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 A45F7C433F5 for ; Wed, 30 Mar 2022 17:13:57 +0000 (UTC) Received: from localhost ([::1]:43372 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nZbtM-0006kH-Ms for qemu-devel@archiver.kernel.org; Wed, 30 Mar 2022 13:13:56 -0400 Received: from eggs.gnu.org ([209.51.188.92]:59198) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nZbsd-0005kj-HQ for qemu-devel@nongnu.org; Wed, 30 Mar 2022 13:13:11 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:45310) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nZbsa-0004Yh-Fg for qemu-devel@nongnu.org; Wed, 30 Mar 2022 13:13:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1648660387; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=atmD6INaNepSjRwGDrj7z7GXK7PzqtJINZVZtxNiiSo=; b=Olu8FU/TUogM9OvlVrrSksFn2xneRUSHbX1CE2xLcPQ5i0jJb4q2PD/r/KQZsoESpC1kKJ B8iaBHcpPmwCdPsJlMywkqLT3QG+M3w1DPS1z4oAX3TWg+E2Aj82GOQ9QBLR7Q5klP8eL1 Q9P+jNloXLAtqi02TRw2zl4k2Gjx2GU= Received: from mail-qv1-f71.google.com (mail-qv1-f71.google.com [209.85.219.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-453-NfG_90OTPfu7PYIFihyHpA-1; Wed, 30 Mar 2022 13:13:05 -0400 X-MC-Unique: NfG_90OTPfu7PYIFihyHpA-1 Received: by mail-qv1-f71.google.com with SMTP id q4-20020a0cf5c4000000b0044346ee3627so8373776qvm.16 for ; Wed, 30 Mar 2022 10:13:05 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=atmD6INaNepSjRwGDrj7z7GXK7PzqtJINZVZtxNiiSo=; b=k11ooSqZ+jwxDV5//evi5ajW7lgFydpo29PBr3nHiwGA4HPfZY/GMzcWtxC7reIEeN hYxJ+2iQIRueZHsdk4bJAOklMBDQe2iXXXBLkA+RJaSUQNU4y4lOYMvcMrqrugN7eNE3 0ZZ74Dc7f7u9LHk6CG9eB+p8HWXomxpvwplLa0N66XJ5Z5G4LkS0R0SQBJ2x4NpKu/CK MBM2m0GX76dRIQ1P0nZvRNXDF5GlXm5mWqXM/svSkDIZwSptc0q29APKqrZ2MBWOBNLZ E1jE6Bzz5OX+Td2uGCO6vKeI+D30t6wIrN3Od2Whu9F4w3smJRzkduCS7U3mfu1RZmOC D2sA== X-Gm-Message-State: AOAM532voKP4XosLHLpRH/LLlNlbpyvtNABRJN3aZbtozPD2Hhq3uhjn YnkIRch8BtbrsheacWNpFqyBusn9SPyI/GsTYsNDNJKICEvCG3tR8lC/3VD8GfaBqQaMLNwjutm O+RAYP2nUf0y/g3Q= X-Received: by 2002:a05:622a:1742:b0:2e1:ecf4:900c with SMTP id l2-20020a05622a174200b002e1ecf4900cmr491220qtk.473.1648660385259; Wed, 30 Mar 2022 10:13:05 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxirauhqDDiZbRf6bZi3KFm/nncrcCk1n+7rkXq1bW/cmAimQdtyyggimcpj7rnO8jyaEwl7A== X-Received: by 2002:a05:622a:1742:b0:2e1:ecf4:900c with SMTP id l2-20020a05622a174200b002e1ecf4900cmr491181qtk.473.1648660384984; Wed, 30 Mar 2022 10:13:04 -0700 (PDT) Received: from xz-m1.local (cpec09435e3e0ee-cmc09435e3e0ec.cpe.net.cable.rogers.com. [99.241.198.116]) by smtp.gmail.com with ESMTPSA id x18-20020a05622a001200b002eb856d7786sm6527953qtw.84.2022.03.30.10.13.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Mar 2022 10:13:04 -0700 (PDT) Date: Wed, 30 Mar 2022 13:13:03 -0400 From: Peter Xu To: Stefan Hajnoczi Subject: Re: [PATCH v7 12/17] vfio-user: IOMMU support for remote device Message-ID: References: <2fdb90acd40a1f79d571d4e68c56e6b08aded60d.1648234157.git.jag.raman@oracle.com> <7022E4C4-D71A-4A6E-A5D8-222A9462654C@oracle.com> MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=170.10.129.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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: , Cc: "eduardo@habkost.net" , Elena Ufimtseva , John Johnson , Jag Raman , "bleal@redhat.com" , "john.levon@nutanix.com" , "Michael S. Tsirkin" , "armbru@redhat.com" , Jason Wang , "quintela@redhat.com" , "f4bug@amsat.org" , qemu-devel , Alex Williamson , Kanth Ghatraju , "berrange@redhat.com" , "thanos.makatos@nutanix.com" , "pbonzini@redhat.com" , "eblake@redhat.com" , "dgilbert@redhat.com" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Mar 30, 2022 at 05:08:24PM +0100, Stefan Hajnoczi wrote: > On Wed, Mar 30, 2022 at 08:53:16AM -0400, Peter Xu wrote: > > On Wed, Mar 30, 2022 at 11:04:24AM +0100, Stefan Hajnoczi wrote: > > > This makes me wonder whether there is a deeper issue with the > > > pci_setup_iommu() API: the lack of per-device cleanup callbacks. > > > Per-device IOMMU resources should be freed when a device is hot > > > unplugged. > > > > > > From what I can tell this is not the case today: > > > > > > - hw/i386/intel_iommu.c:vtd_find_add_as() allocates and adds device > > > address spaces but I can't find where they are removed and freed. > > > VTDAddressSpace instances pointed to from vtd_bus->dev_as[] are leaked. > > > > > > - hw/i386/amd_iommu.c has similar leaks. > > > > AFAICT it's because there's no device-specific data cached in the > > per-device IOMMU address space, at least so far. IOW, all the data > > structures allocated here can be re-used when a new device is plugged in > > after the old device unplugged. > > > > It's definitely not ideal since after unplug (and before a new device > > plugged in) the resource is not needed at all so it's kind of wasted, but > > it should work functionally. If to achieve that, some iommu_unplug() or > > iommu_cleanup() hook sounds reasonable. > > I guess the question is whether PCI busses can be hotplugged with > IOMMUs. If yes, then there is a memory leak that matters for > intel_iommu.c and amd_iommu.c. It can't, and we only support one vIOMMU so far for both (commit 1b3bf13890fd849b26). Thanks, -- Peter Xu