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Date:   Thu, 7 Oct 2021 17:17:54 +0100
From:   "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To:     Dave Hansen <dave.hansen@intel.com>
Cc:     Dov Murik <dovmurik@linux.ibm.com>, linux-efi@vger.kernel.org,
        Borislav Petkov <bp@suse.de>,
        Ashish Kalra <ashish.kalra@amd.com>,
        Brijesh Singh <brijesh.singh@amd.com>,
        Tom Lendacky <thomas.lendacky@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>,
        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 v2 4/4] virt: Add sev_secret module to expose
 confidential computing secrets
Message-ID: <YV8dsl+qgbIH6z8F@work-vm>
References: <20211007061838.1381129-1-dovmurik@linux.ibm.com>
 <20211007061838.1381129-5-dovmurik@linux.ibm.com>
 <7e2a4595-3f9c-6d65-34e3-af7c1d6da196@intel.com>
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* Dave Hansen (dave.hansen@intel.com) wrote:
> On 10/6/21 11:18 PM, Dov Murik wrote:
> > +static int sev_secret_map_area(void)
> > +{
> > +	struct sev_secret *s = sev_secret_get();
> > +	struct linux_efi_coco_secret_area *secret_area;
> > +	u32 secret_area_size;
> > +
> > +	if (efi.coco_secret == EFI_INVALID_TABLE_ADDR) {
> > +		pr_err("Secret area address is not available\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	secret_area = memremap(efi.coco_secret, sizeof(*secret_area), MEMREMAP_WB);
> > +	if (secret_area == NULL) {
> > +		pr_err("Could not map secret area header\n");
> > +		return -ENOMEM;
> > +	}
> 
> There doesn't seem to be anything truly SEV-specific in here at all.
> Isn't this more accurately called "efi_secret" or something?  What's to
> prevent Intel or an ARM vendor from implementing this?

I don't think anything; although the last discussion I remember on list
with Intel was that Intel preferred some interface with an ioctl to read
the secrets and stuff.  I'm not quite sure if the attestation/secret
delivery order makes sense with TDX, but if it does, then if you could
persuade someone to standardise on this it would be great.

Dave

-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK