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 5CC1F4E9C11 for ; Mon, 21 Sep 2026 21:32:05 +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=1790026327; cv=none; b=N/lWPGMvSu0+31v6bvJjWBeClVdEDoFaXUgr8X1XSrhGDhPPXCuOHcWqut38cXzuRs17P3Iiwcmd+/VCh+M+1OZrGMZ/Rwc8aABduEn4tHNVgW49ern32veK1iPdysoaWJcv7Ud5wAHOf0iJDb2fjsFd3vx7Ob2a8OuzFx6gDYw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790026327; c=relaxed/simple; bh=7KlAqBunIYpl+bLfnC/xvtTfHiXy+cJyRjwAdnwNotM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=aluED8wL7ZrpCHniFwXL09bPhdWTB5/0EDqpJtsp5X0XnpLdiNgOK8xmVsIC9PE47mqp3jdg5AlzwlddLP/GoS5MCpN52d3WOWI2AiAUt3eOW9fNBpXVqhmjngkiU57o/kIRUVnJc6zPeWHRiKvbgG0UIANuYlYdUjPPHeoGvAg= 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=PQPPBsAY; 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="PQPPBsAY" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1790026325; x=1821562325; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=7KlAqBunIYpl+bLfnC/xvtTfHiXy+cJyRjwAdnwNotM=; b=PQPPBsAYUCl2SgOs/HzxHwUNaTMliGveqHUP7d5bxxjc3nkLM3n3PUPx HpAC1VFFDi04S12ZXJyqdiQq2d3vquo1RaxmejuhkJMozmGStc8UF6c1I LkmB1626zYWtP7L+qGdRhtLCpQWCSI17TGonUwm4vOAUJGuOHc9lsoFB0 DHPy6Xyac8/vyLnuzR6ft5M0ZmM9ngKFUr+sLssh2F3UuX/RP1p7zDWgj 1DLvbW6snQZxBTN44/4H+jsNLo2dMW5SA8xejGPscjE0PcMorHEyek0h9 k5iO9TzZciiLPYaN17assNThK+NxfqcDW0Sv7ul42cS2LYm2Hi1+0hcxS g==; X-CSE-ConnectionGUID: YlqK2xQiQr68riCLK6O/iQ== X-CSE-MsgGUID: a8ihfQclTuSayd2T5ifLtA== X-IronPort-AV: E=McAfee;i="6800,10657,11912"; a="94409665" X-IronPort-AV: E=Sophos;i="6.27,115,1787036400"; d="scan'208";a="94409665" Received: from fmviesa011.fm.intel.com ([10.60.135.151]) by fmvoesa106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Sep 2026 14:32:04 -0700 X-CSE-ConnectionGUID: sHbJVljeRmSmAiM+2iaWLg== X-CSE-MsgGUID: jDZX/iemSF2zP9xrYaXV4A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,115,1787036400"; d="scan'208";a="3919183" Received: from jjgreens-desk24.amr.corp.intel.com (HELO [10.125.109.249]) ([10.125.109.249]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Sep 2026 14:32:04 -0700 Message-ID: Date: Mon, 21 Sep 2026 14:32:04 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: x86 CPUID mutable return values To: ludloff@gmail.com, Borislav Petkov , "Ahmed S. Darwish" Cc: Dave Hansen , Ingo Molnar , Thomas Gleixner , Andrew Cooper , "H. Peter Anvin" , Sean Christopherson , David Woodhouse , Peter Zijlstra , Sohil Mehta , John Ogness , x86@kernel.org, x86-cpuid@lists.linux.dev, LKML References: 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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/21/26 11:36, Christian Ludloff wrote: > Q for Intel: is MSR FEATURE_CONFIG 0x13C bit 1 expected > to affect CPUID 1.ECX.25 and 7.0.ECX.9 and 19.EBX.0/2, or > just just a subset of them? Also, what about PCLMUL? Are you looking to document architecture or implementation here? I poked around on a few pieces of hardware I have within reach and all of them have the MSR FEATURE_CONFIG lock bit set and the disable bit clear. # rdmsr -a 0x13C 1 1 1 1 ... In practice, I suspect the AESNI CPUID bits are immutable. FEATURE_CONFIG's definitions also looks model specific in the spots I see it in the SDM. They're also not identical, interestingly enough. Honestly, FEATURE_CONFIG looks more like something that should have been in the BIOS writers' guide rather than the SDM.