi Kani <toshi.kani@hpe.com> - 2016-03-15 16:00 +0100
                Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Borislav Petkov <bp@alien8.de> - 2016-03-15 16:50 +0100
                Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT  table Toshi Kani <toshi.kani@hpe.com> - 2016-03-15 17:20 +0100
                Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Borislav Petkov <bp@alien8.de> - 2016-03-15 17:40 +0100
                Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-03-15 22:40 +0100
  [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Toshi Kani <toshi.kani@hpe.com> - 2016-03-11 05:00 +0100
    Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Ingo Molnar <mingo@kernel.org> - 2016-03-11 10:10 +0100
      Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Ingo Molnar <mingo@kernel.org> - 2016-03-11 10:20 +0100
        Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Toshi Kani <toshi.kani@hpe.com> - 2016-03-11 18:50 +0100
          Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Ingo Molnar <mingo@kernel.org> - 2016-03-12 17:20 +0100
            Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Toshi Kani <toshi.kani@hpe.com> - 2016-03-14 20:00 +0100
          Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code "Luis R. Rodriguez" <mcgrof@suse.com> - 2016-03-15 00:00 +0100
            Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Toshi Kani <toshi.kani@hpe.com> - 2016-03-15 00:50 +0100
              Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Borislav Petkov <bp@suse.de> - 2016-03-15 17:00 +0100
    Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Borislav Petkov <bp@alien8.de> - 2016-03-11 10:30 +0100
      Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Toshi Kani <toshi.kani@hpe.com> - 2016-03-11 19:10 +0100
        Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-03-11 23:20 +0100
          Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Toshi Kani <toshi.kani@hpe.com> - 2016-03-12 00:10 +0100
            Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-03-12 00:40 +0100
              Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Toshi Kani <toshi.kani@hpe.com> - 2016-03-12 01:30 +0100
                Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-03-15 01:20 +0100
                Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Toshi Kani <toshi.kani@hpe.com> - 2016-03-16 00:00 +0100
                Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-03-16 00:30 +0100

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