Date:   Sun, 5 Feb 2023 05:01:59 -0500
From:   "Michael S. Tsirkin" <mst@redhat.com>
To:     Shunsuke Mie <mie@igel.co.jp>
Cc:     Lorenzo Pieralisi <lpieralisi@kernel.org>,
        Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= <kw@linux.com>,
        Manivannan Sadhasivam <mani@kernel.org>,
        Kishon Vijay Abraham I <kishon@kernel.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Jason Wang <jasowang@redhat.com>, Frank Li <Frank.Li@nxp.com>,
        Jon Mason <jdmason@kudzu.us>,
        Ren Zhijie <renzhijie2@huawei.com>,
        Takanari Hayama <taki@igel.co.jp>,
        linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
        virtualization@lists.linux-foundation.org
Subject: Re: [RFC PATCH 0/4] PCI: endpoint: Introduce a virtio-net EP function
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References: <20230203100418.2981144-1-mie@igel.co.jp>
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On Fri, Feb 03, 2023 at 07:04:14PM +0900, Shunsuke Mie wrote:
> This patchset introduce a virtio-net EP device function. It provides a
> new option to communiate between PCIe host and endpoint over IP.
> Advantage of this option is that the driver fully uses a PCIe embedded DMA.
> It is used to transport data between virtio ring directly each other. It
> can be expected to better throughput.
> 
> To realize the function, this patchset has few changes and introduces a
> new APIs to PCI EP framework related to virtio. Furthermore, it device
> depends on the some patchtes that is discussing. Those depended patchset
> are following:
> - [PATCH 1/2] dmaengine: dw-edma: Fix to change for continuous transfer
> link: https://lore.kernel.org/dmaengine/20221223022608.550697-1-mie@igel.co.jp/
> - [RFC PATCH 0/3] Deal with alignment restriction on EP side
> link: https://lore.kernel.org/linux-pci/20230113090350.1103494-1-mie@igel.co.jp/
> - [RFC PATCH v2 0/7] Introduce a vringh accessor for IO memory
> link: https://lore.kernel.org/virtualization/20230202090934.549556-1-mie@igel.co.jp/
> 
> About this patchset has 4 patches. The first of two patch is little changes
> to virtio. The third patch add APIs to easily access virtio data structure
> on PCIe Host side memory. The last one introduce a virtio-net EP device
> function. Details are in commit respectively.
> 
> Currently those network devices are testd using ping only. I'll add a
> result of performance evaluation using iperf and etc to the future version
> of this patchset.


All this feels like it'd need a virtio spec extension but I'm not 100%
sure without spending much more time understanding this.
what do you say?

> Shunsuke Mie (4):
>   virtio_pci: add a definition of queue flag in ISR
>   virtio_ring: remove const from vring getter
>   PCI: endpoint: Introduce virtio library for EP functions
>   PCI: endpoint: function: Add EP function driver to provide virtio net
>     device
> 
>  drivers/pci/endpoint/Kconfig                  |   7 +
>  drivers/pci/endpoint/Makefile                 |   1 +
>  drivers/pci/endpoint/functions/Kconfig        |  12 +
>  drivers/pci/endpoint/functions/Makefile       |   1 +
>  .../pci/endpoint/functions/pci-epf-vnet-ep.c  | 343 ++++++++++
>  .../pci/endpoint/functions/pci-epf-vnet-rc.c  | 635 ++++++++++++++++++
>  drivers/pci/endpoint/functions/pci-epf-vnet.c | 387 +++++++++++
>  drivers/pci/endpoint/functions/pci-epf-vnet.h |  62 ++
>  drivers/pci/endpoint/pci-epf-virtio.c         | 113 ++++
>  drivers/virtio/virtio_ring.c                  |   2 +-
>  include/linux/pci-epf-virtio.h                |  25 +
>  include/linux/virtio.h                        |   2 +-
>  include/uapi/linux/virtio_pci.h               |   2 +
>  13 files changed, 1590 insertions(+), 2 deletions(-)
>  create mode 100644 drivers/pci/endpoint/functions/pci-epf-vnet-ep.c
>  create mode 100644 drivers/pci/endpoint/functions/pci-epf-vnet-rc.c
>  create mode 100644 drivers/pci/endpoint/functions/pci-epf-vnet.c
>  create mode 100644 drivers/pci/endpoint/functions/pci-epf-vnet.h
>  create mode 100644 drivers/pci/endpoint/pci-epf-virtio.c
>  create mode 100644 include/linux/pci-epf-virtio.h
> 
> -- 
> 2.25.1