On 2020/7/2 下午9:35, Kishon Vijay Abraham I wrote:

Hi Jason,

On 7/2/2020 3:40 PM, Jason Wang wrote:

quoted

On 2020/7/2 下午5:51, Michael S. Tsirkin wrote:

quoted

On Thu, Jul 02, 2020 at 01:51:21PM +0530, Kishon Vijay Abraham I wrote:

quoted

This series enhances Linux Vhost support to enable SoC-to-SoC
communication over MMIO. This series enables rpmsg communication between
two SoCs using both PCIe RC<->EP and HOST1-NTB-HOST2

1) Modify vhost to use standard Linux driver model
2) Add support in vring to access virtqueue over MMIO
3) Add vhost client driver for rpmsg
4) Add PCIe RC driver (uses virtio) and PCIe EP driver (uses vhost) for
     rpmsg communication between two SoCs connected to each other
5) Add NTB Virtio driver and NTB Vhost driver for rpmsg communication
     between two SoCs connected via NTB
6) Add configfs to configure the components

UseCase1 :

   VHOST RPMSG                     VIRTIO RPMSG
        +                               +
        |                               |
        |                               |
        |                               |
        |                               |
+-----v------+                 +------v-------+
|   Linux    |                 |     Linux    |
|  Endpoint  |                 | Root Complex |
|            <----------------->              |
|            |                 |              |
|    SOC1    |                 |     SOC2     |
+------------+                 +--------------+

UseCase 2:

       VHOST RPMSG                                      VIRTIO RPMSG
            +                                                 +
            |                                                 |
            |                                                 |
            |                                                 |
            |                                                 |
     +------v------+                                   +------v------+
     |             |                                   |             |
     |    HOST1    |                                   |    HOST2    |
     |             |                                   |             |
     +------^------+                                   +------^------+
            |                                                 |
            |                                                 |
+---------------------------------------------------------------------+
|  +------v------+                                   +------v------+  |
|  |             |                                   |             |  |
|  |     EP      |                                   |     EP      |  |
|  | CONTROLLER1 |                                   | CONTROLLER2 |  |
|  |             <----------------------------------->             |  |
|  |             |                                   |             |  |
|  |             |                                   |             |  |
|  |             |  SoC With Multiple EP Instances   |             |  |
|  |             |  (Configured using NTB Function)  |             |  |
|  +-------------+                                   +-------------+  |
+---------------------------------------------------------------------+

Software Layering:

The high-level SW layering should look something like below. This series
adds support only for RPMSG VHOST, however something similar should be
done for net and scsi. With that any vhost device (PCI, NTB, Platform
device, user) can use any of the vhost client driver.


      +----------------+  +-----------+  +------------+  +----------+
      |  RPMSG VHOST   |  | NET VHOST |  | SCSI VHOST |  |    X     |
      +-------^--------+  +-----^-----+  +-----^------+  +----^-----+
              |                 |              |              |
              |                 |              |              |
              |                 |              |              |
+-----------v-----------------v--------------v--------------v----------+
|                            VHOST CORE                                |
+--------^---------------^--------------------^------------------^-----+
           |               |                    |                  |
           |               |                    |                  |
           |               |                    |                  |
+--------v-------+  +----v------+  +----------v----------+  +----v-----+
|  PCI EPF VHOST |  | NTB VHOST |  |PLATFORM DEVICE VHOST|  |    X     |
+----------------+  +-----------+  +---------------------+  +----------+

This was initially proposed here [1]

[1] -> https://lore.kernel.org/r/2cf00ec4-1ed6-f66e-6897-006d1a5b6390@ti.com (local)

I find this very interesting. A huge patchset so will take a bit
to review, but I certainly plan to do that. Thanks!

Yes, it would be better if there's a git branch for us to have a look.

I've pushed the branch
https://github.com/kishon/linux-wip.git vhost_rpmsg_pci_ntb_rfc

Thanks

quoted

Btw, I'm not sure I get the big picture, but I vaguely feel some of the work is
duplicated with vDPA (e.g the epf transport or vhost bus).

This is about connecting two different HW systems both running Linux and
doesn't necessarily involve virtualization.

Right, this is something similar to VOP 
(Documentation/misc-devices/mic/mic_overview.rst). The different is the 
hardware I guess and VOP use userspace application to implement the device.

  So there is no guest or host as in
virtualization but two entirely different systems connected via PCIe cable, one
acting as guest and one as host. So one system will provide virtio
functionality reserving memory for virtqueues and the other provides vhost
functionality providing a way to access the virtqueues in virtio memory. One is
source and the other is sink and there is no intermediate entity. (vhost was
probably intermediate entity in virtualization?)

(Not a native English speaker) but "vhost" could introduce some 
confusion for me since it was use for implementing virtio backend for 
userspace drivers. I guess "vringh" could be better.

quoted

Have you considered to implement these through vDPA?

IIUC vDPA only provides an interface to userspace and an in-kernel rpmsg driver
or vhost net driver is not provided.

The HW connection looks something like https://pasteboard.co/JfMVVHC.jpg
(usecase2 above),

I see.

  all the boards run Linux. The middle board provides NTB
functionality and board on either side provides virtio/vhost functionality and
transfer data using rpmsg.

So I wonder whether it's worthwhile for a new bus. Can we use the 
existed virtio-bus/drivers? It might work as, except for the epf 
transport, we can introduce a epf "vhost" transport driver.

It will have virtqueues but only used for the communication between 
itself and uppter virtio driver. And it will have vringh queues which 
will be probe by virtio epf transport drivers. And it needs to do 
datacopy between virtqueue and vringh queues.

It works like:

virtio drivers <- virtqueue/virtio-bus -> epf vhost drivers <- vringh 
queue/epf>

The advantages is that there's no need for writing new buses and drivers.

Does this make sense?

Thanks

Thanks
Kishon

quoted

Thanks

quoted

quoted

Kishon Vijay Abraham I (22):
    vhost: Make _feature_ bits a property of vhost device
    vhost: Introduce standard Linux driver model in VHOST
    vhost: Add ops for the VHOST driver to configure VHOST device
    vringh: Add helpers to access vring in MMIO
    vhost: Add MMIO helpers for operations on vhost virtqueue
    vhost: Introduce configfs entry for configuring VHOST
    virtio_pci: Use request_threaded_irq() instead of request_irq()
    rpmsg: virtio_rpmsg_bus: Disable receive virtqueue callback when
      reading messages
    rpmsg: Introduce configfs entry for configuring rpmsg
    rpmsg: virtio_rpmsg_bus: Add Address Service Notification support
    rpmsg: virtio_rpmsg_bus: Move generic rpmsg structure to
      rpmsg_internal.h
    virtio: Add ops to allocate and free buffer
    rpmsg: virtio_rpmsg_bus: Use virtio_alloc_buffer() and
      virtio_free_buffer()
    rpmsg: Add VHOST based remote processor messaging bus
    samples/rpmsg: Setup delayed work to send message
    samples/rpmsg: Wait for address to be bound to rpdev for sending
      message
    rpmsg.txt: Add Documentation to configure rpmsg using configfs
    virtio_pci: Add VIRTIO driver for VHOST on Configurable PCIe Endpoint
      device
    PCI: endpoint: Add EP function driver to provide VHOST interface
    NTB: Add a new NTB client driver to implement VIRTIO functionality
    NTB: Add a new NTB client driver to implement VHOST functionality
    NTB: Describe the ntb_virtio and ntb_vhost client in the documentation

   Documentation/driver-api/ntb.rst              |   11 +
   Documentation/rpmsg.txt                       |   56 +
   drivers/ntb/Kconfig                           |   18 +
   drivers/ntb/Makefile                          |    2 +
   drivers/ntb/ntb_vhost.c                       |  776 +++++++++++
   drivers/ntb/ntb_virtio.c                      |  853 ++++++++++++
   drivers/ntb/ntb_virtio.h                      |   56 +
   drivers/pci/endpoint/functions/Kconfig        |   11 +
   drivers/pci/endpoint/functions/Makefile       |    1 +
   .../pci/endpoint/functions/pci-epf-vhost.c    | 1144 ++++++++++++++++
   drivers/rpmsg/Kconfig                         |   10 +
   drivers/rpmsg/Makefile                        |    3 +-
   drivers/rpmsg/rpmsg_cfs.c                     |  394 ++++++
   drivers/rpmsg/rpmsg_core.c                    |    7 +
   drivers/rpmsg/rpmsg_internal.h                |  136 ++
   drivers/rpmsg/vhost_rpmsg_bus.c               | 1151 +++++++++++++++++
   drivers/rpmsg/virtio_rpmsg_bus.c              |  184 ++-
   drivers/vhost/Kconfig                         |    1 +
   drivers/vhost/Makefile                        |    2 +-
   drivers/vhost/net.c                           |   10 +-
   drivers/vhost/scsi.c                          |   24 +-
   drivers/vhost/test.c                          |   17 +-
   drivers/vhost/vdpa.c                          |    2 +-
   drivers/vhost/vhost.c                         |  730 ++++++++++-
   drivers/vhost/vhost_cfs.c                     |  341 +++++
   drivers/vhost/vringh.c                        |  332 +++++
   drivers/vhost/vsock.c                         |   20 +-
   drivers/virtio/Kconfig                        |    9 +
   drivers/virtio/Makefile                       |    1 +
   drivers/virtio/virtio_pci_common.c            |   25 +-
   drivers/virtio/virtio_pci_epf.c               |  670 ++++++++++
   include/linux/mod_devicetable.h               |    6 +
   include/linux/rpmsg.h                         |    6 +
   {drivers/vhost => include/linux}/vhost.h      |  132 +-
   include/linux/virtio.h                        |    3 +
   include/linux/virtio_config.h                 |   42 +
   include/linux/vringh.h                        |   46 +
   samples/rpmsg/rpmsg_client_sample.c           |   32 +-
   tools/virtio/virtio_test.c                    |    2 +-
   39 files changed, 7083 insertions(+), 183 deletions(-)
   create mode 100644 drivers/ntb/ntb_vhost.c
   create mode 100644 drivers/ntb/ntb_virtio.c
   create mode 100644 drivers/ntb/ntb_virtio.h
   create mode 100644 drivers/pci/endpoint/functions/pci-epf-vhost.c
   create mode 100644 drivers/rpmsg/rpmsg_cfs.c
   create mode 100644 drivers/rpmsg/vhost_rpmsg_bus.c
   create mode 100644 drivers/vhost/vhost_cfs.c
   create mode 100644 drivers/virtio/virtio_pci_epf.c
   rename {drivers/vhost => include/linux}/vhost.h (66%)

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2.17.1