linux-kernel - Re: [patch V3 05/11] x86/mm/cpa: Add debug mechanism

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Message-ID: <24b0749f-d472-bd6b-4397-e59e01b3a9df@intel.com>
Date:   Fri, 21 Sep 2018 09:40:36 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, Peter Zijlstra <peterz@...radead.org>,
        Bin Yang <bin.yang@...el.com>,
        Mark Gross <mark.gross@...el.com>
Subject: Re: [patch V3 05/11] x86/mm/cpa: Add debug mechanism

On 09/17/2018 07:29 AM, Thomas Gleixner wrote:
> The whole static protection magic is silently fixing up anything which is
> handed in. That's just wrong. The offending call sites need to be fixed.
> 
> Add a debug mechanism which emits a warning if a requested mapping needs to be
> fixed up. The DETECT debug mechanism is really not meant to be enabled except
> for developers, so limit the output hard to the protection fixups.
...
> +enum cpa_warn {
> +	CPA_PROTECT,
> +	CPA_DETECT,
> +};
> +
> +static const int cpa_warn_level = CPA_PROTECT;

Even if this is intended for developers only, should we also add some
config option here so things like 0day can still get warnings out of this?

Reviewed-by: Dave Hansen <dave.hansen@...el.com>