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 890A2C36002 for ; Mon, 24 Mar 2025 16:07:27 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1twkKI-0004g4-52; Mon, 24 Mar 2025 12:06:58 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1twkK1-0004cC-NW; Mon, 24 Mar 2025 12:06:43 -0400 Received: from frasgout.his.huawei.com ([185.176.79.56]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1twkJx-0004RT-EQ; Mon, 24 Mar 2025 12:06:40 -0400 Received: from mail.maildlp.com (unknown [172.18.186.31]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4ZLyWv73plz6K9WH; Tue, 25 Mar 2025 00:03:23 +0800 (CST) Received: from frapeml500008.china.huawei.com (unknown [7.182.85.71]) by mail.maildlp.com (Postfix) with ESMTPS id 4084D140723; Tue, 25 Mar 2025 00:06:33 +0800 (CST) Received: from frapeml500008.china.huawei.com (7.182.85.71) by frapeml500008.china.huawei.com (7.182.85.71) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Mon, 24 Mar 2025 17:06:33 +0100 Received: from frapeml500008.china.huawei.com ([7.182.85.71]) by frapeml500008.china.huawei.com ([7.182.85.71]) with mapi id 15.01.2507.039; Mon, 24 Mar 2025 17:06:33 +0100 To: Nicolin Chen , Eric Auger CC: Donald Dutile , "qemu-arm@nongnu.org" , "qemu-devel@nongnu.org" , "peter.maydell@linaro.org" , "jgg@nvidia.com" , "berrange@redhat.com" , "nathanc@nvidia.com" , "mochs@nvidia.com" , "smostafa@google.com" , Linuxarm , "Wangzhou (B)" , jiangkunkun , Jonathan Cameron , "zhangfei.gao@linaro.org" Subject: RE: [RFC PATCH v2 05/20] hw/arm/smmuv3-accel: Associate a pxb-pcie bus Thread-Topic: [RFC PATCH v2 05/20] hw/arm/smmuv3-accel: Associate a pxb-pcie bus Thread-Index: AQHbkps6in4QB/PMZUednFRw1zRmILN5b66AgADGVyCAAgfGgIAFxokwgABCuACAAC8TgIAAERjQ Date: Mon, 24 Mar 2025 16:06:32 +0000 Message-ID: <85fe1320d25b46189721f2a796f7da22@huawei.com> References: <20250311141045.66620-1-shameerali.kolothum.thodi@huawei.com> <20250311141045.66620-6-shameerali.kolothum.thodi@huawei.com> <3d1312b411f04121a3be90879a915982@huawei.com> <2f84490d309440a4a2ac56fd893ddab8@huawei.com> In-Reply-To: Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.203.177.241] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Received-SPF: pass client-ip=185.176.79.56; envelope-from=shameerali.kolothum.thodi@huawei.com; helo=frasgout.his.huawei.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H2=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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: , Reply-to: Shameerali Kolothum Thodi From: Shameerali Kolothum Thodi via Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org > -----Original Message----- > From: Nicolin Chen > Sent: Monday, March 24, 2025 4:02 PM > To: Eric Auger > Cc: Shameerali Kolothum Thodi > ; Donald Dutile > ; qemu-arm@nongnu.org; qemu-devel@nongnu.org; > peter.maydell@linaro.org; jgg@nvidia.com; berrange@redhat.com; > nathanc@nvidia.com; mochs@nvidia.com; smostafa@google.com; Linuxarm > ; Wangzhou (B) ; > jiangkunkun ; Jonathan Cameron > ; zhangfei.gao@linaro.org > Subject: Re: [RFC PATCH v2 05/20] hw/arm/smmuv3-accel: Associate a pxb- > pcie bus >=20 > On Mon, Mar 24, 2025 at 02:13:20PM +0100, Eric Auger wrote: > > >> If VM has an emulated device and a passthrough device: > > >> attach the emulated device to PCIE.0 <=3D> vSMMU bypass (or > accel=3Doff?) > > >> attach the passthrough device to pxb-pcie <=3D> vSMMU0 (accel=3Don) > > > This can be other way around as well: > > > ie, > > > pass-through to pcie.0(accel=3Don) and emulated to any other pxb-pcie > with accel =3D off. > > +1 > > > > > > I think the way bus numbers are allocated in Qemu for pcie.0 and pxb- > pcie allows > > > us to support this in IORT ID maps. > > One trouble we may get into is possible bus reordering by the guest. I > > don't know the details but I remember that in certain conditions the > > guest can reorder the bus numbers. >=20 > Hmm, that sounds troublesome. IORT mappings are done using the bus > number, which is fixed to a vSMMU. Can we disable that reordering? DSM 5# is actually a way to do that. But I don't think we need that as host kernel also will have the same issues with IORT if re enumeration happens. I think the iommu_fwspec mechanism is to take care of this. I need to doubl= e check though. =20 Thanks, Shameer