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X-IronPort-AV: E=McAfee;i="6600,9927,10742"; a="358126953" X-IronPort-AV: E=Sophos;i="6.00,247,1681196400"; d="scan'208";a="358126953" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Jun 2023 09:26:40 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10743"; a="887144847" X-IronPort-AV: E=Sophos;i="6.00,247,1681196400"; d="scan'208";a="887144847" Received: from fashta-mobl.amr.corp.intel.com (HELO [10.255.231.221]) ([10.255.231.221]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Jun 2023 09:26:39 -0700 Message-ID: <6655bcdc-e658-3ba1-ed7a-3fe1eadef48a@intel.com> Date: Fri, 16 Jun 2023 09:26:39 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: [PATCH v11 20/20] Documentation/x86: Add documentation for TDX host support Content-Language: en-US To: Nikolay Borisov , Kai Huang , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: linux-mm@kvack.org, kirill.shutemov@linux.intel.com, tony.luck@intel.com, peterz@infradead.org, tglx@linutronix.de, seanjc@google.com, pbonzini@redhat.com, david@redhat.com, dan.j.williams@intel.com, rafael.j.wysocki@intel.com, ying.huang@intel.com, reinette.chatre@intel.com, len.brown@intel.com, ak@linux.intel.com, isaku.yamahata@intel.com, chao.gao@intel.com, sathyanarayanan.kuppuswamy@linux.intel.com, bagasdotme@gmail.com, sagis@google.com, imammedo@redhat.com References: <34853e0f8f38ec2fda66b0ba480d4df63b8aab43.1685887183.git.kai.huang@intel.com> <14c2a806-05e4-a9f8-e85f-70b2081cd22f@suse.com> From: Dave Hansen In-Reply-To: <14c2a806-05e4-a9f8-e85f-70b2081cd22f@suse.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: C238518001C X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: usa9g9m4d79m3hxg98d9k4tokr554sx6 X-HE-Tag: 1686932801-869687 X-HE-Meta: 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 cJRj7f/W Rmo6AS6fbYbcBK6w5dSdh8IX10ril2VZn5DwPSilxCzbIKvMUldI9DbYYnjtMRUIpqiZiiVj+b7yBEmbqI7TUrh9P9nM4UIfCEb3KpDujJZa2u0toVLNxZf5hHnNbUDX03chosjBnMRmLVJ5MxBjfkAg3JQooLd19B3ZxiGCjObwd6T0= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000005, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 6/16/23 02:02, Nikolay Borisov wrote: >> >> +TDX reports a list of "Convertible Memory Region" (CMR) to tell the > > nit: It might be worth mentioning that those CMRs ultimately come from > the BIOS.  Because it's never mentioned here and in the "Physical Memory > Hotplug" it's directly mentioned that bios shouldn't support hot-removal > of memory. So the bios is a central component in a sense. The BIOS is weird on TDX systems. It's central, sure, but it's also untrusted. The TDX module generally has a kind of "trust but verify" approach to the BIOS. I guess the BIOS is the one poking at the memory controllers and getting the DIMMs fired up. But I _do_ think it's OK to say that CMRs come from the TDX module. The important thing is that they're trusted.