From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.12]) (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 A2E011272A2 for ; Tue, 5 Mar 2024 15:21:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.12 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709652102; cv=none; b=rtbd+4JLMIUbdH6gvJgM+x5TBS/A6LEc+vd69D3XqnJ0HAkjfJhTwMJwTQD64T/IJhJ98sj1trLjRkWOf8O9QJrt1xpuhdDX4vqSOZQ0zfZwctCcsRzc9jO6EE1sBYCa3gB87aAZW7pAvRlpbUI75YuBagwnhK7MxBq7WXfgPeI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709652102; c=relaxed/simple; bh=mGjg/oYqkXuL6hLwkDEhYikAg/+ZpH2yGc9lgFzKdcA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=W+ST5tc/P0T2Zy/xjYFBt2tziEx56h/EaJldRKpLTtVNvabVh6LtYYFqyGU24fTqqkKz1f4wcaVb+j3iDiAQvUcgeYX4XYT3wTn6RKazpRNWvO2/d9Jrigam1iouInDB8I8DtkXVm4JZhFZuMNgQhXVoPLRo6O8CMzPNRzGCx60= 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=OmfrLhIK; arc=none smtp.client-ip=192.198.163.12 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="OmfrLhIK" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1709652100; x=1741188100; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=mGjg/oYqkXuL6hLwkDEhYikAg/+ZpH2yGc9lgFzKdcA=; b=OmfrLhIKwtCKupYcxJMOjQIYBGBeLoAgiz7neuoQXcBMmx4+i5oT3kls EBOexzwqIh96t2d/dyZDXWJ1NudRklLqnzop/ZLbVes1OXASPkqC/M1vX lZlMKZcMDasJrxty5Q3NXUTwZMkPRj/3t+CW52O8/Y1g8F8R4nRvicbXi P4pjgJnmWBAkiqJ7PFxpTg78LaAt0Rqp02esVrhvflEGxp/pZ51vDTaDb j1wkg+lfTlDdKmktUA2g1bx/z/hRXI/Yreuy0jf/lYy5sBSf/HIqi1542 MbH9rE7tEAIqC+4wQDqIFRMYTLTGRFN1QCGuE6ywm4Bcf4I+MGwFD/MIX g==; X-IronPort-AV: E=McAfee;i="6600,9927,11003"; a="7979551" X-IronPort-AV: E=Sophos;i="6.06,205,1705392000"; d="scan'208";a="7979551" Received: from orviesa005.jf.intel.com ([10.64.159.145]) by fmvoesa106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Mar 2024 07:21:39 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.06,205,1705392000"; d="scan'208";a="14100520" Received: from mecastro-mobl1.amr.corp.intel.com (HELO [10.212.136.86]) ([10.212.136.86]) by orviesa005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Mar 2024 07:21:39 -0800 Message-ID: <74d900cf-ab90-49ea-ba55-380d7df59526@intel.com> Date: Tue, 5 Mar 2024 07:21:38 -0800 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 v2] x86: disable non-instrumented version of copy_mc when KMSAN is enabled Content-Language: en-US To: Tetsuo Handa , LKML , the arch/x86 maintainers Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" References: <3b7dbd88-0861-4638-b2d2-911c97a4cadf@I-love.SAKURA.ne.jp> 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: <3b7dbd88-0861-4638-b2d2-911c97a4cadf@I-love.SAKURA.ne.jp> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/1/24 14:52, Tetsuo Handa wrote: > unsigned long __must_check copy_mc_to_kernel(void *dst, const void *src, unsigned len) > { > - if (copy_mc_fragile_enabled) > + if (!IS_ENABLED(CONFIG_KMSAN) && copy_mc_fragile_enabled) > return copy_mc_fragile(dst, src, len); > - if (static_cpu_has(X86_FEATURE_ERMS)) > + if (!IS_ENABLED(CONFIG_KMSAN) && static_cpu_has(X86_FEATURE_ERMS)) > return copy_mc_enhanced_fast_string(dst, src, len); > memcpy(dst, src, len); > return 0; > @@ -74,14 +74,14 @@ unsigned long __must_check copy_mc_to_user(void __user *dst, const void *src, un > { > unsigned long ret; > > - if (copy_mc_fragile_enabled) { > + if (!IS_ENABLED(CONFIG_KMSAN) && copy_mc_fragile_enabled) { > __uaccess_begin(); > ret = copy_mc_fragile((__force void *)dst, src, len); > __uaccess_end(); > return ret; > } > > - if (static_cpu_has(X86_FEATURE_ERMS)) { > + if (!IS_ENABLED(CONFIG_KMSAN) && static_cpu_has(X86_FEATURE_ERMS)) { > __uaccess_begin(); > ret = copy_mc_enhanced_fast_string((__force void *)dst, src, len); > __uaccess_end(); Where does the false positive _come_ from? Can we fix copy_mc_fragile() and copy_mc_enhanced_fast_string() instead of just not using them? The three enable_copy_mc_fragile() are presumably doing so for a reason. What is this patch's impact on _those_? Third, instead of sprinkling IS_ENABLED(CONFIG_KMSAN) checks in random spots, can we do this in a central spot?