From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.18]) (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 09C0313A258 for ; Sun, 19 Jul 2026 15:52:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784476375; cv=none; b=EXfQWlyQ5OtcBLeSx7AM5yCs2L7NmEFVG2Es9qzyVsldrO7X4xwherkjnk/H1FoFqvoHI88HUMRKroyaAQKqQAhqNQcfMqRdVbxPDwM/u3qR/3r5BBr5IV97scQFlqcAAgCIG0JHtZpfk+ngohB6zul9YjRV6vvAIagDTyjFdtw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784476375; c=relaxed/simple; bh=f9Xf9yE+AP5RB0pRjzanI/nakit4uG8rfuYkCZMogiU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=eJkxHGAVHdrojvTJaooDFXB8NxJOgxF85+EYjXQr7F9ZQ8LJKRrZkbcXJAJGbjOcgUHE3DftgQb9TUQRmcJJwKzb2Cm2a5oSKKvhyWH0Wsn815LG3n89JULyv++ldANUmn7e+Mt44lDUJD1NNODdPQ34h9RpWEeC0NyJJBVsCQk= 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=R//XkGC6; arc=none smtp.client-ip=198.175.65.18 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="R//XkGC6" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1784476373; x=1816012373; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=f9Xf9yE+AP5RB0pRjzanI/nakit4uG8rfuYkCZMogiU=; b=R//XkGC6Xm0bfh8lgR0qkD5RckjIjbZugkmWTxM3Wfw/A7jiKIHfEW7t j/u5wFANieSMFPFK12FhVecrrqLf6HunVPvqQmSb9qsYnJQp0zAOmoqdZ S/KsBU/tlZCGAmoMKjxAgCoZk6+FYh1VwBWlSaMZWiYBJEPx5O1w8nwRg oZq/LlFQblNrq+eB1r1ZEZOlptf1MQFxtXycrmLuiLSWVYgUmYPHKh/k/ 7Mxoyrkx93Ksm0fBX9cMTFn245/fgNOOh5haNmuH9j6C/WsMjWPBA4vyG fN5e1H1JhM3uhYNABN2hdySdAoQ/vBTR0TG1Ik7LzcYUtBeWsTlxzr9ql w==; X-CSE-ConnectionGUID: QGnmb3Y4TY6j5w5oGfuzaQ== X-CSE-MsgGUID: WWO3FgnZSa+FCva0zp2VkA== X-IronPort-AV: E=McAfee;i="6800,10657,11851"; a="85170939" X-IronPort-AV: E=Sophos;i="6.25,172,1779174000"; d="scan'208";a="85170939" Received: from orviesa008.jf.intel.com ([10.64.159.148]) by orvoesa110.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Jul 2026 08:52:53 -0700 X-CSE-ConnectionGUID: qkbyj3gRSMC0eTYHJRB+kg== X-CSE-MsgGUID: 8HwyW0X1TU+pS1HWjHgOag== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,172,1779174000"; d="scan'208";a="256671213" Received: from aduenasd-mobl5.amr.corp.intel.com (HELO [10.125.109.145]) ([10.125.109.145]) by orviesa008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Jul 2026 08:52:52 -0700 Message-ID: Date: Sun, 19 Jul 2026 08:52:51 -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: [PATCH] x86/microcode/intel: Panic on partial microcode update To: "Maciej W. Rozycki" Cc: "Chang S. Bae" , linux-kernel@vger.kernel.org, x86@kernel.org, tglx@kernel.org, Ingo Molnar , bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com References: <20260630191350.3837-1-chang.seok.bae@intel.com> <4f2a4841-0a73-4f44-aec8-890734660a9c@intel.com> Content-Language: en-US From: Dave Hansen 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 7/18/26 15:54, Maciej W. Rozycki wrote: > On Tue, 30 Jun 2026, Dave Hansen wrote: >> Thinking about this a bit more: I don't think we should panic. It's >> perfectly fine to spew a nice scary warning. But we really should >> continue unless we really *know* that something has gone so horribly >> wrong that it's dangerous to continue. > > Is there no risk for silent data corruption such as in storage after a > broken ucode update? Is there no risk for silent data corruption such as in storage after a kernel panic? Is there no risk for silent data corruption such as in storage after a use after free or a stray write? Or any other bog standard kernel bug? We don't aim for "zero risk", IMNHO. We can't. >> I mean, the ucode update guys themselves could definitely have reset the >> system if it needed to. They also know when it is dangerous to keep the >> CPU running. They obviously don't think that this partial update thing >> is *THAT* dangerous or they wouldn't have even let the CPU keep >> churning. Right? > > Umm, what the reasonable alternative would be for the RTL designer, a CPU > shutdown? Then you'd have no good way to figure out what really happened. There are actually a huge number of things that can happen to a CPU that result in a reset or other conditions that are really hard to debug. Thankfully, most of them get debugged out of the system before end users ever get them. But folks who work with early silicon frequently get to experience the joy of having no good way to figure out what really happened. Those "early" folks have lots of other tools at their disposal. But, believe me, the RTL designers and ucode writers are not shy about killing the system if data corruption is at all likely. Chang, have you seen anything at all in the specs or from our Intel colleagues that makes you think that it's _dangerous_ to keep running rather than killing the system as soon as possible?