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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 2F90DC56201 for ; Sun, 8 Nov 2020 23:08:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B989F206DC for ; Sun, 8 Nov 2020 23:08:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="NiBdShb0" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728979AbgKHXIl (ORCPT ); Sun, 8 Nov 2020 18:08:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33104 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727929AbgKHXIl (ORCPT ); Sun, 8 Nov 2020 18:08:41 -0500 X-Greylist: delayed 3505 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Sun, 08 Nov 2020 15:08:41 PST Received: from twosheds.infradead.org (twosheds.infradead.org [IPv6:2001:8b0:10b:1:21d:7dff:fe04:dbe2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 24754C0613CF; Sun, 8 Nov 2020 15:08:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=twosheds.20170209; h=Content-Transfer-Encoding: Content-Type:MIME-Version:Cc:To:From:Subject:Date:References:In-Reply-To: Message-ID:Sender:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=ip8hF5BftOjZIayundc04w+NG5HSfhZUwkO7oX7/MuE=; b=NiBdShb0quc3A87cncLeElMkU Cri9O/nbA3Q+cNPO5g/LWL4pRN8LVSIPCprSE7pkDC1/SD+RCusucXgeaGh083P9AzPmUcSurgctN 65DwvYtYuTDYLCGpw0sFErehScpOJwI5U+OjZs5j2fKo66NvnHgjrLxy+16yxG8HAbhbpHOsW3g3Q DH1Xx6+f/SMU1g87foW1UhUlpzDmkWdfoeqoQwmj9FvQVJEqZJtl/dikNVCxzNLdSAg3rmyg22Djm EvYat3/TMQuvYHlgDzjAPBV9dYu8A0rQ/uebwa1ueCrRheDuAUIf4sOmDgctB+CIy55cyaOOZieDl bs9trAlLA==; Received: from localhost ([127.0.0.1] helo=twosheds.infradead.org) by twosheds.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kbssT-00CBlH-SM; Sun, 08 Nov 2020 22:09:38 +0000 Received: from 2001:8b0:10b:1:b16b:5d8a:941b:e15c (SquirrelMail authenticated user dwmw2) by twosheds.infradead.org with HTTP; Sun, 8 Nov 2020 22:09:38 -0000 Message-ID: <59034a932606e25c0b260540fff0b6dc.squirrel@twosheds.infradead.org> In-Reply-To: <87k0uvk0oc.fsf@nanos.tec.linutronix.de> References: <20201030224534.GN2620339@nvidia.com> <20201102132158.GA3352700@nvidia.com> <20201103124351.GM2620339@nvidia.com> <20201104124017.GW2620339@nvidia.com> <20201104135415.GX2620339@nvidia.com> <20201106131415.GT2620339@nvidia.com> <87k0uvk0oc.fsf@nanos.tec.linutronix.de> Date: Sun, 8 Nov 2020 22:09:38 -0000 Subject: Re: [PATCH v4 06/17] PCI: add SIOV and IMS capability detection From: "David Woodhouse" To: "Thomas Gleixner" Cc: "Jason Gunthorpe" , "Tian\, Kevin" , "Jiang\, Dave" , "Bjorn Helgaas" , "vkoul\@kernel.org" , "Dey\, Megha" , "maz\@kernel.org" , "bhelgaas\@google.com" , "alex.williamson\@redhat.com" , "Pan\, Jacob jun" , "Raj\, Ashok" , "Liu\, Yi L" , "Lu\, Baolu" , "Kumar\, Sanjay K" , "Luck\, Tony" , "jing.lin\@intel.com" , "Williams\, Dan J" , "kwankhede\@nvidia.com" , "eric.auger\@redhat.com" , "parav\@mellanox.com" , "rafael\@kernel.org" , "netanelg\@mellanox.com" , "shahafs\@mellanox.com" , "yan.y.zhao\@linux.intel.com" , "pbonzini\@redhat.com" , "Ortiz\, Samuel" , "Hossain\, Mona" , "dmaengine\@vger.kernel.org" , "linux-kernel\@vger.kernel.org" , "linux-pci\@vger.kernel.org" , "kvm\@vger.kernel.org" User-Agent: SquirrelMail/1.4.23 [SVN]-1.fc30.20190710 MIME-Version: 1.0 Content-Type: text/plain;charset=utf-8 Content-Transfer-Encoding: 8bit X-Priority: 3 (Normal) Importance: Normal X-SRS-Rewrite: SMTP reverse-path rewritten from by twosheds.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org > On Fri, Nov 06 2020 at 09:14, Jason Gunthorpe wrote: >> On Fri, Nov 06, 2020 at 09:48:34AM +0000, Tian, Kevin wrote: >> For instance you could put a "disable IMS" flag in the ACPI tables, in >> the config space of the emuulated root port, or any other areas that >> clearly belong to the platform. >> >> The OS logic would be >> - If no IMS information found then use IMS (Bare metal) >> - If the IMS disable flag is found then >> - If (future) hypercall available and the OS knows how to use it >> then use IMS >> - If no hypercall found, or no OS knowledge, fail IMS > > That does not work because an older hypervisor would not have that > disable flag and the guest kernel would assume to be on bare metal (if > no other indicators are there). In the absence of a forward-thinking design from Intel perhaps we could use the existence of an IOMMU with interrupt remapping and not caching mode as the indication that it's bare metal? -- dwmw2