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 43DD2C02196 for ; Thu, 6 Feb 2025 08:54:45 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tfxdn-0000br-CC; Thu, 06 Feb 2025 03:53:43 -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 1tfxdh-0000Zv-OS for qemu-devel@nongnu.org; Thu, 06 Feb 2025 03:53:37 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tfxdf-00024C-Fk for qemu-devel@nongnu.org; Thu, 06 Feb 2025 03:53:37 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1738832014; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Y9aSj/VuNwxZGgwSzoXkriZH4fSXHhSnSQO9kCcVPbw=; b=XHbhJJwwVYGAdAMPtkmOHhuZ6yw7K3NbN9UApS5u0icJShe7+t6fQ8WR8IUJvWlNMrl+W9 Ii3Fyy8b1CMO1h/wXkSWi0lKRtypwYCaWCBQNrygkfC4v9KOt5dPa04pvU87guwD4Iw5k8 rDDHCZjeeA5pgiJHIMR64FGCsEK8l80= Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-99-VZ7RVb72PVm_FQqv3EEVzw-1; Thu, 06 Feb 2025 03:53:31 -0500 X-MC-Unique: VZ7RVb72PVm_FQqv3EEVzw-1 X-Mimecast-MFC-AGG-ID: VZ7RVb72PVm_FQqv3EEVzw Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 4710C1955D4F; Thu, 6 Feb 2025 08:53:28 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.33]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9D27430001AB; Thu, 6 Feb 2025 08:53:21 +0000 (UTC) Date: Thu, 6 Feb 2025 08:53:17 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Eric Auger Cc: Shameerali Kolothum Thodi , Jason Gunthorpe , "qemu-arm@nongnu.org" , "qemu-devel@nongnu.org" , "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 Message-ID: References: <20241108125242.60136-1-shameerali.kolothum.thodi@huawei.com> <7ecabe74e0514367baf28d67675e5db8@huawei.com> <20250131142404.GP5556@nvidia.com> <3efcea1171af4b2f81be842f2c55fe51@huawei.com> <20250131145411.GR5556@nvidia.com> <20039bbc40df453a8a41a863d74b9ff9@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/2.2.13 (2024-03-09) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=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=unavailable 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: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Fri, Jan 31, 2025 at 05:08:28PM +0100, Eric Auger wrote: > Hi, > > > On 1/31/25 4:23 PM, Shameerali Kolothum Thodi wrote: > > > >> -----Original Message----- > >> From: Jason Gunthorpe > >> Sent: Friday, January 31, 2025 2:54 PM > >> To: Shameerali Kolothum Thodi > >> Cc: Daniel P. Berrangé ; 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 > >> > >> On Fri, Jan 31, 2025 at 02:39:53PM +0000, Shameerali Kolothum Thodi > >> wrote: > >> > >>>>> 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 > >> topology. > >>>> So basically > >>>>> Qemu is just replicating that to validate again. > >>>> I would prefer that iommufd users not have to go out to sysfs.. > >>>> > >>>>> 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. > >>>> 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? > >> Why does it need to? > >> > >> libvirt picks some label for the vsmmu instance, it doesn't matter > >> what the string is. > >> > >> qemu validates that all of the vsmmu instances are only linked to PCI > >> device that have the same iommu ID. This is already happening in the > >> kernel, it will fail attaches to mismatched instances. > >> > >> Nothing further is needed? > > -device pxb-pcie,id=pcie.1,bus_nr=8,bus=pcie.0 \ > > -device pcie-root-port,id=pcie.port1,bus=pcie.1,chassis=1 \ > > -device arm-smmuv3-accel,bus=pcie.1,id=smmuv1 \ > I don't get what is the point of adding such an id if it is not > referenced anywhere? Every QDev device instance has an 'id' property - if you don't set one explicitly, QEMU will generate one internally. Libvirt will always set the 'id' property to avoid the internal auto- generated IDs, as it wants full knowledge of naming. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|