From: Peter Zijlstra <peterz@infradead.org>
To: "Martin-Éric Racine" <martin-eric.racine@iki.fi>
Cc: Ben Hutchings <ben@decadent.org.uk>,
x86@kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
1017425@bugs.debian.org, stable@vger.kernel.org,
regressions@lists.linux.dev,
Daniel Sneddon <daniel.sneddon@linux.intel.com>,
Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Subject: Re: [PATCH] x86/speculation: Avoid LFENCE in FILL_RETURN_BUFFER on CPUs that lack it
Date: Tue, 30 Aug 2022 14:00:02 +0200 [thread overview]
Message-ID: <Yw37wnE19bAIhhP2@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CAPZXPQeYh_BrZzinsvCjHvd=szAsOXUmkVYS1tJC5vwamx+Wow@mail.gmail.com>
On Tue, Aug 30, 2022 at 02:42:04PM +0300, Martin-Éric Racine wrote:
> Greetings,
>
> On Fri, Aug 19, 2022 at 3:15 PM Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > On Fri, Aug 19, 2022 at 01:38:27PM +0200, Ben Hutchings wrote:
> >
> > > So that puts the whole __FILL_RETURN_BUFFER inside an alternative, and
> > > we can't have nested alternatives. That's unfortunate.
> >
> > Well, both alternatives end with the LFENCE instruction, so I could pull
> > it out and do two consequtive ALTs, but unrolling the loop for i386 is
> > a better solution in that the sequence, while larger, removes the need
> > for the LFENCE.
>
> Have we reached a definitive conclusion on to how to fix this?
https://git.kernel.org/tip/332924973725e8cdcc783c175f68cf7e162cb9e5
next prev parent reply other threads:[~2022-08-30 12:00 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-19 0:33 [PATCH] x86/speculation: Avoid LFENCE in FILL_RETURN_BUFFER on CPUs that lack it Ben Hutchings
2022-08-19 8:47 ` Peter Zijlstra
2022-08-19 11:01 ` Peter Zijlstra
2022-08-19 11:33 ` Martin-Éric Racine
2022-08-19 11:38 ` Ben Hutchings
2022-08-19 12:15 ` Peter Zijlstra
2022-08-30 11:42 ` Martin-Éric Racine
2022-08-30 12:00 ` Peter Zijlstra [this message]
2022-08-30 12:18 ` Martin-Éric Racine
2022-08-30 13:35 ` Bug#1017425: " Salvatore Bonaccorso
2022-08-19 11:02 ` Ben Hutchings
-- strict thread matches above, loose matches on Subject: below --
2022-08-18 23:08 Ben Hutchings
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