From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andi Kleen <ak@linux.intel.com>
Subject: Re: [RFC 09/10] x86/enter: Create macros to restrict/unrestrict
 Indirect Branch Speculation
Date: Tue, 23 Jan 2018 14:49:56 -0800
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Cc: "Woodhouse, David" <dwmw@amazon.co.uk>,
        Andy Lutomirski <luto@amacapital.net>,
        KarimAllah Ahmed <karahmed@amazon.de>,
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        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "H . Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
        Janakarajan Natarajan <Janakarajan.Natarajan@amd.com>,
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        Jun Nakajima <jun.nakajima@intel.com>,
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To: Tom Lendacky <thomas.lendacky@amd.com>
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> Not sure.  Maybe to start, the answer might be to allow it to be set for
> the ultra-paranoid, but in general don't enable it by default.  Having it
> enabled would be an alternative to someone deciding to disable SMT, since
> that would have even more of a performance impact.

I agree. A reasonable strategy would be to only enable it for
processes that have dumpable disabled. This should be already set for
high value processes like GPG, and allows others to opt-in if
they need to.

-Andi