Messages in this thread | | | Subject | Re: [PATCH 5/6] vdpa: introduce virtio pci driver | From | Jason Wang <> | Date | Mon, 8 Jun 2020 17:43:58 +0800 |
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On 2020/6/8 下午5:31, Michael S. Tsirkin wrote: > On Mon, Jun 08, 2020 at 05:18:44PM +0800, Jason Wang wrote: >> On 2020/6/8 下午2:32, Michael S. Tsirkin wrote: >>> On Mon, Jun 08, 2020 at 11:32:31AM +0800, Jason Wang wrote: >>>> On 2020/6/7 下午9:51, Michael S. Tsirkin wrote: >>>>> On Fri, Jun 05, 2020 at 04:54:17PM +0800, Jason Wang wrote: >>>>>> On 2020/6/2 下午3:08, Jason Wang wrote: >>>>>>>>> +static const struct pci_device_id vp_vdpa_id_table[] = { >>>>>>>>> + { PCI_DEVICE(PCI_VENDOR_ID_REDHAT_QUMRANET, PCI_ANY_ID) }, >>>>>>>>> + { 0 } >>>>>>>>> +}; >>>>>>>> This looks like it'll create a mess with either virtio pci >>>>>>>> or vdpa being loaded at random. Maybe just don't specify >>>>>>>> any IDs for now. Down the road we could get a >>>>>>>> distinct vendor ID or a range of device IDs for this. >>>>>>> Right, will do. >>>>>>> >>>>>>> Thanks >>>>>> Rethink about this. If we don't specify any ID, the binding won't work. >>>>> We can bind manually. It's not really for production anyway, so >>>>> not a big deal imho. >>>> I think you mean doing it via "new_id", right. >>> I really meant driver_override. This is what people have been using >>> with pci-stub for years now. >> >> Do you want me to implement "driver_overrid" in this series, or a NULL >> id_table is sufficient? > > Doesn't the pci subsystem create driver_override for all devices > on the pci bus?
Yes, I miss this.
>>>>>> How about using a dedicated subsystem vendor id for this? >>>>>> >>>>>> Thanks >>>>> If virtio vendor id is used then standard driver is expected >>>>> to bind, right? Maybe use a dedicated vendor id? >>>> I meant something like: >>>> >>>> static const struct pci_device_id vp_vdpa_id_table[] = { >>>> { PCI_DEVICE_SUB(PCI_VENDOR_ID_REDHAT_QUMRANET, PCI_ANY_ID, >>>> VP_TEST_VENDOR_ID, VP_TEST_DEVICE_ID) }, >>>> { 0 } >>>> }; >>>> >>>> Thanks >>>> >>> Then regular virtio will still bind to it. It has >>> >>> drivers/virtio/virtio_pci_common.c: { PCI_DEVICE(PCI_VENDOR_ID_REDHAT_QUMRANET, PCI_ANY_ID) }, >>> >>> >> IFCVF use this to avoid the binding to regular virtio device. > > Ow. Indeed: > > #define IFCVF_VENDOR_ID 0x1AF4 > > Which is of course not an IFCVF vendor id, it's the Red Hat vendor ID. > > I missed that. > > Does it actually work if you bind a virtio driver to it?
It works.
> I'm guessing no otherwise they wouldn't need IFC driver, right? >
Looking at the driver, they used a dedicated bar for dealing with virtqueue state save/restore. It
> > >> Looking at >> pci_match_one_device() it checks both subvendor and subdevice there. >> >> Thanks > > But IIUC there is no guarantee that driver with a specific subvendor > matches in presence of a generic one. > So either IFC or virtio pci can win, whichever binds first.
I'm not sure I get there. But I try manually bind IFCVF to qemu's virtio-net-pci, and it fails.
Thanks
> > I guess we need to blacklist IFC in virtio pci probe code. Ugh.
>
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