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From:   Tony Luck <tony.luck@intel.com>
Date:   Sun, 18 Nov 2018 14:36:02 -0800
Message-ID: <CA+8MBbKqeAFjoqq4G-A8pjDdHoVvXqG1Jv+Q4DTu2ZgZ1Gxvjg@mail.gmail.com>
Subject: Re: STIBP by default.. Revert?
To:     Jiri Kosina <jikos@kernel.org>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>, jpoimboe@redhat.com,
        Andrea Arcangeli <aarcange@redhat.com>, dwmw@amazon.co.uk,
        Andi Kleen <ak@linux.intel.com>, tim.c.chen@linux.intel.com,
        casey.schaufler@intel.com,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        X86-ML <x86@kernel.org>, stable <stable@vger.kernel.org>
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On Sun, Nov 18, 2018 at 2:19 PM Jiri Kosina <jikos@kernel.org> wrote:
> Which gets us back to Tim's fixup patch. Do you still prefer the revert,
> given the existence of that? I think that if Tim's fixup makes it through
> (it's currently missing SECCOMP handling, but that is trivial to add on
> top), it might be the best compromise. We'd also have have to make IBPB
> obey it to be consistent (and get even a few more % of performance back),
> but that's easy as well.

+1 for Tim's patch.  That make us more consistent with how we handled
L1TF (giving the system owner a control knob to decide whether they
want this level of fixup, based on their own analysis of their vulnerability).

-Tony