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Wed, 31 Jan 2024 16:00:25 -0500 X-MC-Unique: 7QAU2XYdMgKue_crt0yw-Q-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id AB91B38143B5; Wed, 31 Jan 2024 21:00:21 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.72]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4BD39492BE2; Wed, 31 Jan 2024 21:00:20 +0000 (UTC) Date: Wed, 31 Jan 2024 21:00:18 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Kuppuswamy Sathyanarayanan Cc: Dan Williams , Nikolay Borisov , linux-coco@lists.linux.dev, x86@kernel.org, dave.hansen@linux.intel.com, dionnaglaze@google.com, dan.middleton@linux.intel.com Subject: Re: [PATCH] virt: tdx-guest: Deprecate legacy IOCTL-based interface for quote generation Message-ID: Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= References: <20240124093858.1818497-1-nik.borisov@suse.com> <65baa477b8da8_37ad29436@dwillia2-xfh.jf.intel.com.notmuch> <59f268c4-8491-4256-8766-664a8ee0ffd8@linux.intel.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <59f268c4-8491-4256-8766-664a8ee0ffd8@linux.intel.com> User-Agent: Mutt/2.2.12 (2023-09-09) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.10 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline On Wed, Jan 31, 2024 at 12:44:46PM -0800, Kuppuswamy Sathyanarayanan wrote: > > On 1/31/24 11:50 AM, Dan Williams wrote: > > Kuppuswamy Sathyanarayanan wrote: > >> + Dan Middleton > >> > >> Hi Boris, > >> > >> On 1/24/24 1:38 AM, Nikolay Borisov wrote: > >>> IOCTL based interface was the natural choice for interacting with the > >>> quote generation machine at a time when there wasn't anything better. > >>> Fortunately, now we have a vendor-agnostic, configfs-based one which > >>> obviates the need to have the IOCTL-based interface. > >>> > >>> Gate the relevant code behind a Kconfig option, clearly marking it as > >>> deprecated as well as introduce a runtime warning. > >>> > >>> Signed-off-by: Nikolay Borisov > >>> --- > >> In the following thread, Dan Middleton raised a point about this interface > >> being used for local attestation use cases. > >> > >> https://lore.kernel.org/all/ZbAaKAh-230Hj4BF@redhat.com/T/#m691dae9a7833a35552cafb597c838df9c2ed5f3a > >> > >> Currently, the configfs-based ABI does not support the local attestation use cases. > > What are local attestation use cases, and what happens if Linux does not > > provide a local attestation interface and standardizes on remotely > > attestable as the standard? > > > Local attestation is used by one TD on the same platform to prove to another TD > in the same platform about its identity. It is mainly used in cases where a TD provides > some special services required by other TDs. Since they are all in the same platform, > there is no need for a 3rd party verifier or Quoting service. It can use the verifiable MAC > to check the correctness of the TD. As an example of where this might be needed, consider supporting a vTPM in TDX. The TPM impl would likely be run in a separate service TD, and need to be locally attested by the primary TD, to establish trust in the vTPM. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|