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

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Message-ID: <20200402162548.GH20730@hirez.programming.kicks-ass.net>
Date:   Thu, 2 Apr 2020 18:25:48 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Xiaoyao Li <xiaoyao.li@...el.com>
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>,
        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 v2 1/2] x86,module: Detect VMX modules and disable
 Split-Lock-Detect


Learn to trim your replies already!

On Fri, Apr 03, 2020 at 12:20:08AM +0800, Xiaoyao Li wrote:
> On 4/2/2020 11:23 PM, Peter Zijlstra wrote:

> > +bad_module:
> > +	pr_warn("disabled due to VMX in module: %s\n", me->name);
> > +	sld_state = sld_off;
> 
> shouldn't we remove the __ro_after_init of sld_state?

Oh, that's probably a good idea. I can't actually test this due to no
hardware.

> And, shouldn't we clear X86_FEATURE_SPLIT_LOCK_DETECT flag?

Don't think you can do that this late. Also, the hardware has the MSR
and it works, it's just that we should not.