From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.17]) (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 B86E835CBB6 for ; Wed, 11 Feb 2026 21:13:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.17 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770844418; cv=none; b=qCJL8mJWQcDFjuoxTwFB/oEZXqYD8CVywefpTFGD414Y2Nax7kXxyqpZGynozHMf1zAu7rJdMaOG8yOuAVLgnBI2ajunC9xYsuYT3hdgW5YbZ1cOJ7T0Kf9wWSfEvsp6qX4MIFuHx4q/Y3KUFBoycS46qJP8CQ0GxZY+11Xy7ik= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770844418; c=relaxed/simple; bh=IM8DRf4BM6t7hJwwIpXycGoW5I8PziYnxhEVfXHDNcE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=D0zgoYbSeMyGw14xAsI9TYXEPI/SJyGTwCEfqmojsutARqYogH4UlBqe/IHYouk0i6eU4CGQnXZJi2EEP9/eerOt/MHgi7PjlDERL1ll+kHLGvvJtxHqrXM36ncRLUBo4uVJqZWuSH2bcabkmJP2EYDmFrDI0Y/2YhefkfiiM98= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=RyZOI2Z2; arc=none smtp.client-ip=192.198.163.17 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="RyZOI2Z2" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1770844418; x=1802380418; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=IM8DRf4BM6t7hJwwIpXycGoW5I8PziYnxhEVfXHDNcE=; b=RyZOI2Z29gtOugIRZXJASlKD1vXfHR39io9LJlM3BTUnxVP32MbMHuOU AY58PPAJ9aDoF/BE3HukUopkuDeAiFwV1hjitcdvdkSspAWXmayRApR9c wbOKTfA0FDzu6wz/h4MGkt0i8cFT9NwQAgnzph9RFdt7FCWiww+RzVW1D FB/JsAId3bePriH15JSi1LIndezR99X3ByZWQo0rrFeMS5T4EBdZNn+nd Jcq7ROdpcOnc6Oua4NPJkD9CRFcznyoO7MLkeo/ghIYIQYYxzMFJylnnw m8QXglmuGJseI943+Gpvki5CxUkfMOLZawPzcGGfJ+0KqgR0W7ZWf2/gU w==; X-CSE-ConnectionGUID: w4/N4rzeS3iPFAHnd1Istg== X-CSE-MsgGUID: +Lh75nGuRK6MTyehOU+4hQ== X-IronPort-AV: E=McAfee;i="6800,10657,11698"; a="71904462" X-IronPort-AV: E=Sophos;i="6.21,285,1763452800"; d="scan'208";a="71904462" Received: from fmviesa009.fm.intel.com ([10.60.135.149]) by fmvoesa111.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Feb 2026 13:13:37 -0800 X-CSE-ConnectionGUID: PsnzZ1HYSdeHmpeL+SH0KQ== X-CSE-MsgGUID: sWHoGZYHQzqkOljRNqoQpQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,285,1763452800"; d="scan'208";a="211349854" Received: from soc-pf446t5c.clients.intel.com (HELO [10.24.81.126]) ([10.24.81.126]) by fmviesa009-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Feb 2026 13:13:37 -0800 Message-ID: Date: Wed, 11 Feb 2026 13:13:36 -0800 Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 3/3] virt: tdx-guest: Increase Quote buffer size to 128KB To: dan.j.williams@intel.com, Kiryl Shutsemau Cc: Dave Hansen , Rick Edgecombe , x86@kernel.org, linux-kernel@vger.kernel.org, linux-coco@lists.linux.dev References: <20260211001712.1531955-1-sathyanarayanan.kuppuswamy@linux.intel.com> <20260211001712.1531955-4-sathyanarayanan.kuppuswamy@linux.intel.com> <6983882c-2c00-42f4-924b-5fb3619840be@linux.intel.com> <698cef4964e8_8c32100a3@dwillia2-mobl4.notmuch> Content-Language: en-US From: Kuppuswamy Sathyanarayanan In-Reply-To: <698cef4964e8_8c32100a3@dwillia2-mobl4.notmuch> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Dan, On 2/11/2026 1:06 PM, dan.j.williams@intel.com wrote: > Kuppuswamy Sathyanarayanan wrote: >> Hi Kiryl, >> >> Thanks for the review! >> >> On 2/11/2026 3:17 AM, Kiryl Shutsemau wrote: >>> On Tue, Feb 10, 2026 at 04:17:12PM -0800, Kuppuswamy Sathyanarayanan wrote: >>>> Intel platforms are transitioning from traditional SGX-based >>>> attestation toward DICE-based attestation as part of a broader move >>>> toward open and standardized attestation models. DICE enables layered >>>> and extensible attestation, where evidence is accumulated across >>>> multiple boot stages. >>>> >>>> With SGX-based attestation, Quote sizes are typically under 8KB, as the >>>> payload consists primarily of Quote data and a small certificate bundle. >>>> Existing TDX guest code sizes the Quote buffer accordingly. >>>> >>>> DICE-based attestation produces significantly larger Quotes due to the >>>> inclusion of evidence (certificate chains) from multiple boot layers. >>>> The cumulative Quote size can reach approximately 100KB. >>>> >>>> Increase GET_QUOTE_BUF_SIZE to 128KB to ensure sufficient buffer >>>> capacity for DICE-based Quote payloads. >>> >>> It worth noting that it requires guest physically-contiguous memory. >>> >>> Single order-5 allocation is not that bad as long as the driver >>> initialized during the boot. >> >> Good point! We can add following to the commit log: >> >> The Quote buffer requires guest physically-contiguous memory and is >> allocated once during driver initialization at boot time, where an >> order-5 allocation (128KB) is expected to succeed reliably. > > That is good feedback. I would rather not restart the timer on the > linux-next exposure with a rebase to add that. I think in this case it > is sufficient that the commit has a link back to this discussion: > > Link: https://patch.msgid.link/20260211001712.1531955-4-sathyanarayanan.kuppuswamy@linux.intel.com > > However, when the the patch to add the link to the documentation for the > CBOR Web Token schema is ready, do take the opportunity to also add a > patch commenting about the order-5 allocation risk to > GET_QUOTE_BUF_SIZE. Sounds good. Once the CWT documentation is ready, I will send a follow-up patch that includes both the documentation link and the order-5 allocation comment. > > Later, when / if these objects start to get into order-10+ allocations > for PQC etc, a scatter-gather mechanism will need to be considered. -- Sathyanarayanan Kuppuswamy Linux Kernel Developer