From: Jason Wang <jasowang@redhat.com>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: mst <mst@redhat.com>, linux-kernel <linux-kernel@vger.kernel.org>,
kvm <kvm@vger.kernel.org>,
virtualization <virtualization@lists.linux-foundation.org>,
netdev <netdev@vger.kernel.org>,
Maxime Coquelin <maxime.coquelin@redhat.com>,
"Liang, Cunming" <cunming.liang@intel.com>,
zhihong.wang@intel.com, rob.miller@broadcom.com,
Xiao W Wang <xiao.w.wang@intel.com>,
Zhu Lingshan <lingshan.zhu@intel.com>,
eperezma <eperezma@redhat.com>, Cindy Lu <lulu@redhat.com>,
Parav Pandit <parav@mellanox.com>,
"Tian, Kevin" <kevin.tian@intel.com>,
Stefan Hajnoczi <stefanha@redhat.com>,
Randy Dunlap <rdunlap@infradead.org>,
Christoph Hellwig <hch@infradead.org>,
Ariel Adam <aadam@redhat.com>,
jiri@mellanox.com, shahafs@mellanox.com,
Harpreet Singh Anand <hanand@xilinx.com>,
mhabets@solarflare.com, Gautam Dawar <gdawar@xilinx.com>,
Saugat Mitra <saugatm@xilinx.com>,
vmireyno@marvell.com, zhangweining@ruijie.com.cn,
Tiwei Bie <tiwei.bie@intel.com>,
Lu Baolu <baolu.lu@linux.intel.com>
Subject: Re: [PATCH V9 7/9] vhost: introduce vDPA-based backend
Date: Tue, 2 Nov 2021 11:52:20 +0800 [thread overview]
Message-ID: <CACGkMEtbs3u7J7krpkusfqczTU00+6o_YtZjD8htC=+Un9cNew@mail.gmail.com> (raw)
In-Reply-To: <20211101141133.GA1073864@nvidia.com>
On Mon, Nov 1, 2021 at 10:11 PM Jason Gunthorpe <jgg@nvidia.com> wrote:
>
> On Thu, Mar 26, 2020 at 10:01:23PM +0800, Jason Wang wrote:
> > From: Tiwei Bie <tiwei.bie@intel.com>
> >
> > This patch introduces a vDPA-based vhost backend. This backend is
> > built on top of the same interface defined in virtio-vDPA and provides
> > a generic vhost interface for userspace to accelerate the virtio
> > devices in guest.
> >
> > This backend is implemented as a vDPA device driver on top of the same
> > ops used in virtio-vDPA. It will create char device entry named
> > vhost-vdpa-$index for userspace to use. Userspace can use vhost ioctls
> > on top of this char device to setup the backend.
> >
> > Vhost ioctls are extended to make it type agnostic and behave like a
> > virtio device, this help to eliminate type specific API like what
> > vhost_net/scsi/vsock did:
> >
> > - VHOST_VDPA_GET_DEVICE_ID: get the virtio device ID which is defined
> > by virtio specification to differ from different type of devices
> > - VHOST_VDPA_GET_VRING_NUM: get the maximum size of virtqueue
> > supported by the vDPA device
> > - VHSOT_VDPA_SET/GET_STATUS: set and get virtio status of vDPA device
> > - VHOST_VDPA_SET/GET_CONFIG: access virtio config space
> > - VHOST_VDPA_SET_VRING_ENABLE: enable a specific virtqueue
> >
> > For memory mapping, IOTLB API is mandated for vhost-vDPA which means
> > userspace drivers are required to use
> > VHOST_IOTLB_UPDATE/VHOST_IOTLB_INVALIDATE to add or remove mapping for
> > a specific userspace memory region.
> >
> > The vhost-vDPA API is designed to be type agnostic, but it allows net
> > device only in current stage. Due to the lacking of control virtqueue
> > support, some features were filter out by vhost-vdpa.
> >
> > We will enable more features and devices in the near future.
>
> [..]
>
> > +static int vhost_vdpa_alloc_domain(struct vhost_vdpa *v)
> > +{
> > + struct vdpa_device *vdpa = v->vdpa;
> > + const struct vdpa_config_ops *ops = vdpa->config;
> > + struct device *dma_dev = vdpa_get_dma_dev(vdpa);
> > + struct bus_type *bus;
> > + int ret;
> > +
> > + /* Device want to do DMA by itself */
> > + if (ops->set_map || ops->dma_map)
> > + return 0;
> > +
> > + bus = dma_dev->bus;
> > + if (!bus)
> > + return -EFAULT;
> > +
> > + if (!iommu_capable(bus, IOMMU_CAP_CACHE_COHERENCY))
> > + return -ENOTSUPP;
> > +
> > + v->domain = iommu_domain_alloc(bus);
> > + if (!v->domain)
> > + return -EIO;
> > +
> > + ret = iommu_attach_device(v->domain, dma_dev);
> > + if (ret)
> > + goto err_attach;
> >
>
> I've been looking at the security of iommu_attach_device() users, and
> I wonder if this is safe?
>
> The security question is if userspace is able to control the DMA
> address the devices uses? Eg if any of the cpu to device ring's are in
> userspace memory?
>
> For instance if userspace can tell the device to send a packet from an
> arbitrary user controlled address.
The map is validated via pin_user_pages() which guarantees that the
address is not arbitrary and must belong to userspace?
Thanks
>
> Thanks,
> Jason
>
next prev parent reply other threads:[~2021-11-02 3:52 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-26 14:01 [PATCH V9 0/9] vDPA support Jason Wang
2020-03-26 14:01 ` [PATCH V9 1/9] vhost: refine vhost and vringh kconfig Jason Wang
2020-04-01 11:21 ` Christian Borntraeger
2020-04-01 12:50 ` Jason Wang
2020-04-01 12:56 ` Christian Borntraeger
2020-04-01 13:02 ` Christian Borntraeger
2020-04-01 14:01 ` Michael S. Tsirkin
2020-04-01 14:13 ` Jason Wang
2020-04-01 14:18 ` Michael S. Tsirkin
2020-04-01 14:36 ` Jason Wang
2020-04-01 14:27 ` Michael S. Tsirkin
2020-04-01 14:50 ` Jason Wang
2020-04-01 15:57 ` Michael S. Tsirkin
2020-04-01 18:53 ` Christian Borntraeger
2020-04-01 13:22 ` Michael S. Tsirkin
2020-04-01 14:08 ` Jason Wang
2020-04-01 14:13 ` Michael S. Tsirkin
2020-04-01 14:29 ` Jason Wang
2020-04-01 14:35 ` Michael S. Tsirkin
2020-04-01 14:39 ` Jason Wang
2020-04-01 14:39 ` Michael S. Tsirkin
2020-04-01 14:43 ` Jason Wang
2020-04-01 16:05 ` Michael S. Tsirkin
2020-04-01 16:08 ` Michael S. Tsirkin
2020-04-02 3:22 ` Jason Wang
2020-04-02 14:03 ` Michael S. Tsirkin
2020-04-02 14:23 ` Jason Wang
2020-04-02 14:38 ` Michael S. Tsirkin
2020-04-02 14:56 ` Jason Wang
2020-03-26 14:01 ` [PATCH V9 2/9] vhost: allow per device message handler Jason Wang
2020-03-26 14:01 ` [PATCH V9 3/9] vhost: factor out IOTLB Jason Wang
2020-03-26 14:01 ` [PATCH V9 4/9] vringh: IOTLB support Jason Wang
2020-03-26 14:01 ` [PATCH V9 5/9] vDPA: introduce vDPA bus Jason Wang
2020-03-26 14:01 ` [PATCH V9 6/9] virtio: introduce a vDPA based transport Jason Wang
2020-03-26 14:01 ` [PATCH V9 7/9] vhost: introduce vDPA-based backend Jason Wang
2021-11-01 14:11 ` Jason Gunthorpe
2021-11-02 3:52 ` Jason Wang [this message]
2021-11-02 15:56 ` Jason Gunthorpe
2021-11-03 7:34 ` Jason Wang
2020-03-26 14:01 ` [PATCH V9 8/9] vdpasim: vDPA device simulator Jason Wang
2020-04-10 7:45 ` Geert Uytterhoeven
2020-04-10 8:23 ` Jason Wang
2020-03-26 14:01 ` [PATCH V9 9/9] virtio: Intel IFC VF driver for VDPA Jason Wang
2020-04-09 10:41 ` Arnd Bergmann
2020-04-09 12:43 ` Jason Wang
2020-04-09 12:49 ` Zhu, Lingshan
2020-04-09 20:25 ` Michael S. Tsirkin
2020-04-10 3:15 ` Zhu, Lingshan
2020-03-29 11:07 ` [PATCH V9 0/9] vDPA support Michael S. Tsirkin
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