Message-ID: <1457641451.15454.561.camel@hpe.com>
Subject: Re: runtime regression with "x86/mm/pat: Emulate PAT when it is
 disabled"
From: Toshi Kani <toshi.kani@hpe.com>
To: Borislav Petkov <bp@suse.de>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>,
        Richard Purdie <richard.purdie@linuxfoundation.org>,
        Toshi Kani <toshi.kani@hp.com>,
        Bruce Ashfield <bruce.ashfield@windriver.com>,
        "Hart, Darren" <darren.hart@intel.com>,
        "saul.wold" <saul.wold@intel.com>, linux-kernel@vger.kernel.org
Date: Thu, 10 Mar 2016 13:24:11 -0700
In-Reply-To: <20160310192053.GD2194@pd.tnic>
References: <1457366596.15454.281.camel@hpe.com>
	 <20160307210852.GC26051@windriver.com> <1457393912.15454.419.camel@hpe.com>
	 <20160307235328.GD26051@windriver.com> <1457398578.15454.421.camel@hpe.com>
	 <1457400913.15454.435.camel@hpe.com> <20160310144250.GG23251@windriver.com>
	 <1457628591.15454.542.camel@hpe.com> <20160310172029.GA2194@pd.tnic>
	 <1457640261.15454.551.camel@hpe.com> <20160310192053.GD2194@pd.tnic>
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On Thu, 2016-03-10 at 20:20 +0100, Borislav Petkov wrote:
> On Thu, Mar 10, 2016 at 01:04:21PM -0700, Toshi Kani wrote:
> > I will send a patch that sets PAT disabled when MTRR is disabled.  This
> > will solve the Paul's issue.  His qemu32 model does not support PAT,
> > either.
> 
> It does, see my other mail. We need to figure out first why is
> pat_init() being called as part of MTRR setup.

I am not familiar with PPRO_FEATURES, but shouldn't 'flags' in
/proc/cpuinfo show "pat" when X86_FEATURE_PAT is set?

pat_init() is being called as part of MTRR setup because PAT initialization
requires the same CPU rendezvous operation implemented in the MTRR code.

Thanks,
-Toshi