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 3AC43C19F28 for ; Wed, 3 Aug 2022 14:23:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238518AbiHCOXU (ORCPT ); Wed, 3 Aug 2022 10:23:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44218 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238815AbiHCOWx (ORCPT ); Wed, 3 Aug 2022 10:22:53 -0400 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B30BF2A244; Wed, 3 Aug 2022 07:22:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1659536571; x=1691072571; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=ARwyAl2EszMC/rUU5o5wSvHaFBqvGsQKMB4jjBXC5Dw=; b=NVwjBQNvq8ZpNqCxZyyESGSiGG5FRgnZDqFldz6PGKRC/4vW3PlxoUx1 xSEmR/dmjRBQTUNrr0QpXY2AIO9+H6DepC20FRU4KtWATHCmmleqjd3TG OPUTyt0FwRUiuB950TDpcbfeb3VN8JZr0FME6g1NLoOb8YHdGVDMcdS02 XZkedO+TAjIqc6+mHrNjnlHPxxBeW2m21XJztYLRntne83ShOcQ4fDF0e RxJMBpE/jr4kfi0O8hpTM2yvUAHpHvcxFwEmrMQ3Q8l69yZIC/33YXn0v 7aUzZgFb9VA9wm9uOjfAxG76LX4cEQUSmXMrCxb/TkhES2CqMGHN0+/J1 g==; X-IronPort-AV: E=McAfee;i="6400,9594,10428"; a="290900314" X-IronPort-AV: E=Sophos;i="5.93,214,1654585200"; d="scan'208";a="290900314" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Aug 2022 07:22:51 -0700 X-IronPort-AV: E=Sophos;i="5.93,214,1654585200"; d="scan'208";a="631166445" Received: from buichris-mobl.amr.corp.intel.com (HELO [10.209.124.150]) ([10.209.124.150]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Aug 2022 07:22:50 -0700 Message-ID: <675ac8a7-be1c-9e9e-9530-bd1488c99dc9@intel.com> Date: Wed, 3 Aug 2022 07:22:51 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH v5 12/22] x86/virt/tdx: Convert all memory regions in memblock to TDX memory Content-Language: en-US To: Kai Huang , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: seanjc@google.com, pbonzini@redhat.com, len.brown@intel.com, tony.luck@intel.com, rafael.j.wysocki@intel.com, reinette.chatre@intel.com, dan.j.williams@intel.com, peterz@infradead.org, ak@linux.intel.com, kirill.shutemov@linux.intel.com, sathyanarayanan.kuppuswamy@linux.intel.com, isaku.yamahata@intel.com References: <8288396be7fedd10521a28531e138579594d757a.1655894131.git.kai.huang@intel.com> <20d63398-928f-0c6f-47ec-8e225c049ad8@intel.com> <76d7604ff21b26252733165478d5c54035d84d98.camel@intel.com> <880f3991-09e5-2f96-d5ba-213cff05c458@intel.com> From: Dave Hansen In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/2/22 18:30, Kai Huang wrote: > On Fri, 2022-07-08 at 11:34 +1200, Kai Huang wrote: >>> Why not just entirely remove the lower 1MB from the memblock structure >>> on TDX systems?  Do something equivalent to adding this on the kernel >>> command line: >>> >>>   memmap=1M$0x0 >> I will explore this option.  Thanks! > Hi Dave, > > After investigating and testing, we cannot simply remove first 1MB from e820 > table which is similar to what 'memmap=1M$0x0' does, as the kernel needs low > memory as trampoline to bring up all APs. OK, so don't remove it, but reserve it so that the trampoline code can use it.