From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7A27543AC0 for ; Thu, 1 Feb 2024 08:15:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706775329; cv=none; b=Wpcngel3Kb9qnU/bb+8wGQs4FlhqUHNsQ4okzrQy7B6zMibNh1ThQ1Pri7s394VmWaooyKfqnLwjCZ0twN8MhK7hUeD5v1fbD97LVL+gQNFp05XdFLsBQrvbxFNav2xSkvY1EzI6KWZ1adFs80VYR4c0liSuqv/E3PzK5/kgcUg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706775329; c=relaxed/simple; bh=+hl3MulbJIcZd3qZtP9hoi8toi8Bac3oc+EfxJWLOIU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: In-Reply-To:Content-Type:Content-Disposition; b=LEA8wryh0mkdKfyX7kZyXk/796PfaZLmF8k/XN0k0iwHl1kCPB25m0P51AzHdCD5WG/LpgyMUh77Pm1NlgBv5XAeTZa5AdHyvlTAKzFUbKEnEdnWJa52mr/rqUcCgoOqOlKw0YxkB+Ah2NJO6fqERLmc4q24eLI0z/9E//IJ84U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=TXGnOU6U; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="TXGnOU6U" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1706775326; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=bhZhfPqoa9HPDA4Ap1gFQwV4Q6xA+en5rvnxodzvMMc=; b=TXGnOU6Ub8MNQjbt/IJqFsFpDit64vMjzVyhomGgUBkLcn1DOIFF1DsSe2ie5SKyt5p/Pk jAG4eHLMN6LnWHe9V83TVCWpLKgzPzeHIlKTImqlBgRVUP1HGmrZ8WIri6T0esDRiKHkA9 NIGSMCu+aEF8sYANBQ5bB82m4lzlI0A= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-414-W6RdqT-oO96k_i7uFa_eFg-1; Thu, 01 Feb 2024 03:15:22 -0500 X-MC-Unique: W6RdqT-oO96k_i7uFa_eFg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (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 3C24D1C06905; Thu, 1 Feb 2024 08:15:22 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.46]) by smtp.corp.redhat.com (Postfix) with ESMTPS id ECA77C0FDEF; Thu, 1 Feb 2024 08:15:20 +0000 (UTC) Date: Thu, 1 Feb 2024 08:15:14 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Dan Williams Cc: Kuppuswamy Sathyanarayanan , 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> <65bab7cdc650e_37ad294e1@dwillia2-xfh.jf.intel.com.notmuch> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <65bab7cdc650e_37ad294e1@dwillia2-xfh.jf.intel.com.notmuch> User-Agent: Mutt/2.2.12 (2023-09-09) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.8 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit On Wed, Jan 31, 2024 at 01:12:45PM -0800, Dan Williams wrote: > Daniel P. Berrangé wrote: > > 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. > > Service TDs are in active deployment? How does that work? A tenant pays > the fees to host 2 VMs? Is that more economical than just communicating > the remote verifier? Not trying to be argumentative just trying to get > to the root of the question "why Linux must care about local > attestation". Any VM you buy has host resource overhead beyond the VM's declared resources, and whether you realize it or not, as a user you are paying for this extra resource consumption. With KVM today, vTPM will involve each VM having a separate swtpm process running alongside QEMU in the host, and of course QEMU itself has resource consumption which can be fairly significant. A Cloud provider will have to take account of the additional per-VM overheads when calculating their potential host capacity for running VMs & thus setting their VM price. In a TDX scenario this separate swtpm turns into something that runs inside a minimal TDVM instead. The RAM overhead may be larger than with swtpm, but for a cloud provider its merely one more factor to take account of when setting their price vs host capacity. 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 :|