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=-14.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1,USER_IN_DEF_DKIM_WL 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 AE9A4C433B4 for ; Fri, 9 Apr 2021 12:23:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8AE2760241 for ; Fri, 9 Apr 2021 12:23:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232985AbhDIMXk (ORCPT ); Fri, 9 Apr 2021 08:23:40 -0400 Received: from linux.microsoft.com ([13.77.154.182]:42432 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232763AbhDIMXf (ORCPT ); Fri, 9 Apr 2021 08:23:35 -0400 Received: from [192.168.86.30] (c-73-38-52-84.hsd1.vt.comcast.net [73.38.52.84]) by linux.microsoft.com (Postfix) with ESMTPSA id E677C20B5680; Fri, 9 Apr 2021 05:23:20 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com E677C20B5680 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1617971002; bh=g1IkxfC02BI2BaL8HcBt5TCTlI/DmrIpd9NIeiz+BX8=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=fDj98FQ0o8C9gtrF5zNWuas2cJ8KOF0kYOBZ9RmYT9qJ8Jo4iRsYJXO8L3kX5B6iK 3LB/y/+2He4rNKz2eYoVDAsWb2ovypwCeabvrYsiDOyGf1Cs0x9sCbyU3qqjLLNOcj qRHsOdSZjrj+OAonLaLjzVJvyKqvYo12nV0IyJF0= Subject: Re: [PATCH 1/7] hyperv: Detect Nested virtualization support for SVM To: Sean Christopherson Cc: Vitaly Kuznetsov , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "K. Y. Srinivasan" , x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, Lan Tianyu , Michael Kelley , Paolo Bonzini , Wanpeng Li , Jim Mattson , Joerg Roedel , Wei Liu , Stephen Hemminger , Haiyang Zhang References: <87lf9tavci.fsf@vitty.brq.redhat.com> From: Vineeth Pillai Message-ID: Date: Fri, 9 Apr 2021 08:23:19 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 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 On 4/8/21 11:24 AM, Sean Christopherson wrote: > > Technically, you can use normal memory accesses, so long as software guarantees > the VMCS isn't resident in the VMCS cache and knows the field offsets for the > underlying CPU. The lack of an architecturally defined layout is the biggest > issue, e.g. tacking on dirty bits through a PV ABI would be trivial. > >> Yes, you are right. I was referring to the fact that we cant use normal >> memory accesses, but is a bit mis-worded. > If you slot in "architectural" it will read nicely, i.e. "VMCB is already an > architectural datastructure in memory". Yes, this makes sense. Thanks for the suggestion, will reword as you suggested. Thanks, Vineeth