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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 173A3EB64DB for ; Fri, 16 Jun 2023 16:26:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244879AbjFPQ0q (ORCPT ); Fri, 16 Jun 2023 12:26:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51154 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232001AbjFPQ0m (ORCPT ); Fri, 16 Jun 2023 12:26:42 -0400 Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CF4451A3; Fri, 16 Jun 2023 09:26:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1686932800; x=1718468800; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=kJI27vN2p91Fu6uIkekhD7QZJBwp/dx6T6isHe7/eOM=; b=XMSlJd5QBu6M8J+FeL2kkQjl5dCOLpD676ujDbSJSY4+MSSRzfacXEXz 1qvGhgNvQFCo1RtTO6NnnOKfTMThQMw2MEaZiNq6WPkdeV6U0+2T2Vw6m XnWIODbmXNl42DWkIUHSCMSXgCKxby19cKi1jlJyU10Ur1LawQRYVT05g SseA4X+sXRoum2qFBItc5tufvxYKgJqQvVdnMEZ6vQJRXkRaGSDJJEOfS fXyWWNDAQjyw77szgmphwHZIQBv4EX06jUH5kqLsuG3mKx5i31OVsbJBd jtXeWTWo2vnQhtbh0rVNHdXAFmU7WlBcns5a2HoXRAkl7giskeqgSKZEo w==; X-IronPort-AV: E=McAfee;i="6600,9927,10742"; a="358126950" X-IronPort-AV: E=Sophos;i="6.00,247,1681196400"; d="scan'208";a="358126950" 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.