From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.13]) (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 59A5512C7E1 for ; Fri, 17 May 2024 15:21:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.13 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715959300; cv=none; b=D5kQxZ7o2l5JF1ErlCFP9joo9p8xlQgUyhR5n0FAJEPCWC90UoyiPl3jxVDa3/FD7OAg4ttyhyd09JVaeg7OAZf6hKlDLm0NvV3hN0d8aBYno/X+ixdLEuIahqFQBvg4XqyeCbeLLb3cIWMUiyzHX/fHKKwZ3tm0CpjFl6kYPqI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715959300; c=relaxed/simple; bh=jpNsC9cI9iGi7aedbr9RL6SWorewOwQj+OYp2jQWsx8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ncfec8aomNoWlBh8N14Z7WXCFtf1kC70y8CGzYlflWL+F6SEYrVVd0vZWdatMBKE7JdZrFwv42yRQwKNsAC5X5ICxJiZRcScHPTaHo0Npu0wRE151VLBlJIe/4vEScYD1/ZQxdSqTGKZSScF2tT8c/9fSicrz7xN2Sm9ZzPY6Yg= 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=cYPrEfsx; arc=none smtp.client-ip=198.175.65.13 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="cYPrEfsx" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1715959299; x=1747495299; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=jpNsC9cI9iGi7aedbr9RL6SWorewOwQj+OYp2jQWsx8=; b=cYPrEfsxPp/Ovf1mb6cABpic0qFnlv6lyrnBtrO81cuJfQqXTZvULHRu 5an1cnfxWNXTGmaKwqOFhg9sbTqq50cf5f2hxBKdZEvjp4M+BJAdMXKOm etYO/2iafAQ9pcv162d5Rpny4aJRXlo7G7vISm9SQIZK1WdROmT950o7k Zmq8wYuR50MYaVqcC52Y+xe1/D8x2U4zR4lOiLtDmATBwqas2fQIekaNs 1dhf2UJAGk7ROOAblNbHOYajUM5WKhSqOnYgAFlGRqzh5WKa5DN2gbEBB xG9swVG8zqZS37UIsQ0QzoWFoKcH46f5nnot1glSjZsoaxxLXLn13a13U w==; X-CSE-ConnectionGUID: 2IjGz8bORNS1bQe5/sXxbQ== X-CSE-MsgGUID: 8vX9ZdlhREyjU/u2X227mw== X-IronPort-AV: E=McAfee;i="6600,9927,11075"; a="23280076" X-IronPort-AV: E=Sophos;i="6.08,168,1712646000"; d="scan'208";a="23280076" Received: from orviesa002.jf.intel.com ([10.64.159.142]) by orvoesa105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 May 2024 08:21:39 -0700 X-CSE-ConnectionGUID: yIfU3bf3Q8agb0Pm4A51zg== X-CSE-MsgGUID: 10hV1spdSGC4s6JDTrAs2g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.08,168,1712646000"; d="scan'208";a="62655258" Received: from kinlongk-mobl1.amr.corp.intel.com (HELO [10.125.108.204]) ([10.125.108.204]) by orviesa002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 May 2024 08:21:38 -0700 Message-ID: <395850c4-f8a3-46ed-9b0c-b1f47386610c@intel.com> Date: Fri, 17 May 2024 08:21:37 -0700 Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 01/20] x86/tdx: Introduce tdvmcall_trampoline() To: "Kirill A. Shutemov" , Sean Christopherson , Paolo Bonzini , Dave Hansen , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Josh Poimboeuf , Peter Zijlstra Cc: linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org References: <20240517141938.4177174-1-kirill.shutemov@linux.intel.com> <20240517141938.4177174-2-kirill.shutemov@linux.intel.com> Content-Language: en-US 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: <20240517141938.4177174-2-kirill.shutemov@linux.intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/17/24 07:19, Kirill A. Shutemov wrote: > TDCALL calls are centralized into a few megawrappers that take the > struct tdx_module_args as input. Most of the call sites only use a few > arguments, but they have to zero out unused fields in the structure to > avoid data leaks to the VMM. This leads to the compiler generating > inefficient code: dozens of instructions per call site to clear unused > fields of the structure. I agree that this is what the silly compiler does in practice. But my first preference for fixing it would just be an out-of-line memset() or a pretty bare REP;MOV. In other words, I think this as the foundational justification for the rest of the series leaves a little to be desired.