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 27B92CCA473 for ; Wed, 15 Jun 2022 10:09:11 +0000 (UTC) Received: from localhost ([::1]:35212 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1o1PxV-00030c-UF for qemu-devel@archiver.kernel.org; Wed, 15 Jun 2022 06:09:09 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:43646) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1o1Pry-0007EU-Er for qemu-devel@nongnu.org; Wed, 15 Jun 2022 06:03:26 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:43492) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1o1Prr-0007Z2-BX for qemu-devel@nongnu.org; Wed, 15 Jun 2022 06:03:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1655287397; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=yS6/qgmZGSaTKVSa30+LowVbSJleX3Qbq904PnHtp08=; b=Ap5XCPuNc9UTmhbXIvGvSiIvxUbB01LexdrIYK2qDMGD/D9mHGPUs9x8hGnMXWjYhdtZSj PBwQGQ+6G1avR3JjcYw3cQw2L4AVdyZzA+5+7r+ZzXgrxZtHAkSzRFaIc+a+o4kw6PsU5h cAzpM2aajHrAuYQ5lgOzq+wEuhj9kW8= Received: from mail-qk1-f198.google.com (mail-qk1-f198.google.com [209.85.222.198]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-344-_QVnn42xM7-aCbLZYkwtyA-1; Wed, 15 Jun 2022 06:03:16 -0400 X-MC-Unique: _QVnn42xM7-aCbLZYkwtyA-1 Received: by mail-qk1-f198.google.com with SMTP id s8-20020a05620a0bc800b006a6d42a1a0eso9690694qki.3 for ; Wed, 15 Jun 2022 03:03:16 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=yS6/qgmZGSaTKVSa30+LowVbSJleX3Qbq904PnHtp08=; b=6ciRNwWoLRn3r8S7pMDqU7jNBdClftEQbqZgEz6w6qwGpepyTHprMrAEU2QznuXorJ ZiM4sNlQYZappFGj26IEuqqXQrIrNSkMHPbrtXHmbS9xVh9i6UpsU2k8Pc+rX/OjKmrV svIYWHGFelvqCRfvgnfChI3HBybozxDCj/bJMcFb75hCTdIl740veYnoPeFqmGunT0EO cuvGIOEfRtaX0TafZzXUNzHonUojn8PjggkAutdB2YpmLzMeEVU0L1iJzKQ6cPcVFkms I2DS8q441x+LcW5xdR28NQ6Rr/JGl5y5xvNwY3yI3DCmSWIzRzbP47aFyff/8FbT2tcw DqqQ== X-Gm-Message-State: AOAM533Ijbr/KsN9rLD6/U90iJCJ2Z7quCZBqZrFIyPcW5PeYu4qYPxs j1kr24PZrfyvtC+c7VHoE3RDoKVYpwyu7rx6Qu1lj98rhLGf47QOEzI/hmhD3T+YDCwCnBVdiEz v29iObSoBIoIF6/DKoSm8bCvTgTTUe+E= X-Received: by 2002:a05:622a:252:b0:305:2d69:edef with SMTP id c18-20020a05622a025200b003052d69edefmr7835570qtx.592.1655287395839; Wed, 15 Jun 2022 03:03:15 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxyv1mgBXRJPqyE10iMpwrbXPwzQY8+881MCTLb8+cA2QcEKQX4FjFDFFK/pm4hyVYs++rYfTscqXMUaYX8gR8= X-Received: by 2002:a05:622a:252:b0:305:2d69:edef with SMTP id c18-20020a05622a025200b003052d69edefmr7835520qtx.592.1655287395402; Wed, 15 Jun 2022 03:03:15 -0700 (PDT) MIME-Version: 1.0 References: <20220519191306.821774-1-eperezma@redhat.com> In-Reply-To: From: Eugenio Perez Martin Date: Wed, 15 Jun 2022 12:02:39 +0200 Message-ID: Subject: Re: [RFC PATCH v8 00/21] Net Control VQ support with asid in vDPA SVQ To: Jason Wang Cc: qemu-level , Gautam Dawar , "Michael S. Tsirkin" , Markus Armbruster , "Gonglei (Arei)" , Harpreet Singh Anand , Cornelia Huck , Zhu Lingshan , Laurent Vivier , Eli Cohen , Paolo Bonzini , Liuxiangdong , Eric Blake , Cindy Lu , Parav Pandit Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=170.10.133.124; envelope-from=eperezma@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, 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Jun 15, 2022 at 5:04 AM Jason Wang wrote: > > On Tue, Jun 14, 2022 at 5:32 PM Eugenio Perez Martin > wrote: > > > > On Tue, Jun 14, 2022 at 10:20 AM Jason Wang wrote= : > > > > > > On Tue, Jun 14, 2022 at 4:14 PM Eugenio Perez Martin > > > wrote: > > > > > > > > On Tue, Jun 14, 2022 at 10:02 AM Jason Wang w= rote: > > > > > > > > > > On Tue, Jun 14, 2022 at 12:32 AM Eugenio Perez Martin > > > > > wrote: > > > > > > > > > > > > On Wed, Jun 8, 2022 at 9:28 PM Eugenio Perez Martin wrote: > > > > > > > > > > > > > > On Wed, Jun 8, 2022 at 7:51 AM Jason Wang wrote: > > > > > > > > > > > > > > > > > > > > > > > > =E5=9C=A8 2022/5/20 03:12, Eugenio P=C3=A9rez =E5=86=99=E9= =81=93: > > > > > > > > > Control virtqueue is used by networking device for accept= ing various > > > > > > > > > commands from the driver. It's a must to support multique= ue and other > > > > > > > > > configurations. > > > > > > > > > > > > > > > > > > Shadow VirtQueue (SVQ) already makes possible migration o= f virtqueue > > > > > > > > > states, effectively intercepting them so qemu can track w= hat regions of memory > > > > > > > > > are dirty because device action and needs migration. Howe= ver, this does not > > > > > > > > > solve networking device state seen by the driver because = CVQ messages, like > > > > > > > > > changes on MAC addresses from the driver. > > > > > > > > > > > > > > > > > > To solve that, this series uses SVQ infraestructure propo= sed to intercept > > > > > > > > > networking control messages used by the device. This way,= qemu is able to > > > > > > > > > update VirtIONet device model and to migrate it. > > > > > > > > > > > > > > > > > > However, to intercept all queues would slow device data f= orwarding. To solve > > > > > > > > > that, only the CVQ must be intercepted all the time. This= is achieved using > > > > > > > > > the ASID infraestructure, that allows different translati= ons for different > > > > > > > > > virtqueues. The most updated kernel part of ASID is propo= sed at [1]. > > > > > > > > > > > > > > > > > > You can run qemu in two modes after applying this series:= only intercepting > > > > > > > > > cvq with x-cvq-svq=3Don or intercept all the virtqueues a= dding cmdline x-svq=3Don: > > > > > > > > > > > > > > > > > > -netdev type=3Dvhost-vdpa,vhostdev=3D/dev/vhost-vdpa-0,id= =3Dvhost-vdpa0,x-cvq-svq=3Don,x-svq=3Don > > > > > > > > > > > > > > > > > > First three patches enable the update of the virtio-net d= evice model for each > > > > > > > > > CVQ message acknoledged by the device. > > > > > > > > > > > > > > > > > > Patches from 5 to 9 enables individual SVQ to copy the bu= ffers to QEMU's VA. > > > > > > > > > This allows simplyfing the memory mapping, instead of map= all the guest's > > > > > > > > > memory like in the data virtqueues. > > > > > > > > > > > > > > > > > > Patch 10 allows to inject control messages to the device.= This allows to set > > > > > > > > > state to the device both at QEMU startup and at live migr= ation destination. In > > > > > > > > > the future, this may also be used to emulate _F_ANNOUNCE. > > > > > > > > > > > > > > > > > > Patch 11 updates kernel headers, but it assign random num= bers to needed ioctls > > > > > > > > > because they are still not accepted in the kernel. > > > > > > > > > > > > > > > > > > Patches 12-16 enables the set of the features of the net = device model to the > > > > > > > > > vdpa device at device start. > > > > > > > > > > > > > > > > > > Last ones enables the sepparated ASID and SVQ. > > > > > > > > > > > > > > > > > > Comments are welcomed. > > > > > > > > > > > > > > > > > > > > > > > > As discussed, I think we need to split this huge series int= o smaller ones: > > > > > > > > > > > > > > > > 1) shadow CVQ only, this makes rx-filter-event work > > > > > > > > 2) ASID support for CVQ > > > > > > > > > > > > > > > > And for 1) we need consider whether or not it could be simp= lified. > > > > > > > > > > > > > > > > Or do it in reverse order, since if we do 1) first, we may = have security > > > > > > > > issues. > > > > > > > > > > > > > > > > > > > > > > I'm ok with both, but I also think 2) before 1) might make mo= re sense. > > > > > > > There is no way to only shadow CVQ otherwise ATM. > > > > > > > > > > > > > > > > > > > On second thought, that order is kind of harder. > > > > > > > > > > > > If we only map CVQ buffers, we need to either: > > > > > > a. Copy them to controlled buffers > > > > > > b. Track properly when to unmap them > > > > > > > > > > Just to make sure we're at the same page: > > > > > > > > > > I meant we can start with e.g having a dedicated ASID for CVQ but > > > > > still using CVQ passthrough. > > > > > > > > > > > > > That would imply duplicating all the memory listener updates to bot= h > > > > ASIDs. That part of the code needs to be reverted. I'm ok with that= , > > > > but I'm not sure if it's worth it to do it that way. > > > > > > I don't get why it is related to memory listeners. The only change is > > > > > > 1) read the groups > > > 2) set cvq to be an independent asid > > > 3) update CVQ's IOTLB with its own ASID > > > > > > > How to track the mappings of step 3) without a copy? > > So let me try to explain, what I propose is to split the patches. So > the above could be the first part. Since we know: > > 1) CVQ is passthrough to guest right now > 2) We know CVQ will use an independent ASID > > It doesn't harm to implement those first. It's unrelated to the policy > (e.g how to shadow CVQ). > > > > > If we don't copy the buffers to qemu's IOVA, we need to track when to > > unmap CVQ buffers memory. Many CVQ buffers could be in the same page, > > so we need to refcount them (or similar solution). > > Can we use fixed mapping instead of the dynamic ones? > That implies either to implement something like a memory ring (size?), or to effectively duplicate memory listener mappings. I'm not against that, but it's something we need to remove on the final solution. To use the order presented here will avoid that. > > > > This series copies the buffers to an independent buffer in qemu memory > > to avoid that. Once you copy them, we have the problem you point at > > some patch later: The guest control buffers, so qemu must understand > > CVQ so the guest cannot trick it. All of this is orthogonal to ASID. > > At that point, we have this series except for the asid part and the > > injection of CVQ buffers at the LM destination, isn't it? > > So we have several stuffs: > > 1) ASID support > 2) Shadow CVQ only > 3) State restoring > > I hope we can split them into independent series. If we want to shadow > CVQ first, we need to prove that it is safe without ASID. > > > > > CVQ buffers can be copied in the qemu IOVA space and be offered to the > > device. Much like SVQ vrings, the copied buffers will not be > > accessible from the guest. The hw device (as "non emulated cvq") will > > receive a lot of dma updates, but it's temporary. We can add ASID on > > top of that as a mean to: > > - Not to SVQ data plane (fundamental to the intended use case of vdpa). > > - Not to pollute data plane DMA mappings. > > > > > ? > > > > > > > > > > > > Then do other stuff on top. > > > > > > > > > > > > > > > > > Alternative a. have the same problems exposed in this RFC: It's= hard > > > > > > (and unneeded in the final version) to know the size to copy. > > > > > > Alternative b. also requires things not needed in the final ver= sion, > > > > > > like to count the number of times each page is mapped and unmap= ped. > > > > > > > > > > > > So I'll go to the first alternative, that is also the proposed = order > > > > > > of the RFC. What security issues do you expect beyond the comme= nts in > > > > > > this series? > > > > > > > > > > If we shadow CVQ without ASID. The guest may guess the IOVA of CV= Q and > > > > > try to peek/modify it? > > > > > > > > > > > > > It works the same way as data vqs, we're just updating the device > > > > model in the middle. It should imply the exact same risk as updatin= g > > > > an emulated NIC control plane (including vhost-kernel / vhost-user)= . > > > > > > Not sure I got you here. For vhost-kernel and vhost-user, CVQ's buffe= r > > > is owned by guests. > > > > > > > The same way they control the data plane when all data virtqueues are > > shadowed for dirty page tracking (more on the risk of qemu updating > > the device model below). > > Ok. > > > > > > But if we shadow CVQ without ASID, the CVQ buffer is owned by QEMU an= d > > > there's no way to prevent guests from accessing it? > > > > > > > With SVQ the memory exposed to the device is already shadowed. They > > cannot access the CVQ buffers memory the same way they cannot access > > the SVQ vrings. > > Ok, I think I kind of get you, it looks like we have different > assumptions here: So if we only shadow CVQ, it will have security > issues, since RX/TX is not shadowed. If we shadow CVQ as well as > TX/RX, there's no security issue, since each IOVA is validated and the > descriptors are prepared by Qemu. > Right. I expected to maintain the all-shadowed-or-nothing behavior, sorry if I was not clear. > This goes back to another question, what's the order of the series. > I think that the shortest path is to follow the order of this series. I tried to reorder your way, but ASID patches have to come with a lot of CVQ patches if we want proper validation. We can take the long route if we either implement a fixed ring buffer, memory listener cloning, or another use case (sub-slicing?). But I expect more issues to arise there. I have another question actually, is it ok to implement the cvq use case but not to merge the x-svq parameter? The more I think on the parameter the more I see it's better to leave it as a separated patch for testing until we shape the complete series and it's unneeded. Thanks! > Thanks > > > > > > > If in the case of vhost-kernel/vhost-user, there's a way for the gues= t > > > to exploit buffers owned by Qemu, it should be a bug. > > > > > > > The only extra step is the call to virtio_net_handle_ctrl_iov > > (extracted from virtio_net_handle_ctrl). If a guest can exploit that > > in SVQ mode, it can exploit it too with other vhost backends as far as > > I see. > > > > > Thanks > > > > > > > > > > > Roughly speaking, it's just to propose patches 01 to 03, with your > > > > comments. That already meets use cases like rx filter notifications > > > > for devices with only one ASID. > > > > > > > > This part of my mail is not correct, we need to add a few patches of > > this series on top :). If not, it would be exploitable. > > > > Thanks! > > > > > > Thanks! > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > Thanks! > > > > > > > > > > > > > Can we do as with previous base SVQ patches? they were merged= although > > > > > > > there is still no way to enable SVQ. > > > > > > > > > > > > > > Thanks! > > > > > > > > > > > > > > > Thoughts? > > > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > TODO: > > > > > > > > > * Fallback on regular CVQ if QEMU cannot isolate in its o= wn ASID by any > > > > > > > > > reason, blocking migration. This is tricky, since it c= an cause that the VM > > > > > > > > > cannot be migrated anymore, so some way of block it mu= st be used. > > > > > > > > > * Review failure paths, some are with TODO notes, other d= on't. > > > > > > > > > > > > > > > > > > Changes from rfc v7: > > > > > > > > > * Don't map all guest space in ASID 1 but copy all the bu= ffers. No need for > > > > > > > > > more memory listeners. > > > > > > > > > * Move net backend start callback to SVQ. > > > > > > > > > * Wait for device CVQ commands used by the device at SVQ = start, avoiding races. > > > > > > > > > * Changed ioctls, but they're provisional anyway. > > > > > > > > > * Reorder commits so refactor and code adding ones are cl= oser to usage. > > > > > > > > > * Usual cleaning: better tracing, doc, patches messages, = ... > > > > > > > > > > > > > > > > > > Changes from rfc v6: > > > > > > > > > * Fix bad iotlb updates order when batching was enabled > > > > > > > > > * Add reference counting to iova_tree so cleaning is simp= ler. > > > > > > > > > > > > > > > > > > Changes from rfc v5: > > > > > > > > > * Fixes bad calculus of cvq end group when MQ is not acke= d by the guest. > > > > > > > > > > > > > > > > > > Changes from rfc v4: > > > > > > > > > * Add missing tracing > > > > > > > > > * Add multiqueue support > > > > > > > > > * Use already sent version for replacing g_memdup > > > > > > > > > * Care with memory management > > > > > > > > > > > > > > > > > > Changes from rfc v3: > > > > > > > > > * Fix bad returning of descriptors to SVQ list. > > > > > > > > > > > > > > > > > > Changes from rfc v2: > > > > > > > > > * Fix use-after-free. > > > > > > > > > > > > > > > > > > Changes from rfc v1: > > > > > > > > > * Rebase to latest master. > > > > > > > > > * Configure ASID instead of assuming cvq asid !=3D data v= qs asid. > > > > > > > > > * Update device model so (MAC) state can be migrated too. > > > > > > > > > > > > > > > > > > [1] https://lkml.kernel.org/kvm/20220224212314.1326-1-gda= war@xilinx.com/ > > > > > > > > > > > > > > > > > > Eugenio P=C3=A9rez (21): > > > > > > > > > virtio-net: Expose ctrl virtqueue logic > > > > > > > > > vhost: Add custom used buffer callback > > > > > > > > > vdpa: control virtqueue support on shadow virtqueue > > > > > > > > > virtio: Make virtqueue_alloc_element non-static > > > > > > > > > vhost: Add vhost_iova_tree_find > > > > > > > > > vdpa: Add map/unmap operation callback to SVQ > > > > > > > > > vhost: move descriptor translation to vhost_svq_vring_= write_descs > > > > > > > > > vhost: Add SVQElement > > > > > > > > > vhost: Add svq copy desc mode > > > > > > > > > vhost: Add vhost_svq_inject > > > > > > > > > vhost: Update kernel headers > > > > > > > > > vdpa: delay set_vring_ready after DRIVER_OK > > > > > > > > > vhost: Add ShadowVirtQueueStart operation > > > > > > > > > vhost: Make possible to check for device exclusive vq = group > > > > > > > > > vhost: add vhost_svq_poll > > > > > > > > > vdpa: Add vhost_vdpa_start_control_svq > > > > > > > > > vdpa: Add asid attribute to vdpa device > > > > > > > > > vdpa: Extract get features part from vhost_vdpa_get_ma= x_queue_pairs > > > > > > > > > vhost: Add reference counting to vhost_iova_tree > > > > > > > > > vdpa: Add x-svq to NetdevVhostVDPAOptions > > > > > > > > > vdpa: Add x-cvq-svq > > > > > > > > > > > > > > > > > > qapi/net.json | 13 +- > > > > > > > > > hw/virtio/vhost-iova-tree.h | 7 +- > > > > > > > > > hw/virtio/vhost-shadow-virtqueue.h | 61 ++- > > > > > > > > > include/hw/virtio/vhost-vdpa.h | 3 + > > > > > > > > > include/hw/virtio/vhost.h | 3 + > > > > > > > > > include/hw/virtio/virtio-net.h | 4 + > > > > > > > > > include/hw/virtio/virtio.h | 1 + > > > > > > > > > include/standard-headers/linux/vhost_types.h | 11 +- > > > > > > > > > linux-headers/linux/vhost.h | 25 +- > > > > > > > > > hw/net/vhost_net.c | 5 +- > > > > > > > > > hw/net/virtio-net.c | 84 +++-= - > > > > > > > > > hw/virtio/vhost-iova-tree.c | 35 +- > > > > > > > > > hw/virtio/vhost-shadow-virtqueue.c | 378 ++++= ++++++++++++--- > > > > > > > > > hw/virtio/vhost-vdpa.c | 206 ++++= +++++- > > > > > > > > > hw/virtio/virtio.c | 2 +- > > > > > > > > > net/vhost-vdpa.c | 294 ++++= ++++++++++- > > > > > > > > > hw/virtio/trace-events | 10 +- > > > > > > > > > 17 files changed, 1012 insertions(+), 130 deletions(-) > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >