linux-kernel - Re: [patch v2 1/2] x86,module: Detect VMX modules and disable Split-Lock-Detect

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Message-ID: <20200402185148.GL20730@hirez.programming.kicks-ass.net>
Date:   Thu, 2 Apr 2020 20:51:48 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Xiaoyao Li <xiaoyao.li@...el.com>,
        LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        "Kenneth R. Crudup" <kenny@...ix.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Jessica Yu <jeyu@...nel.org>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Nadav Amit <namit@...are.com>,
        Thomas Hellstrom <thellstrom@...are.com>,
        Tony Luck <tony.luck@...el.com>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [patch v2 1/2] x86,module: Detect VMX modules and disable
 Split-Lock-Detect

On Thu, Apr 02, 2020 at 10:51:28AM -0700, Sean Christopherson wrote:
> On Thu, Apr 02, 2020 at 07:34:35PM +0200, Thomas Gleixner wrote:
> > Aside of that I'm still against the attempt of proliferating crap,
> > i.e. disabling it because the host is triggering it and then exposing it
> > to guests. The above does not change my mind in any way. This proposal
> > is still wrong.
> 
> Eh, I still think the "off in host, on in guest" is a legit scenario for
> debug/development/testing, but I agree that the added complexity doesn't
> justify the minimal benefits versus sld_warn.

Off in host on in guest seems utterly insane to me. Why do you care
about that?

That's like building a bridge with rotten timber.