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Message-ID: <1478665614.2533.4.camel@ranerica-desktop>
Subject: Re: [PATCH 2/4] x86: Prepare vm86 tasks to handle User-Mode
 Instruction Prevention
From: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@amacapital.net>, Ingo Molnar <mingo@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>, "H. Peter Anvin" <hpa@zytor.com>,
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        X86 ML <x86@kernel.org>,
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        Andy Lutomirski <luto@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
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        Chen Yucong <slaoub@gmail.com>, Chris Metcalf <cmetcalf@mellanox.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Fenghua Yu <fenghua.yu@intel.com>, Huang Rui <ray.huang@amd.com>,
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        Paul Gortmaker <paul.gortmaker@windriver.com>,
        "Ravi V . Shankar" <ravi.v.shankar@intel.com>,
        Shuah Khan <shuah@kernel.org>, Vlastimil Babka <vbabka@suse.cz>
Date: Tue, 08 Nov 2016 20:26:54 -0800
In-Reply-To: <20161108170034.GK3117@twins.programming.kicks-ass.net>
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On Tue, 2016-11-08 at 18:00 +0100, Peter Zijlstra wrote:
> > > +       }
> > > +#endif
> > > +
> > 
> > NAK.  If this code is going to exist, it needs to be deeply buried
> in
> > some unlikely if statement that already exists.  There's no good
> > reason to penalize all context switches to support some nonsensical
> > vm86 use case.
> 
> Agreed, now if instead vm86 get to emulate these instructions, this
> all
> magically goes away..

Yes. I agree. I will rework the series and this should not be needed.

Thanks and BR,
Ricardo