From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.12]) (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 C328837268F for ; Tue, 21 Jul 2026 13:48:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.12 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784641707; cv=none; b=te+TD83lUGoFsskeTpmO+bOvc9pZYwRi3tLlX09HPWm4BjZA57z4CrjJ5zFMQLP9c3DUZbtaaMn0ki3GU+MtIw4c50ceZiP57UeBNE+X0hr9HizrQxSjFlc7cl1KhWC//YiAKOFE4abqyxQ9h93Y0qsB9B7CSbbN/b9dTJyz55U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784641707; c=relaxed/simple; bh=+kTfAZlspn4CjQ5xpb6BJomNVOltPv9WBk47OYSF3yc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=jKNKppgjMLg3ym4MIgFK1+i/XcDK1kSDaMVVktdmcf0szJ2NhjbvriISg8GN8xW+TPUCJECKb6Nz5wrZpMHVe22h7Y3q5jDVcF8p0H5DYWwufkRNydFvpgZ7Qv6RjwDXQMiUtg6Oze3ErYlpQweHrgSYSkiQzXymH3i755yajPA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=m1YJBktZ; arc=none smtp.client-ip=192.198.163.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="m1YJBktZ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1784641706; x=1816177706; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=+kTfAZlspn4CjQ5xpb6BJomNVOltPv9WBk47OYSF3yc=; b=m1YJBktZbZHHtgIPMAHfl67cxkVogd6RchfGcMFX9WcIwlQTW5WiVHgk VRivYfCitUhxIEJfkcBc62cHSimyffmlKA2Iq9Czxy/bN5JeSAYGbIy3V 2YNRonX6bgWjAJz57TktWb0V9bDKSlJtoOZ+o1BHZT//RpUPViH6G+FgM eNepAmZABQTlPGsRpZ7VozZmwMWSvtPIdDYz2hEfLWfT0vwMiscVzLfX4 AS947sqUadR6ru4VBZUlcaSe02qAhWcxWKVAHJnCyYQ7kL774dsU2wmhy 1aCtEpI/yvezzieWUdVN9aRD4+Y1v/mOldBhNH+haXyHqM0nsK1qVud9W Q==; X-CSE-ConnectionGUID: GHvBEwr1T0OU4HBhNAsHkA== X-CSE-MsgGUID: mojR2RIVQqCNLYEfJZyzAg== X-IronPort-AV: E=McAfee;i="6800,10657,11852"; a="89067374" X-IronPort-AV: E=Sophos;i="6.25,176,1779174000"; d="scan'208";a="89067374" Received: from orviesa003.jf.intel.com ([10.64.159.143]) by fmvoesa106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Jul 2026 06:48:25 -0700 X-CSE-ConnectionGUID: DvXOHyCxQEGMceMYGJoLFQ== X-CSE-MsgGUID: FgMncIInS3+r53Mit9LCfA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,176,1779174000"; d="scan'208";a="261326837" Received: from schen9-mobl4.amr.corp.intel.com (HELO [10.125.109.227]) ([10.125.109.227]) by ORVIESA003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Jul 2026 06:48:25 -0700 Message-ID: Date: Tue, 21 Jul 2026 06:48:24 -0700 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 v2 2/2] virt: tdx-guest: Allocate Quote buffer dynamically To: Peter Fang Cc: Dave Hansen , Kiryl Shutsemau , Rick Edgecombe , Kuppuswamy Sathyanarayanan , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org, linux-coco@lists.linux.dev, kvm@vger.kernel.org, Xiaoyao Li , Binbin Wu References: <20260717214349.4075994-1-peter.fang@intel.com> <20260717214349.4075994-3-peter.fang@intel.com> <51059852-9a10-4735-a81d-003b4b1963a6@intel.com> <20260721064907.GG3178326@pedri> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; keydata= xsFNBE6HMP0BEADIMA3XYkQfF3dwHlj58Yjsc4E5y5G67cfbt8dvaUq2fx1lR0K9h1bOI6fC oAiUXvGAOxPDsB/P6UEOISPpLl5IuYsSwAeZGkdQ5g6m1xq7AlDJQZddhr/1DC/nMVa/2BoY 2UnKuZuSBu7lgOE193+7Uks3416N2hTkyKUSNkduyoZ9F5twiBhxPJwPtn/wnch6n5RsoXsb ygOEDxLEsSk/7eyFycjE+btUtAWZtx+HseyaGfqkZK0Z9bT1lsaHecmB203xShwCPT49Blxz VOab8668QpaEOdLGhtvrVYVK7x4skyT3nGWcgDCl5/Vp3TWA4K+IofwvXzX2ON/Mj7aQwf5W iC+3nWC7q0uxKwwsddJ0Nu+dpA/UORQWa1NiAftEoSpk5+nUUi0WE+5DRm0H+TXKBWMGNCFn c6+EKg5zQaa8KqymHcOrSXNPmzJuXvDQ8uj2J8XuzCZfK4uy1+YdIr0yyEMI7mdh4KX50LO1 pmowEqDh7dLShTOif/7UtQYrzYq9cPnjU2ZW4qd5Qz2joSGTG9eCXLz5PRe5SqHxv6ljk8mb ApNuY7bOXO/A7T2j5RwXIlcmssqIjBcxsRRoIbpCwWWGjkYjzYCjgsNFL6rt4OL11OUF37wL QcTl7fbCGv53KfKPdYD5hcbguLKi/aCccJK18ZwNjFhqr4MliQARAQABzUVEYXZpZCBDaHJp c3RvcGhlciBIYW5zZW4gKEludGVsIFdvcmsgQWRkcmVzcykgPGRhdmUuaGFuc2VuQGludGVs LmNvbT7CwXgEEwECACIFAlQ+9J0CGwMGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEGg1 lTBwyZKwLZUP/0dnbhDc229u2u6WtK1s1cSd9WsflGXGagkR6liJ4um3XCfYWDHvIdkHYC1t MNcVHFBwmQkawxsYvgO8kXT3SaFZe4ISfB4K4CL2qp4JO+nJdlFUbZI7cz/Td9z8nHjMcWYF IQuTsWOLs/LBMTs+ANumibtw6UkiGVD3dfHJAOPNApjVr+M0P/lVmTeP8w0uVcd2syiaU5jB aht9CYATn+ytFGWZnBEEQFnqcibIaOrmoBLu2b3fKJEd8Jp7NHDSIdrvrMjYynmc6sZKUqH2 I1qOevaa8jUg7wlLJAWGfIqnu85kkqrVOkbNbk4TPub7VOqA6qG5GCNEIv6ZY7HLYd/vAkVY E8Plzq/NwLAuOWxvGrOl7OPuwVeR4hBDfcrNb990MFPpjGgACzAZyjdmYoMu8j3/MAEW4P0z F5+EYJAOZ+z212y1pchNNauehORXgjrNKsZwxwKpPY9qb84E3O9KYpwfATsqOoQ6tTgr+1BR CCwP712H+E9U5HJ0iibN/CDZFVPL1bRerHziuwuQuvE0qWg0+0SChFe9oq0KAwEkVs6ZDMB2 P16MieEEQ6StQRlvy2YBv80L1TMl3T90Bo1UUn6ARXEpcbFE0/aORH/jEXcRteb+vuik5UGY 5TsyLYdPur3TXm7XDBdmmyQVJjnJKYK9AQxj95KlXLVO38lczsFNBFRjzmoBEACyAxbvUEhd GDGNg0JhDdezyTdN8C9BFsdxyTLnSH31NRiyp1QtuxvcqGZjb2trDVuCbIzRrgMZLVgo3upr MIOx1CXEgmn23Zhh0EpdVHM8IKx9Z7V0r+rrpRWFE8/wQZngKYVi49PGoZj50ZEifEJ5qn/H Nsp2+Y+bTUjDdgWMATg9DiFMyv8fvoqgNsNyrrZTnSgoLzdxr89FGHZCoSoAK8gfgFHuO54B lI8QOfPDG9WDPJ66HCodjTlBEr/Cwq6GruxS5i2Y33YVqxvFvDa1tUtl+iJ2SWKS9kCai2DR 3BwVONJEYSDQaven/EHMlY1q8Vln3lGPsS11vSUK3QcNJjmrgYxH5KsVsf6PNRj9mp8Z1kIG qjRx08+nnyStWC0gZH6NrYyS9rpqH3j+hA2WcI7De51L4Rv9pFwzp161mvtc6eC/GxaiUGuH BNAVP0PY0fqvIC68p3rLIAW3f97uv4ce2RSQ7LbsPsimOeCo/5vgS6YQsj83E+AipPr09Caj 0hloj+hFoqiticNpmsxdWKoOsV0PftcQvBCCYuhKbZV9s5hjt9qn8CE86A5g5KqDf83Fxqm/ vXKgHNFHE5zgXGZnrmaf6resQzbvJHO0Fb0CcIohzrpPaL3YepcLDoCCgElGMGQjdCcSQ+Ci FCRl0Bvyj1YZUql+ZkptgGjikQARAQABwsFfBBgBAgAJBQJUY85qAhsMAAoJEGg1lTBwyZKw l4IQAIKHs/9po4spZDFyfDjunimEhVHqlUt7ggR1Hsl/tkvTSze8pI1P6dGp2XW6AnH1iayn yRcoyT0ZJ+Zmm4xAH1zqKjWplzqdb/dO28qk0bPso8+1oPO8oDhLm1+tY+cOvufXkBTm+whm +AyNTjaCRt6aSMnA/QHVGSJ8grrTJCoACVNhnXg/R0g90g8iV8Q+IBZyDkG0tBThaDdw1B2l asInUTeb9EiVfL/Zjdg5VWiF9LL7iS+9hTeVdR09vThQ/DhVbCNxVk+DtyBHsjOKifrVsYep WpRGBIAu3bK8eXtyvrw1igWTNs2wazJ71+0z2jMzbclKAyRHKU9JdN6Hkkgr2nPb561yjcB8 sIq1pFXKyO+nKy6SZYxOvHxCcjk2fkw6UmPU6/j/nQlj2lfOAgNVKuDLothIxzi8pndB8Jju KktE5HJqUUMXePkAYIxEQ0mMc8Po7tuXdejgPMwgP7x65xtfEqI0RuzbUioFltsp1jUaRwQZ MTsCeQDdjpgHsj+P2ZDeEKCbma4m6Ez/YWs4+zDm1X8uZDkZcfQlD9NldbKDJEXLIjYWo1PH hYepSffIWPyvBMBTW2W5FRjJ4vLRrJSUoEfJuPQ3vW9Y73foyo/qFoURHO48AinGPZ7PC7TF vUaNOTjKedrqHkaOcqB185ahG2had0xnFsDPlx5y In-Reply-To: <20260721064907.GG3178326@pedri> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/20/26 23:49, Peter Fang wrote: ... >> This is all talking about post-quantum-crypto and all that fancy stuff. >> >> Isn't the important part here that the old TDX module ABI had static >> quote sizes and now they're dynamic? Now, the reason it changed is all >> the fancy stuff. >> >> But the ABI changed. Right? > > Ah yes... I should call out that the size of > /sys/kernel/config/tsm/report/$name/outblob will no longer be fixed. > I'll update this. Thanks. No. I mean the TDX Module ABI changed. That's why we need new kernel patches. >> The host may be untrusted, but it's also a critical part of the system. >> Are we sure we want to be completely quiet? >> >> I used to see little dmesg warnings about TCP window shenanigans from >> random systems on the Internet. Maybe that's not how we do things today, >> but if a random dude on the Internet can spew one line to dmesg, is it >> that crazy that a bad VMM be able to spew a warning? > > That makes sense... I actually argued with AI about this but it kept > saying this is kind of like DoSing the guest. But thinking about it > more, tainting the guest is probably the right thing to do... At least > the guest sees a big splat about why attestation is failing. I'll remove > the __GFP_NOWARN. Thanks. This does seem like the kind of high-level TDX policy that we all need to be aligned on and probably document somewhere. The basic question is whether a TDX guest should be quiet or verbose in the face of host malfunction or malfeasance. Kirill and Rick, what do you think?