RE: [EXT] [RFC PATCH 0/3] Introduce a PCIe endpoint virtio console

[Frank Li]

> -----Original Message-----
> From: Shunsuke Mie <mie@xxxxxxxxxx>
> Sent: Friday, April 14, 2023 7:39 AM
> To: Lorenzo Pieralisi <lpieralisi@xxxxxxxxxx>
> Cc: Krzysztof Wilczyński <kw@xxxxxxxxx>; Manivannan Sadhasivam
> <mani@xxxxxxxxxx>; Kishon Vijay Abraham I <kishon@xxxxxxxxxx>; Bjorn
> Helgaas <bhelgaas@xxxxxxxxxx>; Michael S. Tsirkin <mst@xxxxxxxxxx>;
> Jason Wang <jasowang@xxxxxxxxxx>; Shunsuke Mie <mie@xxxxxxxxxx>;
> Frank Li <frank.li@xxxxxxx>; Jon Mason <jdmason@xxxxxxxx>; Randy
> Dunlap <rdunlap@xxxxxxxxxxxxx>; Ren Zhijie <renzhijie2@xxxxxxxxxx>;
> linux-kernel@xxxxxxxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx;
> virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
> Subject: [EXT] [RFC PATCH 0/3] Introduce a PCIe endpoint virtio console
>
> Caution: EXT Email
>
> PCIe endpoint framework provides APIs to implement PCIe endpoint
> function.
> This framework allows defining various PCIe endpoint function behaviors in
> software. This patch extend the framework for virtio pci device. The
> virtio is defined to communicate guest on virtual machine and host side.
> Advantage of the virtio is the efficiency of data transfer and the conciseness
> of implementation device using software. It also be applied to PCIe
> endpoint function.
>
> We designed and implemented a PCIe EP virtio console function driver using
> the extended PCIe endpoint framework for virtio. It can be communicate
> host and endpoint over virtio as console.
>
> An architecture of the function driver is following:
>
>  ┌────────────┐         ┌──────────────
> ────────┬────────────┐
>  │virtio      │         │                      │virtio      │
>  │console drv │         ├───────────────┐      │console
> drv │
>  ├────────────┤         │(virtio console│      ├─────
> ───────┤
>  │ virtio bus │         │ device)       │◄────►│ virtio bus │
>  ├────────────┤         ├---------------┤      └──────
> ──────┤
>  │            │         │ pci ep virtio │                   │
>  │  pci bus   │         │  console drv  │                   │
>  │            │  pcie   ├───────────────┤                   │
>  │            │ ◄─────► │  pci ep Bus   │                   │
>  └────────────┘         └──────────────
> ─┴───────────────────┘
>    PCIe Root              PCIe Endpoint
>

[Frank Li] Some basic question,
I see you call register_virtio_device at epf_vcon_setup_vdev,
Why call it as virtio console?  I suppose it should be virtiobus directly?

Previous you use virtio-net, why change to virtio-console here?  Does it matter?
All virtio-XXX should work?

You removed EDMA support this version?


> Introduced driver is `pci ep virtio console drv` in the figure. It works
> as ep function for PCIe root and virtual virtio console device for PCIe
> endpoint. Each side of virtio console driver has virtqueue, and
> introduced driver transfers data on the virtqueue to each other. A data
> on root tx queue is transfered to endpoint rx queue and vice versa.
>
> This patchset is depend follwing patches which are under discussion.
>
> - [RFC PATCH 0/3] Deal with alignment restriction on EP side
> link:
> https://lore.k/
> ernel.org%2Flinux-pci%2F20230113090350.1103494-1-
> mie%40igel.co.jp%2F&data=05%7C01%7CFrank.Li%40nxp.com%7Cea6513dbf
> 4084b80ced208db3ce54133%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7
> C0%7C638170727558800720%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4w
> LjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C
> %7C%7C&sdata=jYgy%2Bxk84ZXZRVfqm0GCXoRnCTLMrX4zTfV%2Bs5Mmsvo
> %3D&reserved=0
> - [RFC PATCH v2 0/7] Introduce a vringh accessor for IO memory
> link:
> https://lore.k/
> ernel.org%2Fvirtualization%2F20230202090934.549556-1-
> mie%40igel.co.jp%2F&data=05%7C01%7CFrank.Li%40nxp.com%7Cea6513dbf
> 4084b80ced208db3ce54133%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7
> C0%7C638170727558800720%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4w
> LjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C
> %7C%7C&sdata=K4El76GSAGtsWkNBXJK5%2Fn7flCN20eEMZpZYTX2WIZ0%3
> D&reserved=0
>
> First of this patchset is introduce a helper function to realize pci
> virtio function using PCIe endpoint framework. The second one is adding
> a missing definition for virtio pci header. The last one is for PCIe
> endpoint virtio console driver.
>
> This is tested on linux-20230406 and RCar S4 board as PCIe endpoint.
>
> Shunsuke Mie (3):
>   PCI: endpoint: introduce a helper to implement pci ep virtio function
>   virtio_pci: add a definition of queue flag in ISR
>   PCI: endpoint: Add EP function driver to provide virtio-console
>     functionality
>
>  drivers/pci/endpoint/functions/Kconfig        |  19 +
>  drivers/pci/endpoint/functions/Makefile       |   2 +
>  drivers/pci/endpoint/functions/pci-epf-vcon.c | 554 ++++++++++++++++++
>  .../pci/endpoint/functions/pci-epf-virtio.c   | 469 +++++++++++++++
>  .../pci/endpoint/functions/pci-epf-virtio.h   | 123 ++++
>  include/uapi/linux/virtio_pci.h               |   3 +
>  6 files changed, 1170 insertions(+)
>  create mode 100644 drivers/pci/endpoint/functions/pci-epf-vcon.c
>  create mode 100644 drivers/pci/endpoint/functions/pci-epf-virtio.c
>  create mode 100644 drivers/pci/endpoint/functions/pci-epf-virtio.h
>
> --
> 2.25.1