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 C621FC48BF6 for ; Thu, 7 Mar 2024 15:29:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 476466B01AA; Thu, 7 Mar 2024 10:29:41 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 431EA6B01AB; Thu, 7 Mar 2024 10:29:41 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2EDF86B01AE; Thu, 7 Mar 2024 10:29:41 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 203996B01AA for ; Thu, 7 Mar 2024 10:29:41 -0500 (EST) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id D6788C07EC for ; Thu, 7 Mar 2024 15:29:40 +0000 (UTC) X-FDA: 81870627720.12.2C1C381 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.7]) by imf14.hostedemail.com (Postfix) with ESMTP id B2A0C10000B for ; Thu, 7 Mar 2024 15:29:37 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=jWSBiDb7; spf=pass (imf14.hostedemail.com: domain of dave.hansen@intel.com designates 192.198.163.7 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=1709825378; 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=K0Q3OrVMekfPoYp8FgqfLxSLllocKS3/pff0Kr0+T0w=; b=hQ7sz6t+AmcpcOw2XUnaSbZpooAsuTRZWatwO32u0Op3YyVxdUI3m9DSNoGx2bscusCP61 6oOlSSJxo4yLO/pfUYgUz19iQE07MrIvRSLa02fWT/zyHoDvyzkatOyt3KeINi2PlCxjKG vCShQTDpixmAizD5Le/cdbWNLvVZK1M= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=jWSBiDb7; spf=pass (imf14.hostedemail.com: domain of dave.hansen@intel.com designates 192.198.163.7 as permitted sender) smtp.mailfrom=dave.hansen@intel.com; dmarc=pass (policy=none) header.from=intel.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1709825378; a=rsa-sha256; cv=none; b=3oXfF62q/3Wsob1DXwQ5RE0jRUGWlA27tGQosFXVbBXkYeHc1i5D+OS+5Qic82wCK4aR/k w2lsiiirdQUaMcVHWmWeWoFduDdmIFbvSq2P+SjD4VoB06j87U70ymI3EI6xhSy0xtZ6jb XMxfWjgywu32YP9YRgREHzy88DDRVf4= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1709825378; x=1741361378; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=n/4ugK00duaaQA2HMYCNpKkhT0FB0S+XDjkwT64974E=; b=jWSBiDb7FC7GtpaWFFBOFfpotgmLGnZL+Gw4h1t93TL4UHyIfdZ8Va5j 2q5uLTtH7Ax5YAPjRdsFf94wK6fbX64FZ837A5erVI4nBWh9PZZr68AZe ctWBGjTpYOCoCdBt6qmu+q0rTDdcHtMKvtjSswVsGOM0IdSqw1Egsxmkz qJDFiqGjnySTvrlsj+d15myHgKzwfPYcmVAYt8r+22DfYJEC8XLxASU82 0IxHhvLDNm1RogRMmClZtjIth7iLS/ok1k80HvB5r0Iim1tlUImn56qW8 OPKmu+NwJPYMwmbS2aScu9QXbjQTpghEJwnUXFNJEd1G87ofN1bDJqxmk g==; X-IronPort-AV: E=McAfee;i="6600,9927,11006"; a="29944270" X-IronPort-AV: E=Sophos;i="6.07,211,1708416000"; d="scan'208";a="29944270" Received: from fmviesa005.fm.intel.com ([10.60.135.145]) by fmvoesa101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Mar 2024 07:29:36 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.07,211,1708416000"; d="scan'208";a="14636463" Received: from yuqiangu-mobl.amr.corp.intel.com (HELO [10.209.57.176]) ([10.209.57.176]) by fmviesa005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Mar 2024 07:29:35 -0800 Message-ID: <83b019e2-1b84-491a-b0b9-beb02e45d80c@intel.com> Date: Thu, 7 Mar 2024 07:29:34 -0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 2/3] x86/mm: make sure LAM is up-to-date during context switching Content-Language: en-US To: Yosry Ahmed , Andrew Morton Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Peter Zijlstra , Andy Lutomirski , "Kirill A. Shutemov" , x86@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20240307133916.3782068-1-yosryahmed@google.com> <20240307133916.3782068-3-yosryahmed@google.com> 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: <20240307133916.3782068-3-yosryahmed@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: B2A0C10000B X-Rspam-User: X-Stat-Signature: i9k1dj3hqbrgxmm6p5sk6git7xdasc6j X-Rspamd-Server: rspam01 X-HE-Tag: 1709825377-382680 X-HE-Meta: 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 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 3/7/24 05:39, Yosry Ahmed wrote: > - /* > - * Read the tlb_gen to check whether a flush is needed. > - * If the TLB is up to date, just use it. > - * The barrier synchronizes with the tlb_gen increment in > - * the TLB shootdown code. > - */ > - smp_mb(); > - next_tlb_gen = atomic64_read(&next->context.tlb_gen); > - if (this_cpu_read(cpu_tlbstate.ctxs[prev_asid].tlb_gen) == > - next_tlb_gen) > + if (!need_flush && !need_lam_update) > return; Instead of all this new complexity, why not just inc_mm_tlb_gen() at the site where LAM is enabled? That should signal to any CPU thread that its TLB is out of date and it needs to do a full CR3 reload. Also, have you been able to actually catch this scenario in practice? Considering how fun this code path is, a little effort at an actual reproduction would be really appreciated.