From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id C63C3C87FCB for ; Fri, 1 Aug 2025 14:22:52 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 687556B0088; Fri, 1 Aug 2025 10:22:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 65F276B0092; Fri, 1 Aug 2025 10:22:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5748F6B0098; Fri, 1 Aug 2025 10:22:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 499F66B0088 for ; Fri, 1 Aug 2025 10:22:52 -0400 (EDT) Received: from smtpin05.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id E12F2140210 for ; Fri, 1 Aug 2025 14:22:51 +0000 (UTC) X-FDA: 83728404942.05.B632731 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.12]) by imf25.hostedemail.com (Postfix) with ESMTP id CBE7FA000B for ; Fri, 1 Aug 2025 14:22:48 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b="F74/a2Go"; spf=pass (imf25.hostedemail.com: domain of dave.hansen@intel.com designates 192.198.163.12 as permitted sender) smtp.mailfrom=dave.hansen@intel.com; dmarc=pass (policy=none) header.from=intel.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1754058169; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=PrKvqOTTeDmmlK2wPlGTzcr6zzrYd71zNNQRYkXXFHg=; b=PPwos2YtEmigNZtRqoHkGx5MwpmCLpmGCIionQjnIqb0m4SK51hphMII+oDMerJJTj7VYp fly/xCw5R2PlQW1QLrrwCTb831bmeAeKfI87nY3XmpWwr8lm1ezMdRiTjSNxqxBilbsVwq qUz7PtXTFTBaAjy2/TQ020CO27rnxRk= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1754058169; a=rsa-sha256; cv=none; b=Lv2J1h8W9W5zrsb3pCuA6iN/Sfd/SZTLgGjnzP7HV4cA662s7v+qk5E1AWZ2VMTZh7zOMm ScLnT/YGuWwpnyoqF37mZglxt5XWYy0jey9hlzcIuKrzTVpPm8Op+5OmDAZsjHtULlh9Zf u0h0Vay/T2hrJJyB2uU2JxXqtAMCmrY= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b="F74/a2Go"; spf=pass (imf25.hostedemail.com: domain of dave.hansen@intel.com designates 192.198.163.12 as permitted sender) smtp.mailfrom=dave.hansen@intel.com; dmarc=pass (policy=none) header.from=intel.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1754058168; x=1785594168; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=R8gdx/rlUEZmt+RtRpsjUtcCGgtiXFr2+h4yEpIqmpA=; b=F74/a2GogSaAksiewwbi8/IIHb1gf3zoVIYbhVG5YyYQYEXQ0BdklRRG hsmYf9x78m1hQpJVOHmj8tgsqO3XX6OpXPWxFitkIDfu2ChvjoaoTNaWf MVxhGvOeqtV5tBc3++GQqaEl0OCcUPwarM3DCkA2Nc1e/Dt4VLgtu3OPs eLE2RQvLjrYiJ4VAbQYU16eWQO8NP1G+NCkVgGhaKLqlU02pSN6KKllhH IZorr8G7N2iY+Qp3uYaQW0kc+iH5ufG7t1VDkQxxUJ33QKS16+mFjwOdn rv7CceIy8Y/vkH05seT4t+D1RBHUDyhh4HNqrdNl8yFWK2MXSb57t6rPy w==; X-CSE-ConnectionGUID: ZSotWJwlTF+sMwmL3ilEng== X-CSE-MsgGUID: Ob5my1v2Qh6v8VQ/GJr24g== X-IronPort-AV: E=McAfee;i="6800,10657,11508"; a="60223926" X-IronPort-AV: E=Sophos;i="6.17,255,1747724400"; d="scan'208";a="60223926" Received: from fmviesa009.fm.intel.com ([10.60.135.149]) by fmvoesa106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Aug 2025 07:22:47 -0700 X-CSE-ConnectionGUID: 6hznr9LGQhKITDFl+xzaWg== X-CSE-MsgGUID: rkSxHCIaQDaZGP+fdThzoA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.17,255,1747724400"; d="scan'208";a="163949374" Received: from aschofie-mobl2.amr.corp.intel.com (HELO [10.125.109.249]) ([10.125.109.249]) by fmviesa009-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Aug 2025 07:22:45 -0700 Message-ID: Date: Fri, 1 Aug 2025 07:22:44 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCHv9 04/16] x86/cpu: Defer CR pinning setup until core initcall To: Sohil Mehta , Thomas Gleixner , Dave Hansen , Kees Cook Cc: Jonathan Corbet , Ingo Molnar , Pawan Gupta , Daniel Sneddon , Kai Huang , Sandipan Das , Breno Leitao , Rick Edgecombe , Alexei Starovoitov , Hou Tao , Juergen Gross , Vegard Nossum , Eric Biggers , Jason Gunthorpe , "Masami Hiramatsu (Google)" , Andrew Morton , Luis Chamberlain , Yuntao Wang , Rasmus Villemoes , Christophe Leroy , Tejun Heo , Changbin Du , Huang Shijie , Geert Uytterhoeven , Namhyung Kim , Arnaldo Carvalho de Melo , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org, linux-mm@kvack.org, "Kirill A. Shutemov" , "Kirill A. Shutemov" , Andy Lutomirski , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Peter Zijlstra , Ard Biesheuvel , "Paul E. McKenney" , Josh Poimboeuf , Xiongwei Song , Xin Li , "Mike Rapoport (IBM)" , Brijesh Singh , Michael Roth , Tony Luck , Alexey Kardashevskiy , Alexander Shishkin , X86-kernel References: <20250707080317.3791624-1-kirill.shutemov@linux.intel.com> <20250707080317.3791624-5-kirill.shutemov@linux.intel.com> <6075af69-299f-43d2-a3c8-353a2a3b7ee7@intel.com> <98a7a91b-3b46-4407-82a7-5f80443b7e00@intel.com> <6e768f25-3a1c-48b9-bc53-56877a556a83@intel.com> <1c42680f-c962-4a75-998f-031008dd8343@intel.com> 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: <1c42680f-c962-4a75-998f-031008dd8343@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: CBE7FA000B X-Stat-Signature: aw6k3uwxsndoottrd1azf47ets958zmg X-Rspam-User: X-HE-Tag: 1754058168-857173 X-HE-Meta: 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 H8e2n2Oh eYAFYJFjpqUXv0n+32I3wfY5Tog/ayt0UyFTKKMoUEU9raKJRPSjqu/zGK1SJ4us0wksAuO4wEicIYvNMB07pitCuS80IRZZJHidb+0QLBis7Mj6/44+PoqwXxszn2BF/N07VBXeH6liKhKVCAEWqEkMTAINO5M3oNcLm1rUfgeO54cmKKK9wkVJm0TPhvcMHigod049ukUppawPDfS1BKizwKFkAjlSFvdRn+WDhIzfHskOkQ2+2VtPFZ8yCaJAnBgu+DYWMZ/k0q2YF4EzVx0I4mHnxSts12ecV X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/31/25 21:43, Sohil Mehta wrote: ... > Could deferring enforcement lead to a scenario where we end up with > different CR4 values on different CPUs? Maybe I am misinterpreting this > and protecting against in-kernel errors is not a goal. Sure, theoretically. But if that's a concern, it can be checked at the time that enforcement starts: for_each_online_cpu(cpu) { unsigned long cr4 = per_cpu(cpu_tlbstate.cr4, cpu); if ((cr4 & cr4_pinned_mask) == cr4_pinned_bits)) continue; WARN("blah blah"); } Or use smp_call_function() to check each CPU's CR4 directly. Or, the next time that CPU does a TLB flush that toggles X86_CR4_PGE, it'll get the warning from the regular pinning path. So, sure, this does widen the window during boot where a secondary CPU might get a bad CR4 value, and it would make it harder to track down where it happened. We _could_ print a pr_debug() message when the bit gets cleared but not enforce things if anyone is super worried about this. > In general, you want to delay the CR pinning enforcement until > absolutely needed. I am curious about the motivation. I understand we > should avoid doing it at arbitrary points in the boot. But, > arch_cpu_finalize_init() and early_initcall() seem to be decent > mileposts to me. > > Are you anticipating that we would need to move setup_cr_pinning() again > when another user similar to EFI shows up? Yep.