Date:   Mon, 24 Apr 2023 19:06:47 +0900
From:   Shunsuke Mie <mie@...l.co.jp>
To:     Frank Li <frank.li@....com>
Cc:     Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Manivannan Sadhasivam <mani@...nel.org>,
        Kishon Vijay Abraham I <kishon@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>, Jon Mason <jdmason@...zu.us>,
        Randy Dunlap <rdunlap@...radead.org>,
        Ren Zhijie <renzhijie2@...wei.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>
Subject: Re: [EXT] [RFC PATCH 0/3] Introduce a PCIe endpoint virtio console

2023年4月19日(水) 1:42 Frank Li <frank.li@....com>:
>
>
>
> > -----Original Message-----
> > From: Shunsuke Mie <mie@...l.co.jp>
> > Sent: Tuesday, April 18, 2023 5:31 AM
> > To: Frank Li <frank.li@....com>; Lorenzo Pieralisi <lpieralisi@...nel.org>
> > Cc: Krzysztof Wilczyński <kw@...ux.com>; Manivannan Sadhasivam
> > <mani@...nel.org>; Kishon Vijay Abraham I <kishon@...nel.org>; Bjorn
> > Helgaas <bhelgaas@...gle.com>; Michael S. Tsirkin <mst@...hat.com>;
> > Jason Wang <jasowang@...hat.com>; Jon Mason <jdmason@...zu.us>;
> > Randy Dunlap <rdunlap@...radead.org>; Ren Zhijie
> > <renzhijie2@...wei.com>; linux-kernel@...r.kernel.org; linux-
> > pci@...r.kernel.org; virtualization@...ts.linux-foundation.org
> > Subject: Re: [EXT] [RFC PATCH 0/3] Introduce a PCIe endpoint virtio console
> >
> > Caution: EXT Email
> >
> > On 2023/04/18 0:19, Frank Li wrote:
> > >
> > >> -----Original Message-----
> > >> From: Shunsuke Mie <mie@...l.co.jp>
> > >> Sent: Sunday, April 16, 2023 9:12 PM
> > >> To: Frank Li <frank.li@....com>; Lorenzo Pieralisi <lpieralisi@...nel.org>
> > >> Cc: Krzysztof Wilczyński <kw@...ux.com>; Manivannan Sadhasivam
> > >> <mani@...nel.org>; Kishon Vijay Abraham I <kishon@...nel.org>; Bjorn
> > >> Helgaas <bhelgaas@...gle.com>; Michael S. Tsirkin <mst@...hat.com>;
> > >> Jason Wang <jasowang@...hat.com>; Jon Mason <jdmason@...zu.us>;
> > >> Randy Dunlap <rdunlap@...radead.org>; Ren Zhijie
> > >> <renzhijie2@...wei.com>; linux-kernel@...r.kernel.org; linux-
> > >> pci@...r.kernel.org; virtualization@...ts.linux-foundation.org
> > >> Subject: Re: [EXT] [RFC PATCH 0/3] Introduce a PCIe endpoint virtio
> > console
> > >>
> > >> Caution: EXT Email
> > >>
> > >> On 2023/04/14 23:39, Frank Li wrote:
> > >>>> -----Original Message-----
> > >>>> From: Shunsuke Mie <mie@...l.co.jp>
> > >>>> Sent: Friday, April 14, 2023 7:39 AM
> > >>>> To: Lorenzo Pieralisi <lpieralisi@...nel.org>
> > >>>> Cc: Krzysztof Wilczyński <kw@...ux.com>; Manivannan Sadhasivam
> > >>>> <mani@...nel.org>; Kishon Vijay Abraham I <kishon@...nel.org>;
> > Bjorn
> > >>>> Helgaas <bhelgaas@...gle.com>; Michael S. Tsirkin
> > <mst@...hat.com>;
> > >>>> Jason Wang <jasowang@...hat.com>; Shunsuke Mie
> > <mie@...l.co.jp>;
> > >>>> Frank Li <frank.li@....com>; Jon Mason <jdmason@...zu.us>; Randy
> > >>>> Dunlap <rdunlap@...radead.org>; Ren Zhijie
> > <renzhijie2@...wei.com>;
> > >>>> linux-kernel@...r.kernel.org; linux-pci@...r.kernel.org;
> > >>>> virtualization@...ts.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?
> > > I go through your code again.  I think I understand why you need pci-epf-
> > vcon.c.
> > > Actually,  my means is like virtio_mmio_probe.
> > >
> > > vm_dev->vdev.id.device = readl(vm_dev->base +
> > VIRTIO_MMIO_DEVICE_ID);
> > > vm_dev->vdev.id.vendor = readl(vm_dev->base +
> > VIRTIO_MMIO_VENDOR_ID);
> > >
> > > I am not sure that if VIRTIO_MMIO_VENDOR_ID and
> > VIRTIO_MMIO_DEVICE_ID
> > > reuse PCI's vendor ID and Device ID.  If yes, you can directly get such
> > information
> > > from epf.  If no,  a customer field can been added at epf driver.
> > >
> > > So you needn't write pci-epf-vcon  and pci-epf-vnet .....
> > >
> > > Of cause it will be wonderful if directly use virtio_mmio_probe by dynmatic
> > create platform
> > > Devices.  It may have some difficult because pci memory map requirement.
> > I think that some fields are shared between the vdev and epf device.
> > However, we need to implement device emulation because each virtio
> > device
> > has its specific set of tasks. For example, the virtio-net device has a
> > control queue, and the driver can request MAC filters, VLANs, and other
> > settings via this queue. These requests have to be processed by the virtio
> > device that we are implementing in pci-epf-vnet.
> >
> > The simplest virtio-console device doesn’t have these tasks, but the other
> > virtio devices requireprocessing them.
> >
> > That's why the current pci-epf-virtio design requires a specific
> > implementation for each virtio device.
> >
> > Is this what you meant
>
> I see. Thank you for explain.
> Thing may become complex. How to implement composite at EPF driver?
> Such as console + net
I'm not sure your suggestion. Could you tell me the advantages?
> >
> > >
> > >>> 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/
> > %2F&data=05%7C01%7Cfrank.li%40nxp.com%7C80a237184ff4420a96de08db
> > 3ff80d78%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C63817410683
> > 2489955%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV
> > 2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=LSP
> > LeFzTYpUVTZpymoM00Es9kOpxlN90%2BDM6ceDJMFE%3D&reserved=0
> > >> %2F&data=05%7C01%7Cfrank.li%40nxp.com%7Cff59a16f88c643913e3908
> > db3
> > >>
> > ee91ca8%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C63817294315
> > >>
> > 3821831%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV
> > >>
> > 2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=hTB
> > >> 5UDaJoJfta9ohMG%2BrxCVJY34ANn10iSLP9iCHX3M%3D&reserved=0
> > >>>> 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%2Bs5
> > Mm
> > >> svo
> > >>>> %3D&reserved=0
> > >>>> - [RFC PATCH v2 0/7] Introduce a vringh accessor for IO memory
> > >>>> link:
> > >>>>
> > >>
> > https://lore.k/
> > %2F&data=05%7C01%7Cfrank.li%40nxp.com%7C80a237184ff4420a96de08db
> > 3ff80d78%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C63817410683
> > 2489955%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV
> > 2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=LSP
> > LeFzTYpUVTZpymoM00Es9kOpxlN90%2BDM6ceDJMFE%3D&reserved=0
> > >> %2F&data=05%7C01%7Cfrank.li%40nxp.com%7Cff59a16f88c643913e3908
> > db3
> > >>
> > ee91ca8%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C63817294315
> > >>
> > 3821831%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV
> > >>
> > 2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=hTB
> > >> 5UDaJoJfta9ohMG%2BrxCVJY34ANn10iSLP9iCHX3M%3D&reserved=0
> > >>>> 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%2Fn7flCN20eEMZpZYTX2WI
> > Z0
> > >> %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
Best regards,
Shunsuike

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