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From: "Michael S. Tsirkin" <mst@redhat.com>
To: Yongji Xie <xieyongji@bytedance.com>
Cc: "Jason Wang" <jasowang@redhat.com>,
	"Stefan Hajnoczi" <stefanha@redhat.com>,
	"Stefano Garzarella" <sgarzare@redhat.com>,
	"Parav Pandit" <parav@nvidia.com>,
	"Christoph Hellwig" <hch@infradead.org>,
	"Christian Brauner" <christian.brauner@canonical.com>,
	"Randy Dunlap" <rdunlap@infradead.org>,
	"Matthew Wilcox" <willy@infradead.org>,
	"Al Viro" <viro@zeniv.linux.org.uk>,
	"Jens Axboe" <axboe@kernel.dk>,
	bcrl@kvack.org, "Jonathan Corbet" <corbet@lwn.net>,
	"Mika Penttilä" <mika.penttila@nextfour.com>,
	"Dan Carpenter" <dan.carpenter@oracle.com>,
	joro@8bytes.org, "Greg KH" <gregkh@linuxfoundation.org>,
	"He Zhe" <zhe.he@windriver.com>,
	"Liu Xiaodong" <xiaodong.liu@intel.com>,
	"Joe Perches" <joe@perches.com>,
	"Robin Murphy" <robin.murphy@arm.com>,
	"Will Deacon" <will@kernel.org>,
	"John Garry" <john.garry@huawei.com>,
	songmuchun@bytedance.com,
	virtualization <virtualization@lists.linux-foundation.org>,
	Netdev <netdev@vger.kernel.org>, kvm <kvm@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org, iommu@lists.linux-foundation.org,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v12 00/13] Introduce VDUSE - vDPA Device in Userspace
Date: Tue, 11 Jan 2022 08:04:10 -0500	[thread overview]
Message-ID: <20220111080359-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <CACycT3sdfAbdByKJwg8N-Jb2qVDdgfSqprp_aOp5fpYz4LxmgA@mail.gmail.com>

On Tue, Jan 11, 2022 at 08:57:49PM +0800, Yongji Xie wrote:
> On Tue, Jan 11, 2022 at 7:54 PM Michael S. Tsirkin <mst@redhat.com> wrote:
> >
> > On Tue, Jan 11, 2022 at 11:31:37AM +0800, Yongji Xie wrote:
> > > On Mon, Jan 10, 2022 at 11:44 PM Michael S. Tsirkin <mst@redhat.com> wrote:
> > > >
> > > > On Mon, Jan 10, 2022 at 11:24:40PM +0800, Yongji Xie wrote:
> > > > > On Mon, Jan 10, 2022 at 11:10 PM Michael S. Tsirkin <mst@redhat.com> wrote:
> > > > > >
> > > > > > On Mon, Jan 10, 2022 at 09:54:08PM +0800, Yongji Xie wrote:
> > > > > > > On Mon, Jan 10, 2022 at 8:57 PM Michael S. Tsirkin <mst@redhat.com> wrote:
> > > > > > > >
> > > > > > > > On Mon, Aug 30, 2021 at 10:17:24PM +0800, Xie Yongji wrote:
> > > > > > > > > This series introduces a framework that makes it possible to implement
> > > > > > > > > software-emulated vDPA devices in userspace. And to make the device
> > > > > > > > > emulation more secure, the emulated vDPA device's control path is handled
> > > > > > > > > in the kernel and only the data path is implemented in the userspace.
> > > > > > > > >
> > > > > > > > > Since the emuldated vDPA device's control path is handled in the kernel,
> > > > > > > > > a message mechnism is introduced to make userspace be aware of the data
> > > > > > > > > path related changes. Userspace can use read()/write() to receive/reply
> > > > > > > > > the control messages.
> > > > > > > > >
> > > > > > > > > In the data path, the core is mapping dma buffer into VDUSE daemon's
> > > > > > > > > address space, which can be implemented in different ways depending on
> > > > > > > > > the vdpa bus to which the vDPA device is attached.
> > > > > > > > >
> > > > > > > > > In virtio-vdpa case, we implements a MMU-based software IOTLB with
> > > > > > > > > bounce-buffering mechanism to achieve that. And in vhost-vdpa case, the dma
> > > > > > > > > buffer is reside in a userspace memory region which can be shared to the
> > > > > > > > > VDUSE userspace processs via transferring the shmfd.
> > > > > > > > >
> > > > > > > > > The details and our user case is shown below:
> > > > > > > > >
> > > > > > > > > ------------------------    -------------------------   ----------------------------------------------
> > > > > > > > > |            Container |    |              QEMU(VM) |   |                               VDUSE daemon |
> > > > > > > > > |       ---------      |    |  -------------------  |   | ------------------------- ---------------- |
> > > > > > > > > |       |dev/vdx|      |    |  |/dev/vhost-vdpa-x|  |   | | vDPA device emulation | | block driver | |
> > > > > > > > > ------------+-----------     -----------+------------   -------------+----------------------+---------
> > > > > > > > >             |                           |                            |                      |
> > > > > > > > >             |                           |                            |                      |
> > > > > > > > > ------------+---------------------------+----------------------------+----------------------+---------
> > > > > > > > > |    | block device |           |  vhost device |            | vduse driver |          | TCP/IP |    |
> > > > > > > > > |    -------+--------           --------+--------            -------+--------          -----+----    |
> > > > > > > > > |           |                           |                           |                       |        |
> > > > > > > > > | ----------+----------       ----------+-----------         -------+-------                |        |
> > > > > > > > > | | virtio-blk driver |       |  vhost-vdpa driver |         | vdpa device |                |        |
> > > > > > > > > | ----------+----------       ----------+-----------         -------+-------                |        |
> > > > > > > > > |           |      virtio bus           |                           |                       |        |
> > > > > > > > > |   --------+----+-----------           |                           |                       |        |
> > > > > > > > > |                |                      |                           |                       |        |
> > > > > > > > > |      ----------+----------            |                           |                       |        |
> > > > > > > > > |      | virtio-blk device |            |                           |                       |        |
> > > > > > > > > |      ----------+----------            |                           |                       |        |
> > > > > > > > > |                |                      |                           |                       |        |
> > > > > > > > > |     -----------+-----------           |                           |                       |        |
> > > > > > > > > |     |  virtio-vdpa driver |           |                           |                       |        |
> > > > > > > > > |     -----------+-----------           |                           |                       |        |
> > > > > > > > > |                |                      |                           |    vdpa bus           |        |
> > > > > > > > > |     -----------+----------------------+---------------------------+------------           |        |
> > > > > > > > > |                                                                                        ---+---     |
> > > > > > > > > -----------------------------------------------------------------------------------------| NIC |------
> > > > > > > > >                                                                                          ---+---
> > > > > > > > >                                                                                             |
> > > > > > > > >                                                                                    ---------+---------
> > > > > > > > >                                                                                    | Remote Storages |
> > > > > > > > >                                                                                    -------------------
> > > > > > > > >
> > > > > > > > > We make use of it to implement a block device connecting to
> > > > > > > > > our distributed storage, which can be used both in containers and
> > > > > > > > > VMs. Thus, we can have an unified technology stack in this two cases.
> > > > > > > > >
> > > > > > > > > To test it with null-blk:
> > > > > > > > >
> > > > > > > > >   $ qemu-storage-daemon \
> > > > > > > > >       --chardev socket,id=charmonitor,path=/tmp/qmp.sock,server,nowait \
> > > > > > > > >       --monitor chardev=charmonitor \
> > > > > > > > >       --blockdev driver=host_device,cache.direct=on,aio=native,filename=/dev/nullb0,node-name=disk0 \
> > > > > > > > >       --export type=vduse-blk,id=test,node-name=disk0,writable=on,name=vduse-null,num-queues=16,queue-size=128
> > > > > > > > >
> > > > > > > > > The qemu-storage-daemon can be found at https://github.com/bytedance/qemu/tree/vduse
> > > > > > > >
> > > > > > > > It's been half a year - any plans to upstream this?
> > > > > > >
> > > > > > > Yeah, this is on my to-do list this month.
> > > > > > >
> > > > > > > Sorry for taking so long... I've been working on another project
> > > > > > > enabling userspace RDMA with VDUSE for the past few months. So I
> > > > > > > didn't have much time for this. Anyway, I will submit the first
> > > > > > > version as soon as possible.
> > > > > > >
> > > > > > > Thanks,
> > > > > > > Yongji
> > > > > >
> > > > > > Oh fun. You mean like virtio-rdma? Or RDMA as a backend for regular
> > > > > > virtio?
> > > > > >
> > > > >
> > > > > Yes, like virtio-rdma. Then we can develop something like userspace
> > > > > rxe、siw or custom protocol with VDUSE.
> > > > >
> > > > > Thanks,
> > > > > Yongji
> > > >
> > > > Would be interesting to see the spec for that.
> > >
> > > Will send it ASAP.
> > >
> > > > The issues with RDMA revolved around the fact that current
> > > > apps tend to either use non-standard propocols for connection
> > > > establishment or use UD where there's IIRC no standard
> > > > at all. So QP numbers are hard to virtualize.
> > > > Similarly many use LIDs directly with the same effect.
> > > > GUIDs might be virtualizeable but no one went to the effort.
> > > >
> > >
> > > Actually we aimed at emulating a soft RDMA with normal NIC (not use
> > > RDMA capability) rather than virtualizing a physical RDMA NIC into
> > > several vRDMA devices. If so, I think we won't have those issues,
> > > right?
> >
> > Right, maybe you won't.
> >
> > > > To say nothing about the interaction with memory overcommit.
> > > >
> > >
> > > I don't get you here. Could you give me more details?
> > >
> > > Thanks,
> > > Yongji
> >
> > RDMA devices tend to want to pin the memory under DMA.
> >
> 
> I see. Maybe something like dm or odp could be helpful.
> 
> Thanks,
> Yongji

Yes sure.

-- 
MST


      reply	other threads:[~2022-01-11 13:04 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-30 14:17 Xie Yongji
2021-08-30 14:17 ` [PATCH v12 01/13] iova: Export alloc_iova_fast() and free_iova_fast() Xie Yongji
2021-08-30 14:17 ` [PATCH v12 02/13] eventfd: Export eventfd_wake_count to modules Xie Yongji
2021-08-30 14:17 ` [PATCH v12 03/13] file: Export receive_fd() " Xie Yongji
2021-08-30 14:17 ` [PATCH v12 04/13] vdpa: Fix some coding style issues Xie Yongji
2021-08-30 14:17 ` [PATCH v12 05/13] vdpa: Add reset callback in vdpa_config_ops Xie Yongji
2021-09-06  5:54   ` Michael S. Tsirkin
2021-08-30 14:17 ` [PATCH v12 06/13] vhost-vdpa: Handle the failure of vdpa_reset() Xie Yongji
2021-08-30 14:17 ` [PATCH v12 07/13] vhost-iotlb: Add an opaque pointer for vhost IOTLB Xie Yongji
2021-08-30 14:17 ` [PATCH v12 08/13] vdpa: Add an opaque pointer for vdpa_config_ops.dma_map() Xie Yongji
2021-08-30 14:17 ` [PATCH v12 09/13] vdpa: factor out vhost_vdpa_pa_map() and vhost_vdpa_pa_unmap() Xie Yongji
2021-08-30 14:17 ` [PATCH v12 10/13] vdpa: Support transferring virtual addressing during DMA mapping Xie Yongji
2021-08-30 14:17 ` [PATCH v12 11/13] vduse: Implement an MMU-based software IOTLB Xie Yongji
2021-08-30 14:17 ` [PATCH v12 12/13] vduse: Introduce VDUSE - vDPA Device in Userspace Xie Yongji
2021-08-30 14:17 ` [PATCH v12 13/13] Documentation: Add documentation for VDUSE Xie Yongji
2022-01-10 12:56 ` [PATCH v12 00/13] Introduce VDUSE - vDPA Device in Userspace Michael S. Tsirkin
2022-01-10 13:54   ` Yongji Xie
2022-01-10 15:09     ` Michael S. Tsirkin
2022-01-10 15:24       ` Yongji Xie
2022-01-10 15:44         ` Michael S. Tsirkin
2022-01-11  3:31           ` Yongji Xie
2022-01-11 11:54             ` Michael S. Tsirkin
2022-01-11 12:57               ` Yongji Xie
2022-01-11 13:04                 ` Michael S. Tsirkin [this message]

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