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 314C643847F; Wed, 22 Jul 2026 20:20:42 +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=1784751644; cv=none; b=lcFYzEmrWCQmxvFD16pH/+qamKOADL3Tx/J/QpGFJkRrweJXxa8n/LBnbHGU0n+q/WoT4eVIJJBiO22uBtdmR88eigYr7yzscjvzg6FbXF9GzliZpTqU5ZDHvZP2JU1aZUjH7M+3pmo83jhPe7C5WYPlzlHZJhTxihe7WtBcOMQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784751644; c=relaxed/simple; bh=JGaQKmk/1f26nF/+nvxjfYdWz6Jdt3Ok7POmfjc1hRA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=JwDZN3wUkqGtkcF3Aja9HjPLrmqLgHiYpzr5GLYUiUaFyAWzPLaUIrnR5AeMkTKRkp9X87F1BJkhIlHpg/025N8UOR/KTxA0S2aSCZwr5EtPstmcXOgbMEq00FwEoLKaCvhAzuAEfLIrLbPKk9KiJQFb+jbXETGogmA3b+fRu68= 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=oFDWBzxB; 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="oFDWBzxB" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1784751642; x=1816287642; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=JGaQKmk/1f26nF/+nvxjfYdWz6Jdt3Ok7POmfjc1hRA=; b=oFDWBzxBphjzJyV24BhuWeMGraB8A129Kv28bLlqBKjLgD1nauounry9 qRnCCFp+xjGLeFt5O6qYXQfo8MqLmF4r7DHmYU7NOczTuUMOM9KRpDGtk KRREfzdJFDgni1VoxJa0HxDh2Ho6Fh7uqEbKyfntoeYLrTvcQW2Ku/CR1 jyBpuTqYol1vLIVLem80p+j2ZBIlf+CjmX5C7yDMP2Z0sQOGyG8VHBtmQ Y+uaG2RSjLMpNjUgoAlwrH10eqoN6iRCYRyuhYYUxQrfZeeOlN6BJiVuh EmyK6RWxwzZQYfX7xyKdDY7d65xv0ZUMXwoYsNl+DcdhIu/w0KwDciVMp Q==; X-CSE-ConnectionGUID: B2sAxFEDSHO1dBhhlBMR6w== X-CSE-MsgGUID: kB20sNmhQdmf70UILVTV4g== X-IronPort-AV: E=McAfee;i="6800,10657,11854"; a="85488973" X-IronPort-AV: E=Sophos;i="6.25,179,1779174000"; d="scan'208";a="85488973" Received: from orviesa001.jf.intel.com ([10.64.159.141]) by orvoesa110.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jul 2026 13:20:41 -0700 X-CSE-ConnectionGUID: R4FecRX6TXioPL2/MbQm4Q== X-CSE-MsgGUID: Hfdmu0XVToqbSJhXxxcGdg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,179,1779174000"; d="scan'208";a="296397967" Received: from sghuge-mobl2.amr.corp.intel.com (HELO [10.125.110.58]) ([10.125.110.58]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jul 2026 13:20:40 -0700 Message-ID: <33c774f6-2750-4831-8eee-e43dc471da32@intel.com> Date: Wed, 22 Jul 2026 13:20:39 -0700 Precedence: bulk X-Mailing-List: linux-mips@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC v2 13/20] x86: mm: carve out the generic compile-time folded pgtable case in effective_prot() To: Yeoreum Yun Cc: Russell King , Huacai Chen , WANG Xuerui , Thomas Bogendoerfer , Catalin Marinas , Will Deacon , Arnd Bergmann , Andrew Morton , Kairui Song , Qi Zheng , Shakeel Butt , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Johannes Weiner , David Hildenbrand , Michal Hocko , Lorenzo Stoakes , Tianrui Zhao , Bibo Mao , Anup Patel , Atish Patra , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jonas Bonn , Stefan Kristiansson , Stafford Horne , linux-kernel@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-openrisc@vger.kernel.org References: <20260722-dummy_ptxp3-v2-0-d9e4bad31e0a@arm.com> <20260722-dummy_ptxp3-v2-13-d9e4bad31e0a@arm.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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/22/26 10:37, Yeoreum Yun wrote: >> On 7/22/26 08:30, Yeoreum Yun wrote: >>> struct pg_state { >>> struct ptdump_state ptdump; >>> + int first_level; >>> int level; >>> pgprotval_t current_prot; >>> pgprotval_t effective_prot; >> There is zero reason on x86 to hold this value in a data structure. It >> is 100% determined at boot time or earlier. Pre-5-level-paging it's a >> compile-time constant. >> >> On x86, it never varies per-mm. > However, mm_pXd_folded() requires to mm for other architecture like > s390. might save the mm instead of first_level and calls the > ptdump_pt_level_first() with static inline version would make the > constant comparison. So it requires to save *mm* structure in here. I'm having a really hard time parsing that. I think you're trying to say that the effective_prot_p*() functions need to know the first level but they don't (today) need the mm_struct. If they don't get the (calculated) first_level passed in, they need the mm_struct instead. I think you're arguing 'pg_state' needs a ->first_level or a ->mm. Having a pg_state->mm doesn't seem bad to me at all. But, it's also a little bit silly. It would not be rocket science to pass an mm_struct down to the effective_prot_p*() functions. It makes a whole lot of sense to me for a page table walking function to need metadata from the mm_struct to walk correctly.