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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 4C010C4CECC for ; Mon, 27 Apr 2020 20:14:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 38B972072D for ; Mon, 27 Apr 2020 20:14:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726797AbgD0UOz (ORCPT ); Mon, 27 Apr 2020 16:14:55 -0400 Received: from mga03.intel.com ([134.134.136.65]:40490 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726285AbgD0UOy (ORCPT ); Mon, 27 Apr 2020 16:14:54 -0400 IronPort-SDR: 2tI4Oi6oIwWQxfcHsi4pG7mnOpH0z17RXnFf0APwjr6EOY/u4yEGozpMerBr9dXHUA6KT1gdhW z357f45VHSXw== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Apr 2020 13:14:54 -0700 IronPort-SDR: oSH1QzudxMhvrNKYYa85wCPYgn+CzdEisFQatM2S+MaevgrPdVt+tmmUWR2NSoLtOYQv8SqrGt 31V5QV9sFD6Q== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,325,1583222400"; d="scan'208";a="404431741" Received: from romley-ivt3.sc.intel.com ([172.25.110.60]) by orsmga004.jf.intel.com with ESMTP; 27 Apr 2020 13:14:53 -0700 Date: Mon, 27 Apr 2020 13:13:57 -0700 From: Fenghua Yu To: Thomas Gleixner Cc: Ingo Molnar , Borislav Petkov , H Peter Anvin , David Woodhouse , Lu Baolu , Dave Hansen , Tony Luck , Ashok Raj , Jacob Jun Pan , Dave Jiang , Sohil Mehta , Ravi V Shankar , linux-kernel , x86 , iommu@lists.linux-foundation.org Subject: Re: [PATCH 1/7] docs: x86: Add a documentation for ENQCMD Message-ID: <20200427201357.GB242333@romley-ivt3.sc.intel.com> References: <1585596788-193989-1-git-send-email-fenghua.yu@intel.com> <1585596788-193989-2-git-send-email-fenghua.yu@intel.com> <87368qtsqz.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87368qtsqz.fsf@nanos.tec.linutronix.de> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Apr 26, 2020 at 01:02:12PM +0200, Thomas Gleixner wrote: > Fenghua Yu writes: > > s/Add a documentation/Add documentation/ > > > From: Ashok Raj > > > > ENQCMD and Data Streaming Accelerator (DSA) and all of their associated > > features are a complicated stack with lots of interconnected pieces. > > This documentation provides a big picture overview for all of the > > features. > > > > Signed-off-by: Ashok Raj > > Co-developed-by: Fenghua Yu > > Signed-off-by: Fenghua Yu > > Reviewed-by: Tony Luck > > --- > > Documentation/x86/enqcmd.rst | 185 +++++++++++++++++++++++++++++++++++ > > How is that hooked up into the Documentation index? > > Documentation/x86/enqcmd.rst: WARNING: document isn't included in any toctree > > > +++ b/Documentation/x86/enqcmd.rst > > @@ -0,0 +1,185 @@ > > +.. SPDX-License-Identifier: GPL-2.0 > > + > > +Improved Device Interaction Overview > > So the document is about ENQCMD, right? Can you please make that in some > way consistently named? > > > + > > +== Background == > > This lacks any docbook formatting.... The resulting HTML looks like ... > > > + > > +Shared Virtual Addressing (SVA) allows the processor and device to use the > > +same virtual addresses avoiding the need for software to translate virtual > > +addresses to physical addresses. ENQCMD is a new instruction on Intel > > +platforms that allows user applications to directly notify hardware of new > > +work, much like doorbells are used in some hardware, but carries a payload > > +that carries the PASID and some additional device specific commands > > +along with it. > > Sorry that's not background information, that's an agglomeration of > words. > > Can you please explain properly what's the background of SVA, how it > differs from regular device addressing and what kind of requirements it > has? > > ENQCMD is not related to background. It's part of the new technology. > > > +== Address Space Tagging == > > + > > +A new MSR (MSR_IA32_PASID) allows an application address space to be > > +associated with what the PCIe spec calls a Process Address Space ID > > +(PASID). This PASID tag is carried along with all requests between > > +applications and devices and allows devices to interact with the process > > +address space. > > Sigh. The important part here is not the MSR. The important part is to > explain what PASID is and where it comes from. Documentation has similar > rules as changelogs: > > 1) Provide context > > 2) Explain requirements > > 3) Explain implementation > > The pile you provided is completely backwards and unstructured. Ok. Will address all of the comments. Thanks. -Fenghua