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=-9.6 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 autolearn=ham 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 7722BC433EF for ; Fri, 10 Sep 2021 07:15:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 443DC611CA for ; Fri, 10 Sep 2021 07:15:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231459AbhIJHQQ (ORCPT ); Fri, 10 Sep 2021 03:16:16 -0400 Received: from terminus.zytor.com ([198.137.202.136]:45759 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231433AbhIJHQO (ORCPT ); Fri, 10 Sep 2021 03:16:14 -0400 Received: from tazenda.hos.anvin.org ([IPv6:2601:646:8600:3c70:7285:c2ff:fefb:fd4]) (authenticated bits=0) by mail.zytor.com (8.16.1/8.15.2) with ESMTPSA id 18A7EVYA350052 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Fri, 10 Sep 2021 00:14:32 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 18A7EVYA350052 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2021083001; t=1631258073; bh=eU0ElfVj1/mQmWtKeUyg1o4QluHw1VPYo4/0678CeKs=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=WIF5D1iEFN+MUrrsHNdEK3BEC2Ojo4cRclKlkyuwPlHygKnt+u9buVEoOgtbm3GjQ cNaVS7iWyMz+hZK8WQnYyRhGucKfaPud1gi1Mz9nOEUv4T+pXpsGV2ZXon+mx6Tgu9 HWDDK5ped4XZaGRL/NEQk1L3Lb+EARIyLDq5qg1+2H8xFRd0h1czi11wAtxpmplMr7 VtSxk6kuhtnxu1qLwxQwy0JbBNfcGvfl4lDqPF+5tlEKssZ2ey1c6JpUd3qCWN5zjZ QkSUiXfYmQp1KhTWXwudKjOcfX8lAlvqCW/UFXF67IdnrjiUqo25XPPaMvDxUV+nBT KGfB4AQkm6Rmw== Subject: Re: [PATCH 17/24] x86/entry: Introduce struct ist_regs To: Lai Jiangshan , Lai Jiangshan , linux-kernel@vger.kernel.org Cc: Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, Joerg Roedel , Youquan Song , Tony Luck , Juergen Gross , "Peter Zijlstra (Intel)" References: <20210831175025.27570-1-jiangshanlai@gmail.com> <20210831175025.27570-18-jiangshanlai@gmail.com> <9fe0e26b-5fb7-4521-a01e-8edd8d5cb74c@zytor.com> <3729bc02-1e4b-d2db-aabb-cb3610d8fd7d@linux.alibaba.com> From: "H. Peter Anvin" Message-ID: Date: Fri, 10 Sep 2021 00:14:26 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <3729bc02-1e4b-d2db-aabb-cb3610d8fd7d@linux.alibaba.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/10/21 12:13 AM, Lai Jiangshan wrote: > > > On 2021/9/10 12:31, H. Peter Anvin wrote: >> Note: the examples in this email all compiled with: >> >> gcc -O2 -mpreferred-stack-boundary=3 -mcmodel=kernel >> >> The disassembly has been slightly simplified. > > Saving results in registers is non-flexible no matter in ASM or hack in > C like this. > > Saving CR3 in ist_regs is not different than saving rax in pt_regs, and > both of > ist_regs and embedded pt_regs can be moved when stack is required to > switch. > > I prefer to my original design. > I agree. I was having some issues following your arguments. -hpa