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SubjectRe: [EXT] [RFC PATCH 0/3] Introduce a PCIe endpoint virtio console
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On 2023/04/14 23:39, Frank Li wrote:
>
>> -----Original Message-----
>> From: Shunsuke Mie <mie@igel.co.jp>
>> Sent: Friday, April 14, 2023 7:39 AM
>> To: Lorenzo Pieralisi <lpieralisi@kernel.org>
>> Cc: Krzysztof Wilczyński <kw@linux.com>; Manivannan Sadhasivam
>> <mani@kernel.org>; Kishon Vijay Abraham I <kishon@kernel.org>; Bjorn
>> Helgaas <bhelgaas@google.com>; Michael S. Tsirkin <mst@redhat.com>;
>> Jason Wang <jasowang@redhat.com>; Shunsuke Mie <mie@igel.co.jp>;
>> Frank Li <frank.li@nxp.com>; Jon Mason <jdmason@kudzu.us>; Randy
>> Dunlap <rdunlap@infradead.org>; Ren Zhijie <renzhijie2@huawei.com>;
>> linux-kernel@vger.kernel.org; linux-pci@vger.kernel.org;
>> virtualization@lists.linux-foundation.org
>> 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?

I'm sorry I didn't understand your question. What do you mean the
virtiobus directly?

>
> Previous you use virtio-net, why change to virtio-console here? Does it matter?

No, it doesn't. Just I'd like to break down the changes into smaller
steps to make it easier to review and merge the changes.

As a first step, I propose adding a simplest virtio function driver with
the extension defined in pci-epf-virtio.{h,c}.

> All virtio-XXX should work?
Yes, the extension is designed to use any type of virtio device.
>
> You removed EDMA support this version?
I planed the support will be added with epf virtio-net patches.
>
>> 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

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