From: Andi Kleen <ak@linux.intel.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jiri Kosina <jikos@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Andrea Arcangeli <aarcange@redhat.com>,
David Woodhouse <dwmw@amazon.co.uk>,
Tim Chen <tim.c.chen@linux.intel.com>,
Casey Schaufler <casey.schaufler@intel.com>,
Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
"the arch\/x86 maintainers" <x86@kernel.org>,
stable@vger.kernel.org
Subject: Re: STIBP by default.. Revert?
Date: Sun, 18 Nov 2018 15:56:10 -0800 [thread overview]
Message-ID: <871s7i0wkl.fsf@linux.intel.com> (raw)
In-Reply-To: <CAHk-=wjo9==zLdUuZkCgMx1YBUTpZkD3NnLBPDf7Fw388z5Y6g@mail.gmail.com> (Linus Torvalds's message of "Sun, 18 Nov 2018 14:36:09 -0800")
Linus Torvalds <torvalds@linux-foundation.org> writes:
> On Sun, Nov 18, 2018 at 2:17 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 don't think the code needs to be reverted, but the *behavior* of
> just unconditionally enabling STIBP needs to be reverted.
Actually I think it should be reverted. Yes of course opt-in
is needed.
But also when you opt-in it doesn't make sense to set STIBP
when the sibling is running the same security context, which
is actually a common case. So to even use it properly you would
need some scheduler support to detect these cases and only
enable it then with opt-in. These patches didn't even try to tackle
this problem.
-Andi
next prev parent reply other threads:[~2018-11-18 23:56 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-18 20:36 STIBP by default.. Revert? Linus Torvalds
2018-11-18 21:49 ` Jiri Kosina
2018-11-18 21:59 ` Willy Tarreau
2018-11-18 22:00 ` Linus Torvalds
2018-11-18 22:17 ` Jiri Kosina
2018-11-18 22:35 ` Dave Hansen
2018-11-18 22:36 ` Tony Luck
2018-11-18 22:36 ` Linus Torvalds
2018-11-18 22:55 ` Tim Chen
2018-11-18 23:56 ` Andi Kleen [this message]
2018-11-18 22:40 ` Tim Chen
2018-11-18 23:58 ` Andi Kleen
2018-11-19 3:48 ` Willy Tarreau
2018-11-19 12:49 ` Thomas Gleixner
2018-11-18 23:01 ` Jiri Kosina
2018-11-18 23:04 ` Arjan van de Ven
2018-11-20 15:27 ` Jiri Kosina
2018-11-20 23:43 ` Arjan van de Ven
2018-11-19 8:38 ` Ingo Molnar
2018-11-19 8:43 ` Jiri Kosina
2018-11-20 15:20 ` Jiri Kosina
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