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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E90AFE7717F for ; Tue, 17 Dec 2024 15:06:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=gH2PyObVwOTb7IJJA/kCLtpfRftXTti8G2/J9onHbvw=; b=MbyRdEYzeymhzu7aR3Sv/vk4md PO3zDKc2xgRQm4qtDS0Cky/3dtpR1hfagHV4+TiCdonSSgDVth9eebrYrJMKfOLD4BIxplZruR7pN C9sHXUgVAx6dNlFoi8Pcd59fkUbwZS0o0Lk9kza+RYQBphGIyBj8fdxOCblxKyzBMPskByX8CSBrS +Yq9YDJrQFLrRDsCw3MvZr1vo4Gv4DAW7QGtoje5LfQnXfy4axrpwBCGa7NzjOLddYAvsGpK5vrVG o3jeZQskW5USPhTRXjKQbBtq4qOyttJ9WfSel9VovYyxHtKzjICdcVUyIbNX7t8oSoQWVsQA935qA lzWZUrNg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tNZ9G-0000000DsoN-19Se; Tue, 17 Dec 2024 15:06:10 +0000 Received: from mgamail.intel.com ([198.175.65.20]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tNZ9D-0000000Dsmm-3I9c for kexec@lists.infradead.org; Tue, 17 Dec 2024 15:06:08 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1734447968; x=1765983968; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=VYgUBCCBapVjhIc533Rzulgo4zhAc4lsjV5YP7+N/ME=; b=a+6C0Kk2Nn3vlw4yC1/h1ohaNaFaS+QN8cCcd+b1CRLMFnTthscy3M8u u29566XKpBnplOa48xEtSzDtYAWPl0qe4XJ+xsbyUpN1HI6DWNywasnBQ 9wb5WHW1AILffw8qUhgmj9wzWdqQkDK4+ZLQwrXnRx5BS1t5j7OcVl+qP FFG9B2pGrqjcNzTaOAtKXExTPl7lvRroEKEF+72bKjpXyP7KBzFG52fK6 Srd5+BRfvh8AabglYX83A+WHUmf1SEEhTX/OtrSwhG4wt5Tk3hhDB7Yx+ zjHvmTL3XqBpKu/R84f9IX9j2cIAGHQlDJzqWvdUo92Ny0xNYi6xQDtuY g==; X-CSE-ConnectionGUID: TTdtNVfrR2GKesucN+DA+w== X-CSE-MsgGUID: fmW+DZHPSdGfKIMedtgexA== X-IronPort-AV: E=McAfee;i="6700,10204,11288"; a="34606911" X-IronPort-AV: E=Sophos;i="6.12,242,1728975600"; d="scan'208";a="34606911" Received: from fmviesa002.fm.intel.com ([10.60.135.142]) by orvoesa112.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Dec 2024 07:06:07 -0800 X-CSE-ConnectionGUID: 0HCoLGcPS36/QgdTdVVypA== X-CSE-MsgGUID: 9Y8BEF/kR+Sqb8PeC7alNw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,224,1728975600"; d="scan'208";a="120810844" Received: from ssimmeri-mobl2.amr.corp.intel.com (HELO [10.124.220.135]) ([10.124.220.135]) by fmviesa002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Dec 2024 07:06:05 -0800 Message-ID: Date: Tue, 17 Dec 2024 07:06:03 -0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [EXTERNAL] [PATCH 1/9] x86/kexec: Disable global pages before writing to control page To: David Woodhouse , "Kirill A. Shutemov" Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Eric Biederman , Sourabh Jain , Hari Bathini , Michael Ellerman , Thomas Zimmermann , Andrew Morton , Baoquan He , Yuntao Wang , David Kaplan , Tao Liu , Kai Huang , Ard Biesheuvel , Josh Poimboeuf , Breno Leitao , Wei Yang , Rong Xu , =?UTF-8?Q?Thomas_Wei=C3=9Fschuh?= , linux-kernel@vger.kernel.org, kexec@lists.infradead.org, Simon Horman , Dave Young , Peter Zijlstra , bsz@amazon.de, nathan@kernel.org References: <20241216233704.3208607-1-dwmw2@infradead.org> <20241216233704.3208607-2-dwmw2@infradead.org> <28a98c27-7307-4698-9182-35e0d2cf12ad@intel.com> <7593b839a8c7d3122e08660ca2e957d834665005.camel@infradead.org> 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: <7593b839a8c7d3122e08660ca2e957d834665005.camel@infradead.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241217_070607_878175_F8E62ACF X-CRM114-Status: GOOD ( 10.26 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On 12/17/24 06:56, David Woodhouse wrote: >> Anyway, I think we can leave the belt-and-suspenders programming in this >> case. A comment wouldn't hurt I guess. > I'm a little lost. In this case I don't see belt-and-suspenders > programming. We're not loading CR3 after clearing CR4.PGE just to be > paranoid about making really really sure the TLB is flushed. > > We're loading CR3 because we're switching from the kernel's page tables > to the new identity mapping set up for the relocate_kernel environment. Yes, agreed, that's another reason the CR3 write must stay. I hadn't even considered that part yet honestly.