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Date: Sat, 6 Jan 2018 22:21:04 +0100 (CET)
From: Thomas Gleixner <tglx@linutronix.de>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk>,
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        Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH 06/18] x86, barrier: stop speculation for failed
 access_ok
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On Sat, 6 Jan 2018, Alexei Starovoitov wrote:
> So how about we do array_access() macro similar to above by default
> with extra CONFIG_ to convert it to lfence ?
> Why default to AND approach instead of lfence ?
> Because the kernel should still be usable. If security
> sacrifices performance so much such security will be turned off.
> Ex: kpti suppose to add 5-30%. If it means 10% on production workload
> and the datacenter capacity cannot grow 10% overnight, kpti will be off.

That's the decision and responsibility of the person who disables it.

Thanks,

	tglx