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 X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B2A01C2B9F7 for ; Tue, 25 May 2021 00:36:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 85ADC6100C for ; Tue, 25 May 2021 00:36:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229894AbhEYAh6 (ORCPT ); Mon, 24 May 2021 20:37:58 -0400 Received: from mga12.intel.com ([192.55.52.136]:45301 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229539AbhEYAh5 (ORCPT ); Mon, 24 May 2021 20:37:57 -0400 IronPort-SDR: 7YlEPWpkftMZy2rzp3KBrccBNSX+LDLc5oEUQJBQXGlI/gFI9vmOHNPwbJdkjTHKE6WYzc/wga lBWqNqBdnfSA== X-IronPort-AV: E=McAfee;i="6200,9189,9994"; a="181702956" X-IronPort-AV: E=Sophos;i="5.82,327,1613462400"; d="scan'208";a="181702956" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 May 2021 17:36:23 -0700 IronPort-SDR: PNiE8R7tlZZxl6b4LbKo4BLWsWIzK93sQ+05/lDy6TClUiBMGpG5c5+bmpK0ukdbJ2HOkupc6Z uEzwQ2eLmDEQ== X-IronPort-AV: E=Sophos;i="5.82,327,1613462400"; d="scan'208";a="546281419" Received: from akleen-mobl1.amr.corp.intel.com (HELO [10.212.195.214]) ([10.212.195.214]) by fmsmga001-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 May 2021 17:36:22 -0700 Subject: Re: [RFC v2-fix-v2 2/2] x86/tdx: Ignore WBINVD instruction for TDX guest To: Dan Williams , Kuppuswamy Sathyanarayanan Cc: Peter Zijlstra , Andy Lutomirski , Dave Hansen , Tony Luck , Kirill Shutemov , Kuppuswamy Sathyanarayanan , Raj Ashok , Sean Christopherson , Linux Kernel Mailing List References: <37ad50ca-f568-4c62-56e2-9e9b1f34084c@linux.intel.com> <20210524233211.802033-1-sathyanarayanan.kuppuswamy@linux.intel.com> <20210524233211.802033-2-sathyanarayanan.kuppuswamy@linux.intel.com> From: Andi Kleen Message-ID: Date: Mon, 24 May 2021 17:36:21 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.10.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org that. > I thought we discussed that there are other considerations for wbinvd > besides DMA? In any event this paragraph is actively misleading > because it disregards ACPI and Persistent Memory secure-erase whose > usages of wbinvd have nothing to do with DMA. In this case they would be broken in KVM too. > I would much prefer a > patch to shutdown all the known wbinvd users as a precursor to this > patch rather than assuming it's ok to simply ignore it. You have > mentioned that TDX does not need to use those paths, but rather than > assume they can't be used why not do the audit to explicitly disable > them? Otherwise this statement seems to imply that the audit has not > been done. We're not assuming it. We know it because KVM does it since forever. All we want to do is do the same as KVM. -Andi