Re: [PATCH v5 02/11] pci: add option for net failover

[Alex Williamson <alex.williamson@redhat.com>]

On Fri, 25 Oct 2019 12:52:32 +0200
Jens Freimann <jfreimann@redhat.com> wrote:

> On Wed, Oct 23, 2019 at 12:06:48PM -0600, Alex Williamson wrote:
> >On Wed, 23 Oct 2019 10:27:02 +0200
> >Jens Freimann <jfreimann@redhat.com> wrote:  
> [...]
> >> @@ -2101,6 +2104,20 @@ static void pci_qdev_realize(DeviceState *qdev, Error **errp)
> >>          }
> >>      }
> >>
> >> +    if (pci_dev->net_failover_pair_id) {
> >> +        if (!pci_is_express(pci_dev)) {
> >> +            error_setg(errp, "failover device is not a PCIExpress device");
> >> +            error_propagate(errp, local_err);
> >> +            return;
> >> +        }  
> >
> >Did we decide we don't need to test that the device is also in a
> >hotpluggable slot?  Are there also multi-function considerations that
> >should be prevented or documented?  For example, if a user tries to
> >configure both the primary and failover NICs in the same slot, I assume
> >bad things will happen.  
> 
> I added this check
> 
>         if (!(pci_dev->cap_present & QEMU_PCI_CAP_MULTIFUNCTION)
>             && (PCI_FUNC(pci_dev->devfn) == 0)) {
>             qdev->allow_unplug_during_migration = true;
>         } else {
>             error_setg(errp, "failover: primary device must be in its own "
>                               "PCI slot");
>             error_propagate(errp, local_err);
>             pci_qdev_unrealize(DEVICE(pci_dev), NULL);
>             return;
>         }
> 
> When I first add a vfio-pci with net_failover_pair_id=x,multifunction=on
> and addr=0.0 I will now get an error.
> 
> (qemu) device_add vfio-pci,...,bus=root2,net_failover_pair_id=net1,multifunction=on,addr=0.0
> Error: failover: primary device must be in its own PCI slot
> 
> If I put in a virtio-net device in slot 0 and then try to add a
> vfio-pci device in the same slot I get the following error message:
> 
> -device virtio-net-pci,...id=net1bus=root1,failover=on,multifunction=on,addr=0.0
> (qemu) device_add vfio-pci,id=hostdev1,host=0000:5e:00.2,bus=root1,net_failover_pair_id=net1,addr=0.1
> Error: PCI: slot 0 function 0 already ocuppied by virtio-net-pci,
>    new func vfio-pci cannot be exposed to guest.

Cool, looks good.  Thanks,

Alex