linux-kernel - Re: [PATCH v2 3/4] drm/ttm, drm/vmwgfx: Correctly support support AMD memory encryption

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <6d0fafcc-b596-481b-7b22-1f26f0c02c5c@intel.com>
Date:   Tue, 3 Sep 2019 12:55:29 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Daniel Vetter <daniel@...ll.ch>
Cc:     Thomas Hellström (VMware) 
        <thomas_os@...pmail.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        pv-drivers@...are.com,
        VMware Graphics <linux-graphics-maintainer@...are.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Tom Lendacky <thomas.lendacky@....com>,
        Thomas Hellstrom <thellstrom@...are.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Christian König <christian.koenig@....com>
Subject: Re: [PATCH v2 3/4] drm/ttm, drm/vmwgfx: Correctly support support AMD
 memory encryption

On 9/3/19 12:51 PM, Daniel Vetter wrote:
>> The thing we need to stop is having mixed encryption rules under one VMA.
> The point here is that we want this. We need to be able to move the
> buffer between device ptes and system memory ptes, transparently,
> behind userspace back, without races. And the fast path (which is "no
> pte exists for this vma") must be real fast, so taking mmap_sem and
> replacing the vma is no-go.

So, when the user asks for encryption and we say, "sure, we'll encrypt
that", then we want the device driver to be able to transparently undo
that encryption under the covers for device memory?  That seems suboptimal.

I'd rather the device driver just say: "Nope, you can't encrypt my VMA".
 Because that's the truth.