linux-kernel - Re: [PATCH] Ability to read the MKTME status from userspace

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Message-ID: <20200619132243.GC32683@zn.tnic>
Date:   Fri, 19 Jun 2020 15:22:43 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Daniel Gutson <daniel@...ypsium.com>
Cc:     Dave Hansen <dave.hansen@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>, Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        "David S. Miller" <davem@...emloft.net>,
        Rob Herring <robh@...nel.org>, Tony Luck <tony.luck@...el.com>,
        Rahul Tanwar <rahul.tanwar@...ux.intel.com>,
        Xiaoyao Li <xiaoyao.li@...el.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        linux-kernel@...r.kernel.org, Richard Hughes <hughsient@...il.com>
Subject: Re: [PATCH] Ability to read the MKTME status from userspace

On Fri, Jun 19, 2020 at 10:01:36AM -0300, Daniel Gutson wrote:
> Then the user will not know that he/she could improve the security of the
> system by enabling the feature in the BIOS.

And how is the user going to know from your "module"? AFAICT, your
module loads on any system - not only on ones which have MKTME in CPUID.

> The fact that the CPU has the cap and the BIOS disables it, can
> trigger a prevention action.

I can only venture guesses what "prevention action" is - you'll have to
be more verbose here.

-- 
Regards/Gruss,
    Boris.

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