Subject: Re: [PATCH 1/4] x86/cpufeature: Add User-Mode Instruction Prevention
 definitions
To: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>,
        Andy Lutomirski <luto@amacapital.net>
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Cc: Ingo Molnar <mingo@kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        X86 ML <x86@kernel.org>,
        "linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
        Andy Lutomirski <luto@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Borislav Petkov <bp@suse.de>, Brian Gerst <brgerst@gmail.com>,
        Chen Yucong <slaoub@gmail.com>, Chris Metcalf <cmetcalf@mellanox.com>,
        Fenghua Yu <fenghua.yu@intel.com>, Huang Rui <ray.huang@amd.com>,
        Jiri Slaby <jslaby@suse.cz>, Jonathan Corbet <corbet@lwn.net>,
        "Michael S . Tsirkin" <mst@redhat.com>,
        Paul Gortmaker <paul.gortmaker@windriver.com>,
        Peter Zijlstra <peterz@infradead.org>,
        "Ravi V . Shankar" <ravi.v.shankar@intel.com>,
        Shuah Khan <shuah@kernel.org>, Vlastimil Babka <vbabka@suse.cz>
From: Dave Hansen <dave.hansen@linux.intel.com>
Message-ID: <0464c3f4-3810-14f5-e1bb-45eec14a7e63@linux.intel.com>
Date: Thu, 10 Nov 2016 09:09:43 -0800
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On 11/09/2016 07:24 PM, Ricardo Neri wrote:
> On Wed, 2016-11-09 at 03:02 -0800, Andy Lutomirski wrote:
...
>> > What I mean is: why does this need a config option at all?
> I intended this feature to be configurable at build time in case someone
> wants to build a kernel without it; similar to other features such as
> SMAP. Is this not needed? Should Linux be built with this feature always
> enabled?

I think marking these features with their own CONFIG's is a really good
idea.  It helps the tinification effort.  It's also nice for folks that
might want to turn all the Intel features off because they're running on
AMD or something.

We don't necessarily need prompts for *everything*, but I can't imagine
just slapping the code in without #ifdefs of any kind.