linux-kernel - Re: [RFC PATCH v2 19/20] x86: Access the setup data through debugfs un-encrypted

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Message-ID: <20160916071147.GB23229@nazgul.tnic>
Date:   Fri, 16 Sep 2016 09:11:47 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Tom Lendacky <thomas.lendacky@....com>
Cc:     linux-arch@...r.kernel.org, linux-efi@...r.kernel.org,
        kvm@...r.kernel.org, linux-doc@...r.kernel.org, x86@...nel.org,
        linux-kernel@...r.kernel.org, kasan-dev@...glegroups.com,
        linux-mm@...ck.org, iommu@...ts.linux-foundation.org,
        Radim Krčmář <rkrcmar@...hat.com>,
        Arnd Bergmann <arnd@...db.de>,
        Jonathan Corbet <corbet@....net>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        Joerg Roedel <joro@...tes.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Ingo Molnar <mingo@...hat.com>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Alexander Potapenko <glider@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [RFC PATCH v2 19/20] x86: Access the setup data through debugfs
 un-encrypted

On Thu, Sep 15, 2016 at 12:08:04PM -0500, Tom Lendacky wrote:
> The problem is that this physical address does not contain the
> encryption bit, and even if it did, it wouldn't matter.  The __va()
> define creates a virtual address that will be mapped as encrypted given
> the current approach (which is how I found this).  It's only ioremap()
> that would create a mapping without the encryption attribute and since
> this is unencrypted data it needs to be access accordingly.

I see. So since this is not obvious, please add this explanation to maybe

Documentation/x86/amd-memory-encryption.txt

and point in there to an example or so so.

Thanks.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
--