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 01DA8C0218F for ; Fri, 31 Jan 2025 14:41:21 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tdsBt-0003zU-DJ; Fri, 31 Jan 2025 09:40:17 -0500 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 1tdsBn-0003xR-8t; Fri, 31 Jan 2025 09:40:12 -0500 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 1tdsBk-0001sL-5b; Fri, 31 Jan 2025 09:40:10 -0500 Received: from mail.maildlp.com (unknown [172.18.186.31]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4Ykz554C6vz6D94X; Fri, 31 Jan 2025 22:37:45 +0800 (CST) Received: from frapeml500005.china.huawei.com (unknown [7.182.85.13]) by mail.maildlp.com (Postfix) with ESMTPS id 14CAF140B25; Fri, 31 Jan 2025 22:39:54 +0800 (CST) Received: from frapeml500008.china.huawei.com (7.182.85.71) by frapeml500005.china.huawei.com (7.182.85.13) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Fri, 31 Jan 2025 15:39:53 +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; Fri, 31 Jan 2025 15:39:53 +0100 To: Jason Gunthorpe CC: =?iso-8859-1?Q?Daniel_P=2E_Berrang=E9?= , "qemu-arm@nongnu.org" , "qemu-devel@nongnu.org" , "eric.auger@redhat.com" , "peter.maydell@linaro.org" , "nicolinc@nvidia.com" , "ddutile@redhat.com" , Linuxarm , "Wangzhou (B)" , jiangkunkun , Jonathan Cameron , "zhangfei.gao@linaro.org" , Nathan Chen Subject: RE: [RFC PATCH 0/5] hw/arm/virt: Add support for user-creatable nested SMMUv3 Thread-Topic: [RFC PATCH 0/5] hw/arm/virt: Add support for user-creatable nested SMMUv3 Thread-Index: AQHbMeB0+Q5BEZc9JkeH/U6Jz+dF4rMv66IAgAA0HqCAAPMSYIAAUDgAgAAS6wA= Date: Fri, 31 Jan 2025 14:39:53 +0000 Message-ID: <3efcea1171af4b2f81be842f2c55fe51@huawei.com> References: <20241108125242.60136-1-shameerali.kolothum.thodi@huawei.com> <7ecabe74e0514367baf28d67675e5db8@huawei.com> <20250131142404.GP5556@nvidia.com> In-Reply-To: <20250131142404.GP5556@nvidia.com> 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="iso-8859-1" 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_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_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: Jason Gunthorpe > Sent: Friday, January 31, 2025 2:24 PM > To: Shameerali Kolothum Thodi > Cc: Daniel P. Berrang=E9 ; qemu-arm@nongnu.org; > qemu-devel@nongnu.org; eric.auger@redhat.com; > peter.maydell@linaro.org; nicolinc@nvidia.com; ddutile@redhat.com; > Linuxarm ; Wangzhou (B) > ; jiangkunkun ; > Jonathan Cameron ; > zhangfei.gao@linaro.org; Nathan Chen > Subject: Re: [RFC PATCH 0/5] hw/arm/virt: Add support for user-creatable > nested SMMUv3 >=20 > On Fri, Jan 31, 2025 at 09:33:16AM +0000, Shameerali Kolothum Thodi > wrote: >=20 > > And Qemu does some checking to make sure that the device is indeed > associated > > with the specified phys-smmuv3. This can be done going through the > sysfs path checking > > which is what I guess libvirt is currently doing to populate the topolo= gy. > So basically > > Qemu is just replicating that to validate again. >=20 > I would prefer that iommufd users not have to go out to sysfs.. >=20 > > Or another option is extending the IOMMU_GET_HW_INFO IOCTL to > return the phys > > smmuv3 base address which can avoid going through the sysfs. >=20 > It also doesn't seem great to expose a physical address. But we could > have an 'iommu instance id' that was a unique small integer? Ok. But how the user space can map that to the device? Something like, /sys/bus/pci/devices/0000:7d:00.1/iommu/instance.X ? Thanks, Shameer