Re: [PATCH for-9.2 v15 04/11] s390x/pci: Check for multifunction after device realization

["Cédric Le Goater" <clg@redhat.com>]

+Matthew +Eric

Side note for the maintainers :

Before this change, the igb device, which is multifunction, was working
fine under Linux.

Was there a fix in Linux since :

   57da367b9ec4 ("s390x/pci: forbid multifunction pci device")
   6069bcdeacee ("s390x/pci: Move some hotplug checks to the pre_plug handler")

?

s390 PCI devices do not have extended capabilities, so the igb device
does not expose the SRIOV capability and only the PF is accessible but
it doesn't seem to be an issue. (Btw, CONFIG_PCI_IOV is set to y in the
default Linux config which is unexpected)

Thanks,

C.



On 8/23/24 07:00, Akihiko Odaki wrote:
> The SR-IOV PFs set the multifunction bits during device realization so
> check them after that. This forbids adding SR-IOV devices to s390x.
> 
> Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
> ---
>   hw/s390x/s390-pci-bus.c | 14 ++++++--------
>   1 file changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c
> index 3e57d5faca18..00b2c1f6157b 100644
> --- a/hw/s390x/s390-pci-bus.c
> +++ b/hw/s390x/s390-pci-bus.c
> @@ -971,14 +971,7 @@ static void s390_pcihost_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
>                       "this device");
>       }
>   
> -    if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
> -        PCIDevice *pdev = PCI_DEVICE(dev);
> -
> -        if (pdev->cap_present & QEMU_PCI_CAP_MULTIFUNCTION) {
> -            error_setg(errp, "multifunction not supported in s390");
> -            return;
> -        }
> -    } else if (object_dynamic_cast(OBJECT(dev), TYPE_S390_PCI_DEVICE)) {
> +    if (object_dynamic_cast(OBJECT(dev), TYPE_S390_PCI_DEVICE)) {
>           S390PCIBusDevice *pbdev = S390_PCI_DEVICE(dev);
>   
>           if (!s390_pci_alloc_idx(s, pbdev)) {
> @@ -1069,6 +1062,11 @@ static void s390_pcihost_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
>       } else if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
>           pdev = PCI_DEVICE(dev);
>   
> +        if (pdev->cap_present & QEMU_PCI_CAP_MULTIFUNCTION) {
> +            error_setg(errp, "multifunction not supported in s390");
> +            return;
> +        }
> +
>           if (!dev->id) {
>               /* In the case the PCI device does not define an id */
>               /* we generate one based on the PCI address         */
>