From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.15]) (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 6F9223128A5; Wed, 24 Sep 2025 15:22:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.15 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758727378; cv=none; b=T+MTFLHxJqeBszwhy0dDQN3PPXYpRNVkY0Kzfl9lS7oqQV2HlTwTsn1zKTACBMUzOj5glmg/XE+TBBYmc7XN1lXOGUZozsYaNtfF/2Cpo7ikDEnID+xsDhwttYOsCjNxMXqx7ryZzAnj0lkJUJaWCgKw9mrdKY/pBIkG2I1v1d8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758727378; c=relaxed/simple; bh=9FSqIIwXDqd1Nl4Sgu22L2OgaVxxMMfrGlCM2cOd8j4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=EUoOsyUCyVysJdg+1aoFK25oC8VgVtiwdsKxu0ouXLput6rhC5CAHzt79D9cZjX2JYer1QBs3NyyHUf8kGaJ0DuxpI7XR4Z+saVfzOSrMkZJZDfEI0LZS81hFLc11E5uGyVORFfWI1y8LHDyx1FgoXJJ+qDJvw7QBTUezyw69/I= 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=XONWgUBA; arc=none smtp.client-ip=192.198.163.15 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="XONWgUBA" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1758727376; x=1790263376; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=9FSqIIwXDqd1Nl4Sgu22L2OgaVxxMMfrGlCM2cOd8j4=; b=XONWgUBANdyLGhA+jQTzQGVryTRIZm1St+YVyS7Emje0siZ9oPXKtWkN MmioFyOX/V+IBpTM3k8QIkKub4ScXJHP6KiPT8ZZiMY8jzPzrw71EK0cj n24IvQ2q3ZGy9nm9B1YJt2EQNW529g+4Vz+BwgPE7lZKVb8mnO1jYNd46 lAQYCzhQtTpVIkEK/VIgoIcHBk67zmidcu1uaSwNqvzWujp7SBAAbj8tw HsNU4hSMipEHX1xoDXw3cZHtvhDWQZUrcC8Txt9j84DrXxGI1b2C+ai6V z6XyirHbmYQkVX+tFZDOGH8UQyo+9KH+kJXG9DaCl8yJL5rm+1aveVXOF Q==; X-CSE-ConnectionGUID: ans+8oe+RJa3qkTg+EdD/w== X-CSE-MsgGUID: oe60dS9IQE2AavudeHEZhA== X-IronPort-AV: E=McAfee;i="6800,10657,11563"; a="61139520" X-IronPort-AV: E=Sophos;i="6.18,290,1751266800"; d="scan'208";a="61139520" Received: from orviesa010.jf.intel.com ([10.64.159.150]) by fmvoesa109.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Sep 2025 08:22:55 -0700 X-CSE-ConnectionGUID: vnpI5k51TQyVScNEzj38sg== X-CSE-MsgGUID: HgPSRiiyTniQo9YXckPuCw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.18,290,1751266800"; d="scan'208";a="176357091" Received: from tfalcon-desk.amr.corp.intel.com (HELO [10.125.108.203]) ([10.125.108.203]) by orviesa010-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Sep 2025 08:22:55 -0700 Message-ID: <40419dea-666e-4a8d-97a7-fa571d7122f4@intel.com> Date: Wed, 24 Sep 2025 08:22:54 -0700 Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC 0/5] parker: PARtitioned KERnel To: Fam Zheng , linux-kernel@vger.kernel.org Cc: Lukasz Luba , linyongting@bytedance.com, songmuchun@bytedance.com, satish.kumar@bytedance.com, Borislav Petkov , Thomas Gleixner , yuanzhu@bytedance.com, Ingo Molnar , Daniel Lezcano , Zhang Rui , fam@euphon.net, "H. Peter Anvin" , x86@kernel.org, liangma@bytedance.com, Dave Hansen , "Rafael J. Wysocki" , guojinhui.liam@bytedance.com, linux-pm@vger.kernel.org, Thom Hughes References: <20250923153146.365015-1-fam.zheng@bytedance.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: <20250923153146.365015-1-fam.zheng@bytedance.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/23/25 08:31, Fam Zheng wrote: > In terms of fault isolation or security, all kernel instances share > the same domain, as there is no supervising mechanism. A kernel bug > in any partition can cause problems for the whole physical machine. > This is a tradeoff for low-overhead / low-complexity, but hope in > the future we can take advantage of some hardware mechanism to > introduce some isolation. I just don't think this is approach is viable. The buck needs to stop _somewhere_. You can't just have a bunch of different kernels, with nothing in charge of the system as a whole. Just think of bus locks. They affect the whole system. What if one kernel turns off split lock detection? Or has a different rate limit than the others? What if one kernel is a big fan of WBINVD? How about when they use resctrl to partition an L3 cache? How about microcode updates? I'd just guess that there are a few hundred problems like that. Maybe more. I'm not saying this won't be useful for a handful of folks in a tightly controlled environment. But I just don't think it has a place in mainline where it needs to work for everyone.