From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 5E95F31E834; Sat, 17 Oct 2026 21:14:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792271665; cv=none; b=p9AfgzQA2XbE38Vk1cyqudNew9pflTzt6d3ayoBpYPcg2evqclF+1S3ukG0eWmC8gDxZKWUoTyuZsV14T7OgzfVNIxFp9YntZeMqZ7TnMUuyHANJVhCid5sYojo2kkq3p+C9NvaQ/Cnw5EBieDuY7s37Qz0Ymsa3i4Kg/qpstkc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792271665; c=relaxed/simple; bh=uwQYxTDhT24TVmXMpGbl8/96piiC56dPsU977K30FL4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=UqYfZPsBk2314cEuxZ0M4DPJz0wUjppH5pYmX4gNLnG18lL44s244h602Il/uCmJPN7Ct0ZZatcfJDPhSUJ4bHn0gkvDlAdMC/76U/qFQ0O+PsokvNvOEPzjeeirKDk3Ym/vDKRYXXT43ClAJkn7XVu6w3McdRvR0qI18Ck6ytc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MvbzIyL0; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MvbzIyL0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6B82E1F000C4; Sat, 17 Oct 2026 21:14:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792271663; bh=FKO4CvfP/4EzoFbPAE+XxKnikN9D8rSYpkJhdJvI2YY=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=MvbzIyL0+uVY1WLiysuCtcLfA7PbeMDJpKuvDJe215wvkhLzeUV1GMQmQqgs1zvRu XZGJ97HAv7I5lhtf9N7+ly81oScPwT85cZ1RVqcf1RmqETY7Z63C87hD/+H1sf4SS+ 10TGoybaPW9G/6/ODl73rFLo9IwJa77No3hZ9stqenEnyRNqJx7b6thQu+UphD5jqG 57LfY1kqT2f6UQ5IQ0rR52PYJPDQ9wVGss7xlVaN+oUrXWkX1dNmjExBWsO+yPEqJ1 3WacyFkzF5oeq43mEuLsz0jclKaDKuQjFAnglzjM+aNlt4E60uFgnfLNNrwnePSRWD dz4W+vAVVEgVg== Date: Sun, 18 Oct 2026 00:14:20 +0300 From: Jarkko Sakkinen To: Jason Gunthorpe Cc: Dionna Glaze , Jiri Pirko , linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, x86@kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, david.quigley@intel.com, lukas@wunner.de, ksinyuk@kernel.org, rodrigo.vivi@intel.com, cedric.xing@intel.com, sameo@meta.com, James.Bottomley@hansenpartnership.com, aik@amd.com, jpiotrowski@nvidia.com, qinkun@google.com, pgonda@google.com, jic23@kernel.org, alistair.francis@wdc.com, ankita@nvidia.com, suzuki.poulose@arm.com, kas@kernel.org, rick.p.edgecombe@intel.com, elena.reshetova@intel.com, dave.hansen@linux.intel.com, sathyanarayanan.kuppuswamy@linux.intel.com, peter.fang@intel.com Subject: Re: [PATCH RFC 00/20] attestation: Add a common subsystem and TDX support Message-ID: References: <20261015145053.3664509-1-jiri@resnulli.us> <20261016234354.GA664420@nvidia.com> <20261017205557.GN13920@nvidia.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261017205557.GN13920@nvidia.com> On Sat, Oct 17, 2026 at 05:55:57PM -0300, Jason Gunthorpe wrote: > On Sat, Oct 17, 2026 at 10:06:04PM +0300, Jarkko Sakkinen wrote: > > On Sat, Oct 17, 2026 at 11:16:07AM -0700, Dionna Glaze wrote: > > > +Jarkko > > > The TPM driver is pretty entrenched and heavily used by different user > > > space applications, so it seems really ambitious to bundle in TPM > > > here. > > > > This is something on the table thanks to Trenchboot and its early boot > > code. > > I've proposed that there be no early TPM in the Linux DRTM > implementation. The trampoline would just do a bit of additional work > with its existing TPM code before it reaches Linux. > > https://lore.kernel.org/all/20261016165135.GA494690@nvidia.com/ Maybe really would want to see a PoC of this. > > My intention with attestation subsystem: tpm and DRTM is to follow the > ARM design and get ACPI up enough to reach a HW driver. Attestation > subsystem will multiplex the DRTM "PCR" logging to which ever ROT that > DRTM launch selected. This is another reason why I dont like early TPM > because it turns from just early TPM, already hard, into > early-every-ROT which is much worse. Earlyboot code could be done with just C by having TCG compatible device parts in a "TIS lib" and "CRB lib" but yeah, this will inevitably hit into having to upscale hardware over TCG MMIO. So yeah, I think I get the negatives. This is what bothers me a bit also in Trenchboot patch set. Arbitrary context dependent hardware support for TPM does sound a bit risky... > > I view all the stuff you are listing to make tpm early work as too > difficult compared to just having the trampoline do it since it > already must have a TPM extend operation inside it. OK, thanks for sharing this, and I'm not arguing against this. > > Jason Br, Jarkko