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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 9CA7CC47404 for ; Thu, 10 Oct 2019 02:07:04 +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 55CA720B7C for ; Thu, 10 Oct 2019 02:07:04 +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="mx+mxcwH" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 55CA720B7C 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]:33278 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iINr5-00069d-5I for qemu-devel@archiver.kernel.org; Wed, 09 Oct 2019 22:07:03 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:52327) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iINpH-0004uC-Tk for qemu-devel@nongnu.org; Wed, 09 Oct 2019 22:05:13 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iINpG-0003pG-A5 for qemu-devel@nongnu.org; Wed, 09 Oct 2019 22:05:11 -0400 Received: from bilbo.ozlabs.org ([203.11.71.1]:57101 helo=ozlabs.org) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iINpF-0003na-Dt; Wed, 09 Oct 2019 22:05:10 -0400 Received: by ozlabs.org (Postfix, from userid 1007) id 46pZCw4y1mz9sPd; Thu, 10 Oct 2019 13:05:00 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gibson.dropbear.id.au; s=201602; t=1570673100; bh=SEBTGwcqOgFUeQKFQIgzM1k/N945vi3PtbA8R0cv6aQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=mx+mxcwHJx/p3zHNJOAaEDzLH8gy9DtPIhLFNA6/kZQuiSFhKwPOcecq032jznpgP oilC2f807tr1jD7hnnPUgjUibtfetpDZMYF11Die+8r7hEJfLBkhgWpTBlvWGUyOEJ qkIHh7sMvocfpj/RB8jgT2+zLnHSmeTigfaXBW6M= Date: Thu, 10 Oct 2019 13:02:39 +1100 From: David Gibson To: Greg Kurz Subject: Re: [PATCH v4 19/19] spapr: Work around spurious warnings from vfio INTx initialization Message-ID: <20191010020239.GD28552@umbus.fritz.box> References: <20191009060818.29719-1-david@gibson.dropbear.id.au> <20191009060818.29719-20-david@gibson.dropbear.id.au> <20191009103738.01bc146a@bahia.lan> <20191009085259.GA5035@umbus.fritz.box> <20191009191639.4055f811@bahia.lan> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="/unnNtmY43mpUSKx" Content-Disposition: inline In-Reply-To: <20191009191639.4055f811@bahia.lan> User-Agent: Mutt/1.12.1 (2019-06-15) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 203.11.71.1 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: Alexey Kardashevskiy , Jason Wang , Riku Voipio , qemu-devel@nongnu.org, Laurent Vivier , Alex Williamson , qemu-ppc@nongnu.org, clg@kaod.org, Paolo Bonzini , =?iso-8859-1?Q?Marc-Andr=E9?= Lureau , philmd@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --/unnNtmY43mpUSKx Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Oct 09, 2019 at 07:16:39PM +0200, Greg Kurz wrote: > On Wed, 9 Oct 2019 19:52:59 +1100 > David Gibson wrote: >=20 > > On Wed, Oct 09, 2019 at 10:37:38AM +0200, Greg Kurz wrote: > > > On Wed, 9 Oct 2019 17:08:18 +1100 > > > David Gibson wrote: > > >=20 > > > > Traditional PCI INTx for vfio devices can only perform well if using > > > > an in-kernel irqchip. Therefore, vfio_intx_update() issues a warni= ng > > > > if an in kernel irqchip is not available. > > >=20 > > > Can you elaborate on what doesn't "perform well" without an > > > in-kernel irqchip ? > >=20 > > Not really, no, but Alex Williamson tells me it is soo. > >=20 > > > Is it a matter of performance or is it > > > actually broken or something else ? > >=20 > > I believe it's a matter of performance, but such a big one that it > > makes using it without kernel irqchip infeasible in many cases. > >=20 > > > What is the impact on -machine accel=3Dkvm,kernel-irqchip=3Doff which > > > always spit this warning ? > >=20 > > It should still spit that warning. > >=20 >=20 > Yeah of course it does, but it is expected that we cannot setup > the irqfd since we deliberately don't have an in-kernel irqchip, > isn't it ? Why spit a warning in this case ? Or is it just a not > very user friendly way of saying "you will have poor performance > if the VFIO device uses PCI INTx" ? The last thing, AIUI. --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --/unnNtmY43mpUSKx Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEdfRlhq5hpmzETofcbDjKyiDZs5IFAl2ekT8ACgkQbDjKyiDZ s5L1yRAAyDLQ2mtRSuaYYXS+7txIbQ18DffN56rqSVAd39j4OpX7Zb5Im5QFmSfw PphmxQ0yhNWSlaqFr+CTyaE3DFHHRqTtswfIchqDR8Eqr0zKHq4FvBJpXyapEdel PiqTI6eR1/wtbna2Q/q5UMGOF9A+ACcS6CQMlZFJpueRDTqQMVx+zlmduUC3ohLR 57IfDI6pkP7+M6tXzZX+UEz2LY7dSRiJNo4Is6I3NJGbKDqkFRMLJSCFwmXwrNLB DA5qBdDRBdttZ5cRxc2NGlaNQ6n0RIaVFykQ5W7u5XyxUXrUUYQxVUZQoXfSVwO/ KrOpwG7246Sq/Rk0/o+xryXeptIZOPxbs+9uIDAmxiYfJzjNE7qdO1VJ+Yflo/yY fll0cvtR5XKeTmJZRig1SLst7N/Up8hhBMwJgV8AIrzYMAJu84mB5DNDPwHHVmHo sRvA+PWGE4UCNqrXl1eZYIuO2g3wceBCb7KE1aDjJskKOPAw4XFwCVDckfN9w5vj Wghne9pnlwtAYFvSSca0LD+01/SKBAlaTOvKHEl1PkdLjdz+Z4UocfWlePGN2k0O XqYp0nxjtad4RQNlonzEX08kkWL/ADPOTPmiawdQnSXnePuaB1vuAFJm+ccQGLl0 rCBbfDjK3AxlzGwQA0GlgzLNEeO07Rori/UjVVQ9fNeWFQ6RhUc= =q2Gm -----END PGP SIGNATURE----- --/unnNtmY43mpUSKx--