Date:   Fri, 7 Jan 2022 12:59:09 +0100
From:   Borislav Petkov <bp@suse.de>
To:     "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc:     Dov Murik <dovmurik@linux.ibm.com>,
        Brijesh Singh <brijesh.singh@amd.com>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        linux-efi@vger.kernel.org, Ashish Kalra <ashish.kalra@amd.com>,
        Ard Biesheuvel <ardb@kernel.org>,
        James Morris <jmorris@namei.org>,
        "Serge E. Hallyn" <serge@hallyn.com>,
        Andi Kleen <ak@linux.intel.com>,
        Greg KH <gregkh@linuxfoundation.org>,
        Andrew Scull <ascull@google.com>,
        Dave Hansen <dave.hansen@intel.com>,
        James Bottomley <jejb@linux.ibm.com>,
        Tobin Feldman-Fitzthum <tobin@linux.ibm.com>,
        Jim Cadden <jcadden@ibm.com>,
        Daniele Buono <dbuono@linux.vnet.ibm.com>,
        linux-coco@lists.linux.dev, linux-security-module@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 0/5] Allow guest access to EFI confidential computing
 secret area
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On Wed, Jan 05, 2022 at 08:07:04PM +0000, Dr. David Alan Gilbert wrote:
> I thought I saw something in their patch series where they also had a
> secret that got passed down from EFI?

Probably. I've seen so many TDX patchsets so that I'm completely
confused what is what.

> As I remember they had it with an ioctl and something; but it felt to
> me if it would be great if it was shared.

I guess we could try to share

https://lore.kernel.org/r/20211210154332.11526-28-brijesh.singh@amd.com

for SNP and TDX.

> I'd love to hear from those other cloud vendors; I've not been able to
> find any detail on how their SEV(-ES) systems actually work.

Same here.

> However, this aims to be just a comms mechanism to pass that secret;
> so it's pretty low down in the stack and is there for them to use -
> hopefully it's general enough.

Exactly!

> (An interesting question is what exactly gets passed in this key and
> what it means).
> 
> All the contentious stuff I've seen seems to be further up the stack - like
> who does the attestation and where they get the secrets and how they
> know what a valid measurement looks like.

It would be much much better if all the parties involved would sit down
and decide on a common scheme so that implementation can be shared but
getting everybody to agree is likely hard...

-- 
Regards/Gruss,
    Boris.

SUSE Software Solutions Germany GmbH, GF: Ivo Totev, HRB 36809, AG Nürnberg