Re: [PATCH 1/3] vDPA/ifcvf: deduce VIRTIO device ID when probe

[Zhu Lingshan <lingshan.zhu@xxxxxxxxxxxxxxx>]

On 4/15/2021 11:30 AM, Jason Wang wrote:
> 在 2021/4/14 下午5:18, Zhu Lingshan 写道:
> > This commit deduces VIRTIO device ID as device type when probe,
> > then ifcvf_vdpa_get_device_id() can simply return the ID.
> > ifcvf_vdpa_get_features() and ifcvf_vdpa_get_config_size()
> > can work properly based on the device ID.
> >
> > Signed-off-by: Zhu Lingshan <lingshan.zhu@xxxxxxxxx>
> > ---
> >   drivers/vdpa/ifcvf/ifcvf_base.h |  1 +
> >   drivers/vdpa/ifcvf/ifcvf_main.c | 22 ++++++++++------------
> >   2 files changed, 11 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h 
> > b/drivers/vdpa/ifcvf/ifcvf_base.h
> > index b2eeb16b9c2c..1c04cd256fa7 100644
> > --- a/drivers/vdpa/ifcvf/ifcvf_base.h
> > +++ b/drivers/vdpa/ifcvf/ifcvf_base.h
> > @@ -84,6 +84,7 @@ struct ifcvf_hw {
> >       u32 notify_off_multiplier;
> >       u64 req_features;
> >       u64 hw_features;
> > +    u32 dev_type;
> >       struct virtio_pci_common_cfg __iomem *common_cfg;
> >       void __iomem *net_cfg;
> >       struct vring_info vring[IFCVF_MAX_QUEUE_PAIRS * 2];
> > diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c 
> > b/drivers/vdpa/ifcvf/ifcvf_main.c
> > index 44d7586019da..99b0a6b4c227 100644
> > --- a/drivers/vdpa/ifcvf/ifcvf_main.c
> > +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
> > @@ -323,19 +323,9 @@ static u32 ifcvf_vdpa_get_generation(struct 
> > vdpa_device *vdpa_dev)
> >     static u32 ifcvf_vdpa_get_device_id(struct vdpa_device *vdpa_dev)
> >   {
> > -    struct ifcvf_adapter *adapter = vdpa_to_adapter(vdpa_dev);
> > -    struct pci_dev *pdev = adapter->pdev;
> > -    u32 ret = -ENODEV;
> > -
> > -    if (pdev->device < 0x1000 || pdev->device > 0x107f)
> > -        return ret;
> > -
> > -    if (pdev->device < 0x1040)
> > -        ret =  pdev->subsystem_device;
> > -    else
> > -        ret =  pdev->device - 0x1040;
> > +    struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
> >   -    return ret;
> > +    return vf->dev_type;
> >   }
> >     static u32 ifcvf_vdpa_get_vendor_id(struct vdpa_device *vdpa_dev)
> > @@ -466,6 +456,14 @@ static int ifcvf_probe(struct pci_dev *pdev, 
> > const struct pci_device_id *id)
> >       pci_set_drvdata(pdev, adapter);
> >         vf = &adapter->vf;
> > +    if (pdev->device < 0x1000 || pdev->device > 0x107f)
> > +        return -EOPNOTSUPP;
> > +
> > +    if (pdev->device < 0x1040)
> > +        vf->dev_type =  pdev->subsystem_device;
> > +    else
> > +        vf->dev_type =  pdev->device - 0x1040;
>
>
> So a question here, is the device a transtional device or modern one?
>
> If it's a transitonal one, can it swtich endianess automatically or not?
>
> Thanks
Hi Jason,

This driver should drive both modern and transitional devices as we 
discussed before.
If it's a transitional one, it will act as a modern device by default, 
legacy mode is a fail-over path.
For vDPA, it has to support VIRTIO_1 and ACCESS_PLATFORM, so it must in 
modern mode.
I think we don't need to worry about endianess for legacy mode.

Thanks
Zhu Lingshan
> > +
> >       vf->base = pcim_iomap_table(pdev);
> >         adapter->pdev = pdev;