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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 77157C433EF for ; Wed, 13 Oct 2021 20:53:52 +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 3B60A61139 for ; Wed, 13 Oct 2021 20:53:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 3B60A61139 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.208860.365113 (Exim 4.92) (envelope-from ) id 1malFq-0005DO-Cv; Wed, 13 Oct 2021 20:53:38 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 208860.365113; Wed, 13 Oct 2021 20:53:38 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1malFq-0005DH-9A; Wed, 13 Oct 2021 20:53:38 +0000 Received: by outflank-mailman (input) for mailman id 208860; Wed, 13 Oct 2021 20:53:37 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1malFp-0005DB-9D for xen-devel@lists.xenproject.org; Wed, 13 Oct 2021 20:53:37 +0000 Received: from mail.kernel.org (unknown [198.145.29.99]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 14ffbdc5-08b4-496a-b4ff-6f7f40720dbb; Wed, 13 Oct 2021 20:53:36 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 618D061152; Wed, 13 Oct 2021 20:53:34 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 14ffbdc5-08b4-496a-b4ff-6f7f40720dbb DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1634158415; bh=4j/pbEyjS/pwpNumw3o26zquVKCWrgEEszXmjNxHzM0=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=VXiO48iiK+2PzFes5eC/WgZFsu9oTT/SuODLuxwXWAwM7EJcJXkz6FF7Gx4XBaSQQ c0xuWMDQrKio28HCEwtJVuw6yoFzkCtqkKFzR/3vPIUL2+x36kluJRGmbqrpnpZKDw uRejHTtNTABI/4nhU8/9WD2Efqf3rEPSSfrh2GnOPQyfEcKbFeqezIPHllA6AW6L43 rrFTjQuxBVLOZz3KzAr5W8ccdKrbAbUQf39iSt0q04WwqAxzz77OBbaUMeeA4smgEa MUPFIUdaUVH7VWgO/aozou3KMLQwQG+NwVZhxmju4IKs2YmCICWQdanl9uo4P8Czb7 E3lwK9TIStgyw== Date: Wed, 13 Oct 2021 13:53:33 -0700 (PDT) From: Stefano Stabellini X-X-Sender: sstabellini@sstabellini-ThinkPad-T480s To: =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= cc: Bertrand Marquis , Michal Orzel , Rahul Singh , "xen-devel@lists.xenproject.org" , Andre Przywara , Christian Lindig , David Scott , Ian Jackson , Wei Liu , Andrew Cooper , George Dunlap , Jan Beulich , Julien Grall , Stefano Stabellini , Volodymyr Babchuk Subject: Re: [PATCH v5 07/11] xen/domctl: Introduce XEN_DOMCTL_CDF_vpci flag In-Reply-To: Message-ID: References: <20d5b9d6a0d01a7b90711d28cbefb5701a88b438.1633540842.git.rahul.singh@arm.com> <9217a6b8-fc53-a049-7cd3-7458b574424b@arm.com> <8F9D6B9C-58CB-4000-995A-95517EE72A3B@arm.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: multipart/mixed; BOUNDARY="8323329-1296413107-1634152015=:9408" Content-ID: This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323329-1296413107-1634152015=:9408 Content-Type: text/plain; CHARSET=UTF-8 Content-Transfer-Encoding: 8BIT Content-ID: On Wed, 13 Oct 2021, Roger Pau Monné wrote: > > I think the second solution is the right one but it cannot be done so near from the > > feature freeze. > > > > The CDF flag as introduced right now is not creating any issue and will be used once > > the emulation flag will be introduce. We will be able at this stage to set this properly > > also on x86 (for dom0 pvh). > > Moreover keeping it will allow to continue to merge the remaining part of the PCI > > passthrough which are otherwise not possible to be done as they are dependent on this flag. > > > > Can we agree on keep the DOMCTL_CDF_vpci flag and introduce the emulation > > flag on Arm after 4.16 release ? > > If vPCI for Arm on 4.16 is not going to be functional, why so much > pressure in pushing those patches so fast? I understand the need to > remove stuff from the queue, but I don't think it's worth the cost of > introducing a broken interface deliberately on a release. > > I think we need to at least settle on whether we want to keep > CDF_vpci or use an arch specific signal mechanism in order to decide > what to do regarding the release. I wrote a longer separate email to provide more context about the "pushing fast" comment. I agree that we don't want to introduce a bad interface. In regards to a way forward for 4.16, my suggestion is the following: - revert this patch: do not change the interface in this series - do not change anything related to CDF_vpci for x86 - for ARM, leave has_vpci(d) to { false } and do not set XEN_DOMCTL_CDF_vpci - we can discuss it in depth later on, no rush - in patch #10, in libxl_arm.c:libxl__arch_domain_prepare_config - do not set XEN_DOMCTL_CDF_vpci - do not set b_info.arch_arm.vpci - do not define LIBXL_HAVE_BUILDINFO_ARM_VPCI in libxl.h - keep make_vpci_node and arch_arm.vpci The other patches (#1, #8, #10), which don't change any interfaces, can still make it for 4.16 if the review feedback is addressed on time, with one open TODO item [1]. This way, we get all the essential infrastructure we are trying to introduce without making any compromises on the external interfaces. Still it is good to have patches #1 #8 #10 so that with a trival oneliner patch on top of 4.16 we can enable PCI for ARM and do testing in the community, in gitlab-ci, and OSSTest too. (We have been discussing special OSSTest flights to valide PCI passthrough as we complete development.) If we think we need a snap decision on this topic, I am available for a quick sync-up call or IRC meeting between 8AM and 10AM tomorrow (Oct 14). [1] https://marc.info/?l=xen-devel&m=163412120531248 --8323329-1296413107-1634152015=:9408--