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 4F1B8C433E1 for ; Fri, 17 Jul 2020 00:10:58 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 176AF206F4 for ; Fri, 17 Jul 2020 00:10:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=gibson.dropbear.id.au header.i=@gibson.dropbear.id.au header.b="m9Q5rm/a" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 176AF206F4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=gibson.dropbear.id.au Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:52900 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jwDxp-00047l-Da for qemu-devel@archiver.kernel.org; Thu, 16 Jul 2020 20:10:57 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:35286) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jwDvS-0001SC-0p; Thu, 16 Jul 2020 20:08:30 -0400 Received: from ozlabs.org ([2401:3900:2:1::2]:57473) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jwDvO-0001j3-2L; Thu, 16 Jul 2020 20:08:29 -0400 Received: by ozlabs.org (Postfix, from userid 1007) id 4B7BKd1mmpz9sRN; Fri, 17 Jul 2020 10:08:21 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gibson.dropbear.id.au; s=201602; t=1594944501; bh=2vx06zp73wz3Ol1Zy6rKplIQTC2vMPbjd/OKSA2mZPM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=m9Q5rm/a5D+WlTbyGyL4x6OW4jnsdPXj2q1u8W0jopVplJLh6Kc9JIvN5oHkRAWHm GGSz0TRtKyUHv3jnaoA32yUsHzUG9JNrqFH1/h+LM4x9Z5dVFOSSmCEkqdXHPkXQB1 PUe6IhT4Nbvero5F3KJ7WIZyYesf/N9k86q2Qzgs= Date: Fri, 17 Jul 2020 09:57:31 +1000 From: David Gibson To: Greg Kurz Subject: Re: [PATCH] spapr_pci: Robustify support of PCI bridges Message-ID: <20200716235731.GD5607@umbus.fritz.box> References: <159431476748.407044.16711294833569014964.stgit@bahia.lan> <20200716044540.GL93134@umbus.fritz.box> <20200716123244.1f854c63@bahia.lan> <20200716131109.GA5607@umbus.fritz.box> <87r1tblerr.fsf@dusky.pond.sub.org> <20200716165754.50af735a@bahia.lan> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="MAH+hnPXVZWQ5cD/" Content-Disposition: inline In-Reply-To: <20200716165754.50af735a@bahia.lan> Received-SPF: pass client-ip=2401:3900:2:1::2; envelope-from=dgibson@ozlabs.org; helo=ozlabs.org X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. X-Spam_score_int: -9 X-Spam_score: -1.0 X-Spam_bar: - X-Spam_report: (-1.0 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HEADER_FROM_DIFFERENT_DOMAINS=1, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Thomas Huth , "Michael S. Tsirkin" , Markus Armbruster , qemu-devel@nongnu.org, qemu-ppc@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --MAH+hnPXVZWQ5cD/ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Jul 16, 2020 at 04:57:54PM +0200, Greg Kurz wrote: > On Thu, 16 Jul 2020 16:23:52 +0200 > Markus Armbruster wrote: >=20 > > David Gibson writes: > >=20 > > > On Thu, Jul 16, 2020 at 12:32:44PM +0200, Greg Kurz wrote: > > >> On Thu, 16 Jul 2020 14:45:40 +1000 > > >> David Gibson wrote: > > >>=20 > > >> > On Thu, Jul 09, 2020 at 07:12:47PM +0200, Greg Kurz wrote: > > >> > > Some recent error handling cleanups unveiled issues with our sup= port of > > >> > > PCI bridges: > > >> > >=20 > > >> > > 1) QEMU aborts when using non-standard PCI bridge types, > > >> > > unveiled by commit 7ef1553dac "spapr_pci: Drop some dead erro= r handling" > > >> > >=20 > > >> > > $ qemu-system-ppc64 -M pseries -device pcie-pci-bridge > > >> > > Unexpected error in object_property_find() at qom/object.c:1240: > > >> > > qemu-system-ppc64: -device pcie-pci-bridge: Property '.chassis_n= r' not found > > >> > > Aborted (core dumped) > > >> >=20 > > >> > Oops, I thought we had a check that we actually had a "pci-bridge" > > >> > device before continuing with the hotplug, but I guess not. > > >>=20 > > >> Ah... are you suggesting we should explicitly check the actual type > > >> of the bridge rather than looking for the "chassis_nr" property ? > > > > > > Uh.. I thought about it, but I don't think it matters much which way > > > we do it. > >=20 > > Would it make sense to add the "chassis_nr" property to *all* PCI > > bridge devices? > >=20 >=20 > I see that the "PCI Express to PCI/PCI-X Bridge Specification" mentions > a "Chassis Number Register" which looks very similar to the what exists > in standard PCI-to-PCI brdiges. This doesn't seem to be implemented in > our "pcie-pci-bridge" device model though, but of course I have no idea > why :) We could consider it, but I don't think there's a lot to be gained by it at this stage. I don't think there's really any reason to want to use bridges other than plain "pci-bridge" on the pseries machine. PCI is a bit weird on pseries, since it's explicitly paravirt. Although you can use extended config space, and thereby PCI-E devices on it, the topology really looks pretty much identical to vanilla PCI. So, I don't think there's any reason to use PCI-E bridges on pseries. Other than PCI-E bridges of various sorts, a quick scan suggests all the other bridge types in qemu are weird variants that are mostly specific to some particular platform. I don't see any reason we'd want those on pseries either. > Maybe Michael or Marcel (cc'd) can share some thoughts about that ? --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. 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