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From:   Shunsuke Mie <mie@igel.co.jp>
Date:   Tue, 7 Feb 2023 19:17:14 +0900
Message-ID: <CANXvt5q_qgLuAfF7dxxrqUirT_Ld4B=POCq8JcB9uPRvCGDiKg@mail.gmail.com>
Subject: Re: [RFC PATCH 0/4] PCI: endpoint: Introduce a virtio-net EP function
To:     "Michael S. Tsirkin" <mst@redhat.com>
Cc:     Lorenzo Pieralisi <lpieralisi@kernel.org>,
        =?UTF-8?Q?Krzysztof_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
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2023=E5=B9=B42=E6=9C=885=E6=97=A5(=E6=97=A5) 19:02 Michael S. Tsirkin <mst@=
redhat.com>:
>
> 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. I=
t
> > 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 patchse=
t
> > are following:
> > - [PATCH 1/2] dmaengine: dw-edma: Fix to change for continuous transfer
> > link: https://lore.kernel.org/dmaengine/20221223022608.550697-1-mie@ige=
l.co.jp/
> > - [RFC PATCH 0/3] Deal with alignment restriction on EP side
> > link: https://lore.kernel.org/linux-pci/20230113090350.1103494-1-mie@ig=
el.co.jp/
> > - [RFC PATCH v2 0/7] Introduce a vringh accessor for IO memory
> > link: https://lore.kernel.org/virtualization/20230202090934.549556-1-mi=
e@igel.co.jp/
> >
> > About this patchset has 4 patches. The first of two patch is little cha=
nges
> > to virtio. The third patch add APIs to easily access virtio data struct=
ure
> > 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 vers=
ion
> > 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?
This patch shows the virtio-net device as pcie device. Could you tell
me what part
of the spec are you concerned about?

> > 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
>

Best,
Shunsuke