From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.17]) (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 4FCA41946AA for ; Wed, 1 Oct 2025 20:50:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.17 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759351816; cv=none; b=bcF8mkE9PvhFvVD55WQDV6iXcvYszF5xQh0/fLif1tQJMc2N/w7p1NLo9EdgWAlCps/Mc/Ben+gYVSaoZc8byyuktCTISdxn5kF8uF4eaM7WnQRjvpy2MSVTEN/Rkge7XD4cEbYSiPSh93rGkkYvGdUs0FnELp29oZD8ChsAwbg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759351816; c=relaxed/simple; bh=IB8uPb6EUBcGWblRPI+e7U2JqmalxFcJYmMrRUroNbE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=SFd4xkNi7CzCjakSPQnINWb+Tou1cjs8MnoPlkoj+HWY7F00BW/jSVrHCalvNThFIY17PZ8Kz2PKJYtqB1elZmud54sOmr3VzYq2YYVj47zF2+KDROhC+M/n3DxbGnY3WuU1cTYbuSObV1qKBNrEBxK215zJcZJcA7XvurCE2+U= 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=UlJkZC+g; arc=none smtp.client-ip=192.198.163.17 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="UlJkZC+g" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1759351815; x=1790887815; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=IB8uPb6EUBcGWblRPI+e7U2JqmalxFcJYmMrRUroNbE=; b=UlJkZC+gMZBOJMYDC/P+KFqB8n4iFMTlKHCv95/8CkwCwT+xxLUWjDNY +08Gq5FB7zdv1TbOhBSx5gjAuFH+hNiceJjP+aa20xXpfuERt7HHj0t/I HlPEXmEhkAPTqjoZJbQPxxdFOQZGyxX8Zd/oWNSz3mmdgkzxJGCExYASN n/Trq/f2uBAM92SpzaeUPbqktZ9pjF9I+CO9u/brKtolZGICbhodnJze2 oOEY+ShaefE7IFFcf/AU6IHdga+p+Zne5Xqa8FzWJURCz5Tg64yj0S3me qta0dLCakAGu1CPUvLLPj9Mkoo7usd+TF8DqdvoTib2Ho7bnBaNHypwbX g==; X-CSE-ConnectionGUID: F9Cs7N+fTWee25bG1EeoJQ== X-CSE-MsgGUID: 4iuaLDA1TtC/46V//q9J1A== X-IronPort-AV: E=McAfee;i="6800,10657,11569"; a="61548718" X-IronPort-AV: E=Sophos;i="6.18,307,1751266800"; d="scan'208";a="61548718" Received: from orviesa010.jf.intel.com ([10.64.159.150]) by fmvoesa111.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Oct 2025 13:50:14 -0700 X-CSE-ConnectionGUID: PphuQsj6R32nVbv8mRQWjA== X-CSE-MsgGUID: Q6Riu27eRkCBy6UsEdHvtA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.18,307,1751266800"; d="scan'208";a="178166843" Received: from gabaabhi-mobl2.amr.corp.intel.com (HELO [10.125.109.221]) ([10.125.109.221]) by orviesa010-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Oct 2025 13:50:14 -0700 Message-ID: <08338619-6aa1-4905-bdf8-bf1a90857307@intel.com> Date: Wed, 1 Oct 2025 13:50:13 -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 05/21] x86/mm/pat: mirror direct map changes to ASI To: Brendan Jackman , Andy Lutomirski , Lorenzo Stoakes , "Liam R. Howlett" , Suren Baghdasaryan , Michal Hocko , Johannes Weiner , Zi Yan , Axel Rasmussen , Yuanchu Xie , Roman Gushchin Cc: peterz@infradead.org, bp@alien8.de, dave.hansen@linux.intel.com, mingo@redhat.com, tglx@linutronix.de, akpm@linux-foundation.org, david@redhat.com, derkling@google.com, junaids@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, reijiw@google.com, rientjes@google.com, rppt@kernel.org, vbabka@suse.cz, x86@kernel.org, Yosry Ahmed References: <20250924-b4-asi-page-alloc-v1-0-2d861768041f@google.com> <20250924-b4-asi-page-alloc-v1-5-2d861768041f@google.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: <20250924-b4-asi-page-alloc-v1-5-2d861768041f@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/24/25 07:59, Brendan Jackman wrote: > ASI has a separate PGD for the physmap, which needs to be kept in sync > with the unrestricted physmap with respect to permissions. So that leads to another thing... What about vmalloc()? Why doesn't it need to be in the ASI pgd? > +static inline bool is_direct_map(unsigned long vaddr) > +{ > + return within(vaddr, PAGE_OFFSET, > + PAGE_OFFSET + (max_pfn_mapped << PAGE_SHIFT)); > +} > > static int __cpa_process_fault(struct cpa_data *cpa, unsigned long vaddr, > int primary) > @@ -1808,8 +1814,7 @@ static int __cpa_process_fault(struct cpa_data *cpa, unsigned long vaddr, > * one virtual address page and its pfn. TBD: numpages can be set based > * on the initial value and the level returned by lookup_address(). > */ > - if (within(vaddr, PAGE_OFFSET, > - PAGE_OFFSET + (max_pfn_mapped << PAGE_SHIFT))) { > + if (is_direct_map(vaddr)) { > cpa->numpages = 1; > cpa->pfn = __pa(vaddr) >> PAGE_SHIFT; > return 0; > @@ -1981,6 +1986,27 @@ static int cpa_process_alias(struct cpa_data *cpa) > return 0; > } > > +/* > + * Having updated the unrestricted PGD, reflect this change in the ASI > + * restricted address space too. > + */ > +static inline int mirror_asi_direct_map(struct cpa_data *cpa, int primary) > +{ > + struct cpa_data asi_cpa = *cpa; > + > + if (!asi_enabled_static()) > + return 0; > + > + /* Only need to do this for the real unrestricted direct map. */ > + if ((cpa->pgd && cpa->pgd != init_mm.pgd) || !is_direct_map(*cpa->vaddr)) > + return 0; > + VM_WARN_ON_ONCE(!is_direct_map(*cpa->vaddr + (cpa->numpages * PAGE_SIZE))); > + > + asi_cpa.pgd = asi_nonsensitive_pgd; > + asi_cpa.curpage = 0; Please document what functionality this curpage=0 has. It's not clear. > + return __change_page_attr(cpa, primary); > +} But let's say someone is doing something silly like: set_memory_np(addr, size); set_memory_p(addr, size); Won't that end up in here and make the "unrestricted PGD" have _PAGE_PRESENT==1 entries? Also, could we try and make the nomenclature consistent? We've got "unrestricted direct map" and "asi_nonsensitive_pgd" being used (at least). Could the terminology be made more consistent? One subtle thing here is that it's OK to allocate memory here when mirroring changes into 'asi_nonsensitive_pgd'. It's just not OK when flipping sensitivity. That seems worth a comment. > static int __change_page_attr_set_clr(struct cpa_data *cpa, int primary) > { > unsigned long numpages = cpa->numpages; > @@ -2007,6 +2033,8 @@ static int __change_page_attr_set_clr(struct cpa_data *cpa, int primary) > if (!debug_pagealloc_enabled()) > spin_lock(&cpa_lock); > ret = __change_page_attr(cpa, primary); > + if (!ret) > + ret = mirror_asi_direct_map(cpa, primary); > if (!debug_pagealloc_enabled()) > spin_unlock(&cpa_lock); > if (ret) > Is cpa->pgd ever have any values other than NULL or init_mm->pgd? I didn't see anything in a quick grep.