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=-12.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 AD8C1C433B4 for ; Fri, 9 Apr 2021 08:16:49 +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 6DE22611AD for ; Fri, 9 Apr 2021 08:16:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6DE22611AD Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.107680.205807 (Exim 4.92) (envelope-from ) id 1lUmJf-0007ev-Cs; Fri, 09 Apr 2021 08:16:35 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 107680.205807; Fri, 09 Apr 2021 08:16:35 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lUmJf-0007eo-9Z; Fri, 09 Apr 2021 08:16:35 +0000 Received: by outflank-mailman (input) for mailman id 107680; Fri, 09 Apr 2021 08:16:33 +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 1lUmJd-0007ej-Nb for xen-devel@lists.xenproject.org; Fri, 09 Apr 2021 08:16:33 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 47bb7726-d768-411c-81e5-a53ef148c778; Fri, 09 Apr 2021 08:16:32 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 19461AFF2; Fri, 9 Apr 2021 08:16:32 +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: 47bb7726-d768-411c-81e5-a53ef148c778 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1617956192; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1mNZEOqQAy+ATL6Tydb56njuwQFMfru48PyX5E2zoGw=; b=EfcJxKCbjbZHzaaePt9zcKCLHbOVU798Xe+sl/ore9ksJspcKUdg2EEnV9+JHHFnrRzEJ5 rSFo8adaDEf1p0VYJNlTB+DQr2KP9/ZEdjEmWVj7ehvR5osqb2Lwkc/msVDk1yNnITOE1v xiHcwB7P2bnfKJfi6VtK/v8juaSpXvA= Subject: Re: [PATCH 1/3] xen-pciback: redo VF placement in the virtual topology To: Boris Ostrovsky Cc: Juergen Gross , Konrad Wilk , "xen-devel@lists.xenproject.org" References: <32d6a8d4-c06f-7fe0-1376-4b80fac8c6de@suse.com> From: Jan Beulich Message-ID: <4e39de85-1b03-0fb4-805a-69a16bbaafa6@suse.com> Date: Fri, 9 Apr 2021 10:16:31 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 09.04.2021 00:28, Boris Ostrovsky wrote: > > On 4/7/21 10:37 AM, Jan Beulich wrote: >> The commit referenced below was incomplete: It merely affected what >> would get written to the vdev- xenstore node. The guest would still >> find the function at the original function number as long as >> __xen_pcibk_get_pci_dev() wouldn't be in sync. The same goes for AER wrt >> __xen_pcibk_get_pcifront_dev(). >> >> Undo overriding the function to zero and instead make sure that VFs at >> function zero remain alone in their slot. This has the added benefit of >> improving overall capacity, considering that there's only a total of 32 >> slots available right now (PCI segment and bus can both only ever be >> zero at present). >> >> Fixes: 8a5248fe10b1 ("xen PV passthru: assign SR-IOV virtual functions to separate virtual slots") >> Signed-off-by: Jan Beulich >> Cc: stable@vger.kernel.org >> --- >> Like the original change this has the effect of changing where devices >> would appear in the guest, when there are multiple of them. I don't see >> an immediate problem with this, but if there is we may need to reduce >> the effect of the change. >> Taking into account, besides the described breakage, how xen-pcifront's >> pcifront_scan_bus() works, I also wonder what problem it was in the >> first place that needed fixing. It may therefore also be worth to >> consider simply reverting the original change. > > > Perhaps this is no longer a problem, it's been 9 years since that patch. Have you tried reverting to 8a5248fe10b101104d92d01438f918e899414fd1~1 and testing that? Well, no, for the simple reason that I don't really understand how that change was meant to make a difference. Hence while simply reverting may be an option, it's not something I would want to suggest myself (simply because I couldn't fully justify doing so). Jan