On Fri, Mar 16, 2018 at 9:34 AM, Michael S. Tsirkin <mst@xxxxxxxxxx> wrote: > On Thu, Mar 15, 2018 at 11:42:41AM -0700, Alexander Duyck wrote: >> From: Alexander Duyck <alexander.h.duyck@xxxxxxxxx> >> >> Hardware-realized virtio_pci devices can implement SR-IOV, so this >> patch enables its use. The device in question is an upcoming Intel >> NIC that implements both a virtio_net PF and virtio_net VFs. These >> are hardware realizations of what has been up to now been a software >> interface. >> >> The device in question has the following 4-part PCI IDs: >> >> PF: vendor: 1af4 device: 1041 subvendor: 8086 subdevice: 15fe >> VF: vendor: 1af4 device: 1041 subvendor: 8086 subdevice: 05fe >> >> The patch currently needs no check for device ID, because the callback >> will never be made for devices that do not assert the capability or >> when run on a platform incapable of SR-IOV. >> >> One reason for this patch is because the hardware requires the >> vendor ID of a VF to be the same as the vendor ID of the PF that >> created it. So it seemed logical to simply have a fully-functioning >> virtio_net PF create the VFs. This patch makes that possible. >> >> Reviewed-by: Christoph Hellwig <hch@xxxxxx> >> Signed-off-by: Mark Rustad <mark.d.rustad@xxxxxxxxx> >> Signed-off-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxx> > > So if and when virtio PFs can manage the VFs, then we can > add a feature bit for that? > Seems reasonable. Yes. If nothing else you may not even need a feature bit depending on how things go. One of the reasons why Mark called out the subvendor/subdevice was because that might be able to be used to identify the specific hardware that is providing the SR-IOV feature so in the future if it is added to virtio itself then you could exclude devices like this by just limiting things based on subvendor/subdevice IDs. > Also, I am guessing that hardware implementations will want > to add things like stong memory barriers - I guess we > will add new feature bits for that too down the road? That piece I don't have visibility into at this time. Perhaps Dan might have more visibility into future plans on what this might need. Thanks. - Alex
