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 728AEC77B7A for ; Fri, 2 Jun 2023 15:33:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236705AbjFBPdV (ORCPT ); Fri, 2 Jun 2023 11:33:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46902 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236648AbjFBPdT (ORCPT ); Fri, 2 Jun 2023 11:33:19 -0400 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 71FFDE40; Fri, 2 Jun 2023 08:33:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1685719994; x=1717255994; h=message-id:date:mime-version:subject:to:references:from: in-reply-to:content-transfer-encoding; bh=FJbFB7X8TTc27c3o4L4N59l7VLIbURcwFaTm2eNStOg=; b=fG3Rhksd/Bs8vQ+BIY6Qzjj6cgHwK9KmkOPdUNFO9r1/MPIQSGOnwBEC vw5P9hH7as7sHadxQ2ouMhNfv+X53VHdBpRP2K5IUr7z+TVR5lCSsd7Zm rc3ZbXPnae2xtv/mblJJyMIIvA9+QHjOsZrSCkJgGmaJT8cR0CLW22zZi rYCa+S/grJtdEV+9Xl0OIKlgtj/M3o3thtKLjSao2Lop/9pfPU72OAnCq EWXKerPfy4H2bGLLfBYaMq0Q8jmseaoSUuj3dtiGIWWWH6FS1Bxjheha5 CRJ3Z3GdqyRybRUHksYefnJyHWwfCohia37V92nVod8giVAB3+JC67T20 w==; X-IronPort-AV: E=McAfee;i="6600,9927,10729"; a="358326819" X-IronPort-AV: E=Sophos;i="6.00,213,1681196400"; d="scan'208";a="358326819" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Jun 2023 08:33:13 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10729"; a="740864184" X-IronPort-AV: E=Sophos;i="6.00,213,1681196400"; d="scan'208";a="740864184" Received: from pingshi-mobl.amr.corp.intel.com (HELO [10.251.23.169]) ([10.251.23.169]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Jun 2023 08:33:13 -0700 Message-ID: <442441b3-803e-0c1f-ff1b-5a49ecc2e423@intel.com> Date: Fri, 2 Jun 2023 08:33:13 -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] x86/hyperv: add noop functions to x86_init mpparse functions Content-Language: en-US To: Saurabh Sengar , kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, mikelley@microsoft.com, linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, hpa@zytor.com References: <1685709712-13752-1-git-send-email-ssengar@linux.microsoft.com> From: Dave Hansen In-Reply-To: <1685709712-13752-1-git-send-email-ssengar@linux.microsoft.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org On 6/2/23 05:41, Saurabh Sengar wrote: > In !ACPI system, there is no way to disable CONFIG_X86_MPPARSE. > When CONFIG_X86_MPPARSE is enabled for VTL2, the kernel will > scan low memory looking for MP tables. Don't allow this, because > low memory is controlled by VTL0 and may contain actual valid > tables for VTL0, which can confuse the VTL2 kernel. Do you folks have a writeup of this VTL* setup anywhere? I'm struggling to grasp why VTL0 and VTL2 share the same address space and why they would get confused by each other's data structures. $ grep -r VTL[02] Documentation/ $ Either way, this is way better than the #ifdefs. But the changelog is kinda just gibberish to me.