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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A9A42C433EF for ; Wed, 20 Jul 2022 13:29:55 +0000 (UTC) Received: from localhost ([::1]:41142 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oE9ly-00080I-PX for qemu-devel@archiver.kernel.org; Wed, 20 Jul 2022 09:29:54 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:34800) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oE9e6-00025B-IL for qemu-devel@nongnu.org; Wed, 20 Jul 2022 09:21:46 -0400 Received: from mail.ilande.co.uk ([2001:41c9:1:41f::167]:51962) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oE9e3-0000Ch-Vv for qemu-devel@nongnu.org; Wed, 20 Jul 2022 09:21:46 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=ilande.co.uk; s=20220518; h=Subject:Content-Transfer-Encoding:Content-Type: In-Reply-To:From:References:To:MIME-Version:Date:Message-ID:Sender:Reply-To: Cc: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=F+OglXyQJRva7sHVZKIOykeWFiM+G3l1CkRHV0Dlggg=; b=RgPzxbN1P3VJcVjyTJ1prKm9uY Y8jMhhDHaLaIZFA2TEnCjgvvrvo2j5MD6CWP/XpAxIsejlNmJWzypIQnokgwZyemvdrLMEJQ7TTmv O+XEmeVZHB5Y7A+QLE6APGyqMsWAOGRss5T4AY1bHYalD+l7F1thIl03OenpgNlEY0HOGJpOJECpg 4/bBLFlT33GOpm8VrERJO0wb8ffo6GWLfhPra6T5OHThzc1sZXdGjhRgx7I8N4YP4XeKjSwVllI7x G7SqY7KkAYnPcKvvg0p7ufPg4J/+SgKLN8mfxvf8nG9jmRHbnEoNfKIoO6HxDsyguVTi2GBYvSGML 4mb9ih880SuKW54/1NwGOSpluQUI3xfMEB78OWyqhO6xBIKQS8J9BmYcM0gbh7GkLOHhLv7y1Vv7S PsoC5Jd0GWhHF6G+5ztw22K+i2rBnDHgVsUNk7bpQehiZnLXk3txea5QxWHV7LSppeIjtnzdvzXcu 5KPsLG5zaT387QLlUCsOfeFI6i/x3pS42WH7sfXr0ryzMVkYcDnPP3Y5Y7Us7jJEmgg8NfIl1EhFK qJPIZEFsWSWZhhgZ0COdNKrLGQw0J4h8sm4WpPuvUejxFVop2YVH8K7swRYBe+gGbQHk9YxzdO55t 5ow+Fi7N0Gy4kbFmAnv2Edc2C3T7zQ+LYM5s4gMAQ=; Received: from [2a00:23c4:8ba6:5100:d563:eb67:74b1:7b0] by mail.ilande.co.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1oE9ci-000APr-EQ; Wed, 20 Jul 2022 14:20:20 +0100 Message-ID: <5bc2fcee-2c5d-c400-5992-e2b4ce828477@ilande.co.uk> Date: Wed, 20 Jul 2022 14:21:38 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 Content-Language: en-US To: Roman Kagan , =?UTF-8?Q?Daniel_P=2e_Berrang=c3=a9?= , qemu-devel@nongnu.org, Vladimir Sementsov-Ogievskiy , Thomas Huth , Laurent Vivier , Marcel Apfelbaum , yc-core@yandex-team.ru, Paolo Bonzini , "Michael S. Tsirkin" References: <20220720102555.874394-1-rvkagan@yandex-team.ru> From: Mark Cave-Ayland In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 2a00:23c4:8ba6:5100:d563:eb67:74b1:7b0 X-SA-Exim-Mail-From: mark.cave-ayland@ilande.co.uk Subject: Re: [PATCH v3] hw/pci/pci_bridge: ensure PCIe slots have only one slot X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on mail.ilande.co.uk) Received-SPF: pass client-ip=2001:41c9:1:41f::167; envelope-from=mark.cave-ayland@ilande.co.uk; helo=mail.ilande.co.uk X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 20/07/2022 12:00, Roman Kagan wrote: > On Wed, Jul 20, 2022 at 11:44:26AM +0100, Daniel P. Berrangé wrote: >> On Wed, Jul 20, 2022 at 01:25:55PM +0300, Roman Kagan wrote: >>> It's possible to create non-working configurations by attaching a device >>> to a derivative of PCIe slot (pcie-root-port, ioh3420, etc) and >>> specifying a slot number other that zero, e.g.: >>> >>> -device pcie-root-port,id=s0,... \ >>> -device virtio-blk-pci,bus=s0,addr=4,... >>> >>> Make QEMU reject such configurations and only allow addr=0 on the >>> secondary bus of a PCIe slot. >> >> What do you mean by 'non-working' in this case. The guest OS boots >> OK, but I indeed don't see the device in the guest, but IIUC it was >> said that was just because Linux doesn't scan for a non-zero slot. > > Right. I don't remember if it was Linux or firmware or both but indeed > at least Linux guests don't see devices if attached to a PCIe slot at > addr != 0. (Which is kinda natural for a thing called "slot", isn't it?) > >> That wouldn't be a broken config from QEMU's POV though, merely a >> guest OS limitation ? > > Strictly speaking it wouldn't, indeed. But we've had created such a > configuration (due to a bug in our management layer) and spent > non-negligible time trying to figure out why the attached device didn't > appear in the guest. So I thought it made sense to reject a > configuration which is known to confuse guests. Doesn't it? This does seem a bit odd. What does the output of "info qtree" look like for your non-working configuration? ATB, Mark.