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

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Message-ID: <20200406152231.GQ20730@hirez.programming.kicks-ass.net>
Date:   Mon, 6 Apr 2020 17:22:31 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        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>,
        Xiaoyao Li <xiaoyao.li@...el.com>,
        Nadav Amit <namit@...are.com>,
        Thomas Hellstrom <thellstrom@...are.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [patch 1/2] x86,module: Detect VMX modules and disable
 Split-Lock-Detect

On Mon, Apr 06, 2020 at 08:18:47AM -0700, Christoph Hellwig wrote:
> On Mon, Apr 06, 2020 at 04:40:20PM +0200, Peter Zijlstra wrote:
> > It is absolutely bonkers, but at the same time we can extend this
> > infrastructure to scan for dubious code patterns we don't want to
> > support. Like for instance direct manipulation of CR4.
> 
> But that is not what this code does - it disables split lock detection.
> If it failed to load the module the whole thing would make a little
> more sense.

If this lives, it'll be to just to fail module loading. IIRC the same
was suggested elsewhere in the thread.