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From: Toshi Kani <toshi.kani@hpe.com>
To: Borislav Petkov <bp@alien8.de>
Cc: "jgross@suse.com" <jgross@suse.com>,
	"boris.ostrovsky@oracle.com" <boris.ostrovsky@oracle.com>,
	"x86@kernel.org" <x86@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"paul.gortmaker@windriver.com" <paul.gortmaker@windriver.com>,
	"Luis R. Rodriguez" <mcgrof@kernel.org>,
	"hpa@zytor.com" <hpa@zytor.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"mingo@kernel.org" <mingo@kernel.org>
Subject: Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table
Date: Tue, 15 Mar 2016 11:11:23 -0600	[thread overview]
Message-ID: <1458061883.6393.359.camel__4676.88677968017$1458058822$gmane$org@hpe.com> (raw)
In-Reply-To: <20160315154731.GD4559@pd.tnic>

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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  parent reply	other threads:[~2016-03-15 16:18 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-11  4:45 [PATCH 0/2] Refactor MTRR and PAT initializations Toshi Kani
2016-03-11  4:45 ` [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Toshi Kani
2016-03-11  9:12   ` Borislav Petkov
2016-03-11 16:27     ` Toshi Kani
2016-03-11 15:54       ` Borislav Petkov
2016-03-11 19:28         ` Toshi Kani
2016-03-12 11:55           ` Borislav Petkov
2016-03-14 21:37             ` Toshi Kani
2016-03-15 11:00               ` Borislav Petkov
2016-03-15 22:02                 ` Toshi Kani
2016-03-15  0:29             ` Luis R. Rodriguez
2016-03-15  3:11               ` Toshi Kani
2016-03-15  3:11               ` Toshi Kani
2016-03-15 11:01                 ` Borislav Petkov
2016-03-15 15:43                   ` Toshi Kani
2016-03-15 15:43                   ` Toshi Kani
2016-03-15 15:47                     ` Borislav Petkov
2016-03-15 15:47                     ` Borislav Petkov
2016-03-15 17:11                       ` Toshi Kani
2016-03-15 16:33                         ` Borislav Petkov
2016-03-15 16:33                         ` Borislav Petkov
2016-03-15 17:11                       ` Toshi Kani [this message]
2016-03-15 11:01                 ` Borislav Petkov
2016-03-15 21:31                 ` Luis R. Rodriguez
2016-03-15 21:31                 ` Luis R. Rodriguez
2016-03-15  0:29             ` Luis R. Rodriguez
2016-03-11  4:45 ` [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Toshi Kani
2016-03-11  9:01   ` Ingo Molnar
2016-03-11  9:13     ` Ingo Molnar
2016-03-11 18:34       ` Toshi Kani
2016-03-12 16:18         ` Ingo Molnar
2016-03-14 19:47           ` Toshi Kani
2016-03-14 22:50         ` Luis R. Rodriguez
2016-03-15  0:37           ` Toshi Kani
2016-03-15 15:56             ` Borislav Petkov
2016-03-16 15:44             ` Joe Lawrence
2016-03-11  9:24   ` Borislav Petkov
2016-03-11 18:57     ` Toshi Kani
2016-03-11 22:17       ` Luis R. Rodriguez
2016-03-11 23:56         ` Toshi Kani
2016-03-11 23:34           ` Luis R. Rodriguez
2016-03-12  1:16             ` Toshi Kani
2016-03-15  0:15               ` Luis R. Rodriguez
2016-03-15 23:48                 ` Toshi Kani
2016-03-15 23:29                   ` Luis R. Rodriguez
2016-03-17 21:56                     ` Toshi Kani
2016-03-18  0:06                       ` Luis R. Rodriguez
2016-03-18 21:35                         ` Toshi Kani
2016-03-29 17:14                           ` Luis R. Rodriguez
2016-03-29 21:46                             ` Toshi Kani
2016-03-29 22:12                               ` Luis R. Rodriguez
2016-03-30  0:16                                 ` Toshi Kani
2016-03-29 23:43                                   ` Luis R. Rodriguez
2016-03-30  1:07                                     ` Toshi Kani
2016-03-30  0:34                                       ` Luis R. Rodriguez
2016-04-09  2:04                       ` Luis R. Rodriguez
2016-04-11 14:30                         ` Toshi Kani

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