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=-3.8 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 42E98C433E0 for ; Fri, 17 Jul 2020 14:42:15 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1010222B4D for ; Fri, 17 Jul 2020 14:42:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=citrix.com header.i=@citrix.com header.b="ZtScZ9RC" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1010222B4D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=citrix.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jwRYi-0000XK-VZ; Fri, 17 Jul 2020 14:41:56 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jwRYh-0000XF-NB for xen-devel@lists.xenproject.org; Fri, 17 Jul 2020 14:41:55 +0000 X-Inumbo-ID: a84ff2f2-c83b-11ea-961d-12813bfff9fa Received: from esa5.hc3370-68.iphmx.com (unknown [216.71.155.168]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id a84ff2f2-c83b-11ea-961d-12813bfff9fa; Fri, 17 Jul 2020 14:41:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=citrix.com; s=securemail; t=1594996914; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=aqrREHJIYejtlp3+BeU9+k7NlCM456Us6iYhRhqf5kg=; b=ZtScZ9RCXCXEkWOy2alf03p5lbicI9pFQH4pPW/TcwoqXUzosVVBmgEN Dxc+jwHQsM/N3w1/qjLpvA0pw1kzzzAfAoCtALo8f990Mh6CnGdkT0IF5 009D6Krpr8sIUYQPBn8lYqQUeXxSeedYiNAan7yO0pB8q76yXuqWwxy9T o=; Authentication-Results: esa5.hc3370-68.iphmx.com; dkim=none (message not signed) header.i=none IronPort-SDR: SiAzn9OIsIgZRt99hXoJrnj0p6vc15yfD1+wOwjJA4EiHCXHfVfKXkjywv87WApVHmD+aBJQCt fhsfjTIzs0NqR2OxpzpD4eB2nx48vIsznHmaHQ+OP8BDYicNtj7bpxCz7zvH1lwNIl62/5s/qx /1IZ9a5SqaGOUH/1c4Gqcpy4K5F44uhywSlBqY0hU7f3iCi8ox/bsQTIrLqbXOCH939MALTdMg 1CvEJ/FQGSguVlbXBXtLher8Io1nOqxKFz0wsC1K45QDJfzXRfrs2tRhQqYbEp3YRVCjxqqTvV VlY= X-SBRS: 2.7 X-MesageID: 22817687 X-Ironport-Server: esa5.hc3370-68.iphmx.com X-Remote-IP: 162.221.158.21 X-Policy: $RELAYED X-IronPort-AV: E=Sophos;i="5.75,362,1589256000"; d="scan'208";a="22817687" Date: Fri, 17 Jul 2020 16:41:39 +0200 From: Roger Pau =?utf-8?B?TW9ubsOp?= To: Bertrand Marquis Subject: Re: RFC: PCI devices passthrough on Arm design proposal Message-ID: <20200717144139.GU7191@Air-de-Roger> References: <3F6E40FB-79C5-4AE8-81CA-E16CA37BB298@arm.com> <28899FEF-9DA7-4513-8283-1AC5EFFC6E92@arm.com> <1dd5db2d-98c7-7738-c3d4-d3f098dfe674@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: AMSPEX02CAS02.citrite.net (10.69.22.113) To AMSPEX02CL02.citrite.net (10.69.22.126) X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Rahul Singh , Stefano Stabellini , Jan Beulich , "xen-devel@lists.xenproject.org" , nd , Julien Grall Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" On Fri, Jul 17, 2020 at 02:34:55PM +0000, Bertrand Marquis wrote: > > > > On 17 Jul 2020, at 16:06, Jan Beulich wrote: > > > > On 17.07.2020 15:59, Bertrand Marquis wrote: > >> > >> > >>> On 17 Jul 2020, at 15:19, Jan Beulich wrote: > >>> > >>> On 17.07.2020 15:14, Bertrand Marquis wrote: > >>>>> On 17 Jul 2020, at 10:10, Jan Beulich wrote: > >>>>> On 16.07.2020 19:10, Rahul Singh wrote: > >>>>>> # Emulated PCI device tree node in libxl: > >>>>>> > >>>>>> Libxl is creating a virtual PCI device tree node in the device tree to enable the guest OS to discover the virtual PCI during guest boot. We introduced the new config option [vpci="pci_ecam"] for guests. When this config option is enabled in a guest configuration, a PCI device tree node will be created in the guest device tree. > >>>>> > >>>>> I support Stefano's suggestion for this to be an optional thing, i.e. > >>>>> there to be no need for it when there are PCI devices assigned to the > >>>>> guest anyway. I also wonder about the pci_ prefix here - isn't > >>>>> vpci="ecam" as unambiguous? > >>>> > >>>> This could be a problem as we need to know that this is required for a guest upfront so that PCI devices can be assigned after using xl. > >>> > >>> I'm afraid I don't understand: When there are no PCI device that get > >>> handed to a guest when it gets created, but it is supposed to be able > >>> to have some assigned while already running, then we agree the option > >>> is needed (afaict). When PCI devices get handed to the guest while it > >>> gets constructed, where's the problem to infer this option from the > >>> presence of PCI devices in the guest configuration? > >> > >> If the user wants to use xl pci-attach to attach in runtime a device to a guest, this guest must have a VPCI bus (even with no devices). > >> If we do not have the vpci parameter in the configuration this use case will not work anymore. > > > > That's what everyone looks to agree with. Yet why is the parameter needed > > when there _are_ PCI devices anyway? That's the "optional" that Stefano > > was suggesting, aiui. > > I agree in this case the parameter could be optional and only required if not PCI device is assigned directly in the guest configuration. Where will the ECAM region(s) appear on the guest physmap? Are you going to re-use the same locations as on the physical hardware, or will they appear somewhere else? Roger.