Re: [RFC PATCH 00/22] Enhance VHOST to enable SoC-to-SoC communication

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On 2020/7/2 下午5:51, Michael S. Tsirkin wrote:
On Thu, Jul 02, 2020 at 01:51:21PM +0530, Kishon Vijay Abraham I wrote:
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@xxxxxx

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.

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).

Have you considered to implement these through vDPA?

Thanks



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%)

--
2.17.1





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