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 6CE77C02196 for ; Thu, 6 Feb 2025 08:55:49 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tfxfS-0001SQ-6Z; Thu, 06 Feb 2025 03:55:26 -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 1tfxfD-0001PA-3s for qemu-devel@nongnu.org; Thu, 06 Feb 2025 03:55:12 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tfxf8-0002q4-Mt for qemu-devel@nongnu.org; Thu, 06 Feb 2025 03:55:10 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1738832104; 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=/7DMP8RCz4MtWOgriPg2r75pBWlGZv8A4jVtyT4iTTM=; b=KzlikL7NligxBy+tws/ONDnB7zjv0AvcY2IMjglF+XQIZRGGjvdtY/GLqP1xzsms/HwQDB KT8WEqhVV0Vr9DYb+wh3Fn80cqrUN0GpaW0eTEVgUJl2+dUs7LHqkHC6EIPZF9rJSalD/M HIMHg79uXqGSpkMxNaSHnpFoeqq2wfE= 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-562-tJbHVk_wPJapAgkX5lJ0Nw-1; Thu, 06 Feb 2025 03:54:58 -0500 X-MC-Unique: tJbHVk_wPJapAgkX5lJ0Nw-1 X-Mimecast-MFC-AGG-ID: tJbHVk_wPJapAgkX5lJ0Nw Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (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 C70941955DDD; Thu, 6 Feb 2025 08:54:54 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.33]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9027D1800570; Thu, 6 Feb 2025 08:54:50 +0000 (UTC) Date: Thu, 6 Feb 2025 08:54:46 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Nathan Chen Cc: eric.auger@redhat.com, "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" , Shameer Kolothum , Jason Gunthorpe 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> <5709592d-cd1c-4894-a1d4-c0c4c61a2e07@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <5709592d-cd1c-4894-a1d4-c0c4c61a2e07@nvidia.com> User-Agent: Mutt/2.2.13 (2024-03-09) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Received-SPF: pass client-ip=170.10.133.124; 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_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=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 Wed, Feb 05, 2025 at 12:53:42PM -0800, Nathan Chen wrote: > > > On 1/31/2025 8:08 AM, Eric Auger 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? > > > > Eric > > Daniel mentions that the host-to-guest SMMU pairing must be chosen such that > it makes conceptual sense w.r.t. the guest NUMA to host NUMA pairing [0]. > The current implementation allows for incorrect host to guest numa node > pairings, e.g. pSMMU has affinity to host numa node 0, but it’s paired with > a vSMMU paired with a guest numa node pinned to host numa node 1. > > By specifying the host SMMU id, we can explicitly pair a host SMMU with a > guest SMMU associated with the correct PXB NUMA node, vs. implying the > host-to-guest SMMU pairing based on what devices are attached to the PXB. > While it would not completely prevent the incorrect pSMMU/vSMMU pairing > w.r.t. host to guest numa node pairings, specifying the pSMMU id would make > the implications of host to guest numa node pairings more clear when > specifying a vSMMU instance. You've not specified any host SMMU id in the above CLI args though, only the PXB association. It needs something like -device arm-smmuv3-accel,bus=pcie.1,id=smmuv1,host-smmu=XXXXX where 'XXXX' is some value to identify the host SMMU 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 :|