From: Toshi Kani <toshi.kani@hpe.com>
To: Borislav Petkov <bp@alien8.de>
Cc: "mingo@kernel.org" <mingo@kernel.org>,
"hpa@zytor.com" <hpa@zytor.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"mcgrof@suse.com" <mcgrof@suse.com>,
"jgross@suse.com" <jgross@suse.com>,
"paul.gortmaker@windriver.com" <paul.gortmaker@windriver.com>,
"x86@kernel.org" <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table
Date: Tue, 15 Mar 2016 16:02:00 -0600 [thread overview]
Message-ID: <1458079320.6393.376.camel@hpe.com> (raw)
In-Reply-To: <20160315110005.GB4559@pd.tnic>
On Tue, 2016-03-15 at 12:00 +0100, Borislav Petkov wrote:
> On Mon, Mar 14, 2016 at 03:37:23PM -0600, Toshi Kani wrote:
> > Your patch is a simplified version of mine. So, yes, it fixes the
> > Paul's issue, but it does not address other issues that my patchset
> > also addressed. In specific, I think your patch has the following
> > issues.
>
> You couldnt've structured your reply better: remember how I split a
> convoluted patch of yours already? A patch which was trying to do a
> bunch of things in one go.
>
> The situation here is the same. You need to do *one* *logical*
> *non-trivial* thing in a patch. If there's something else that needs to
> be done, add it in a *separate* patch which explains why that new change
> is needed.
Got it!
> > - pat_disable() is now callable from other modules. So, it needs to
> > check with boot_cpu_done. We cannot disable PAT once it is initialized.
>
> That should be a separate patch which explains *why* the change is being
> done.
>
> > - mtrr_bp_init() needs to check with mtrr_enabled() when it
> > calls mtrr_pat_setup_bp(). Otherwise, PAT is left initialized on BSP
> > only when MTRR is disabled by its MSR. In your patch, mtrr_bp_init()
> > calls pat_setup() again, but it does not help since boot_cpu_done is
> > set.
>
> The code which you carved out from get_mtrr_state() didn't check
> mtrr_enabled() before. That needs to be another patch *again* with
> explanations.
>
> > - When PAT is disabled in CPU feature, pat_bsp_init() calls
> > pat_disable() and returns. However, it does not initialize a PAT table
> > by calling pat_init_cache_modes().
>
> Yet another patch.
>
> > - When CONFIG_MTRR is unset, it does not call pat_setup().
>
> Aaaand... can you guess what I'm going to say here?
>
> I hope it is coming across as I intend it: please use my hunk to do a
> single fix and then prepare all those changes above in separate patches
> with explanations:
Unfortunately, this single fix will break Xen. So, I think we will need to
make a few enhancements first before making the fix.
> "Problem is A. We need to do B. I'm doing it/I'm doing C because."
>
> Ok?
Yes, I will try to separate the patches to change one logical thing at a
time.
Thanks,
-Toshi
next prev parent reply other threads:[~2016-03-15 21:09 UTC|newest]
Thread overview: 49+ 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 [this message]
2016-03-15 0:29 ` Luis R. Rodriguez
2016-03-15 3:11 ` Toshi Kani
2016-03-15 11:01 ` Borislav Petkov
2016-03-15 15:43 ` Toshi Kani
2016-03-15 15:47 ` Borislav Petkov
2016-03-15 17:11 ` Toshi Kani
2016-03-15 16:33 ` Borislav Petkov
2016-03-15 21:31 ` 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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