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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_NONE,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 9DDACC2B9F8 for ; Tue, 25 May 2021 04:32:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7F6EC6117A for ; Tue, 25 May 2021 04:32:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230408AbhEYEdt (ORCPT ); Tue, 25 May 2021 00:33:49 -0400 Received: from mga09.intel.com ([134.134.136.24]:43726 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230362AbhEYEds (ORCPT ); Tue, 25 May 2021 00:33:48 -0400 IronPort-SDR: +uhbcqOHd7wA9YNhzCmfRdnZYiFM3sQjqy1vK7CBkKLmFXYMJ6T/6XzawRuOMQLMUk065NNp95 QHj+V7NBDXpg== X-IronPort-AV: E=McAfee;i="6200,9189,9994"; a="202117360" X-IronPort-AV: E=Sophos;i="5.82,327,1613462400"; d="scan'208";a="202117360" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 May 2021 21:32:18 -0700 IronPort-SDR: heGkg7XcPm+7AyaDDQ76iObltkvNVrChLI4sxyYol32YGHGm3C7B3v/2pEpRPkFB+n7ZMN5u9r Je8y8N53OmjA== X-IronPort-AV: E=Sophos;i="5.82,327,1613462400"; d="scan'208";a="479108855" Received: from caknoll-mobl.amr.corp.intel.com (HELO [10.209.100.8]) ([10.209.100.8]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 May 2021 21:32:17 -0700 Subject: Re: [RFC v2-fix-v2 2/2] x86/tdx: Ignore WBINVD instruction for TDX guest To: Andi Kleen , Dan Williams Cc: "Kuppuswamy, Sathyanarayanan" , Peter Zijlstra , Andy Lutomirski , 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> <125f8362-b1e3-d304-f943-3fc2f07b5d79@linux.intel.com> From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <125f8362-b1e3-d304-f943-3fc2f07b5d79@linux.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/24/21 7:13 PM, Andi Kleen wrote: > I don't see any point of all of this. We really just want to be the same > as KVM. Not get into the business of patching a bazillion sub systems > that cannot be used in TDX anyways. Andi, there's a fundamental difference between KVM the hypervisor and a TDX guest: KVM the hypervisor runs unknown guests, and lots of them. TD guest support as a whole has to handle one thing: running *one* Linux kernel. Further, the guest support shares a source tree with that kernel. TD guest support doesn't have to run random binaries for which there is no source. All of the source is *RIGHT* *THERE*. The only reason TD guest support would have to fall back to KVM's dirty tricks is a desire to treat the rest of the kernel like a black box. KVM frankly has no other choice. TD guest support has all the choices in the world.