[dpdk-dev] [PATCH 2/3] net/vdpa_virtio_pci: introduce vdpa sample driver
Wang, Xiao W
xiao.w.wang at intel.com
Thu Feb 8 03:23:40 CET 2018
Hi Maxime,
> -----Original Message-----
> From: Maxime Coquelin [mailto:maxime.coquelin at redhat.com]
> Sent: Tuesday, February 6, 2018 10:24 PM
> To: Wang, Xiao W <xiao.w.wang at intel.com>; dev at dpdk.org
> Cc: Tan, Jianfeng <jianfeng.tan at intel.com>; Bie, Tiwei <tiwei.bie at intel.com>;
> yliu at fridaylinux.org; Liang, Cunming <cunming.liang at intel.com>; Daly, Dan
> <dan.daly at intel.com>; Wang, Zhihong <zhihong.wang at intel.com>
> Subject: Re: [PATCH 2/3] net/vdpa_virtio_pci: introduce vdpa sample driver
>
> Hi Xiao,
>
> On 02/04/2018 03:55 PM, Xiao Wang wrote:
> > This driver is a reference sample of making vDPA device driver based
> > on vhost lib, this driver uses a standard virtio-net PCI device as
> > vDPA device, it can serve as a backend for a virtio-net pci device
> > in nested VM.
> >
> > The key driver ops implemented are:
> >
> > * vdpa_virtio_eng_init
> > Mapping virtio pci device with VFIO into userspace, and read device
> > capability and intialize internal data.
> >
> > * vdpa_virtio_eng_uninit
> > Release the mapped device.
> >
> > * vdpa_virtio_info_query
> > Device capability reporting, e.g. queue number, features.
> >
> > * vdpa_virtio_dev_config
> > With the guest virtio information provideed by vhost lib, this
> > function configures device and IOMMU to set up vhost datapath,
> > which includes: Rx/Tx vring, VFIO interrupt, kick relay.
> >
> > * vdpa_virtio_dev_close
> > Unset the stuff that are configured previously by dev_conf.
> >
> > This driver requires the virtio device supports VIRTIO_F_IOMMU_PLATFORM
> > , because the buffer address written in desc is IOVA.
> >
> > Because vDPA driver needs to set up MSI-X vector to interrupt the guest,
> > only vfio-pci is supported currently.
> >
> > Signed-off-by: Xiao Wang<xiao.w.wang at intel.com>
> > ---
> > config/common_base | 6 +
> > config/common_linuxapp | 1 +
> > drivers/net/Makefile | 1 +
> > drivers/net/vdpa_virtio_pci/Makefile | 31 +
> > .../net/vdpa_virtio_pci/rte_eth_vdpa_virtio_pci.c | 1527
> ++++++++++++++++++++
> > .../rte_vdpa_virtio_pci_version.map | 4 +
> > mk/rte.app.mk | 1 +
> > 7 files changed, 1571 insertions(+)
> > create mode 100644 drivers/net/vdpa_virtio_pci/Makefile
> > create mode 100644 drivers/net/vdpa_virtio_pci/rte_eth_vdpa_virtio_pci.c
> > create mode 100644
> drivers/net/vdpa_virtio_pci/rte_vdpa_virtio_pci_version.map
>
> Is there a specific constraint that makes you expose PCI functions and
> duplicate a lot of vfio code into the driver?
The existing vfio code doesn't fit VDPA well, this vDPA driver needs to program IOMMU for a vDPA device with a VM's memory table.
While the eal/vfio uses a struct vfio_cfg to takes all regular devices and add them to a single vfio_container, and program IOMMU with DPDK process's memory table.
This driver doing PCI VFIO initialization itself can avoid affecting the global vfio_cfg structure.
>
> Wouldn't it be better (if possible) to use RTE_PMD_REGISTER_PCI() & co.
> to benefit from all the existing infrastructure?
RTE_PMD_REGISTER_PCI() & co will make this driver as PCI driver (physical device), then this will conflict with the virtio_pmd.
So I make vDPA device driver as a vdev driver.
>
> Maxime
Thanks for the comments,
Xiao
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