Re: [PATCH v6 5/5] hw/pci: ensure PCIE devices are plugged into only slot 0 of PCIE port

[Ani Sinha]

> On 29-Jun-2023, at 7:54 PM, Michael S. Tsirkin <mst@redhat.com> wrote:
> 
> On Thu, Jun 29, 2023 at 09:37:07AM +0530, Ani Sinha wrote:
>> PCI Express ports only have one slot, so PCI Express devices can only be
>> plugged into slot 0 on a PCIE port. Enforce it.
>> 
>> The change has been tested to not break ARI by instantiating seven vfs on an
>> emulated igb device (the maximum number of vfs the linux igb driver 
>> supports).
> 
> I guess we need to test with some other device then? 7 VFs is same
> slot so hardly a good test.

No its not the same slot. Its using different slots/device numbers. I checked 
that.
The same patch was failing without the vf check.

> 
>> The vfs are seen to have non-zero device/slot numbers in the conventional
>> PCI BDF representation.
>> 
>> CC: jusual@redhat.com
>> CC: imammedo@redhat.com
>> CC: akihiko.odaki@daynix.com
>> 
>> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2128929
>> Signed-off-by: Ani Sinha <anisinha@redhat.com>
>> Reviewed-by: Julia Suvorova <jusual@redhat.com>
>> ---
>> hw/pci/pci.c | 15 +++++++++++++++
>> 1 file changed, 15 insertions(+)
>> 
>> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
>> index e2eb4c3b4a..0320ac2bb3 100644
>> --- a/hw/pci/pci.c
>> +++ b/hw/pci/pci.c
>> @@ -65,6 +65,7 @@ bool pci_available = true;
>> static char *pcibus_get_dev_path(DeviceState *dev);
>> static char *pcibus_get_fw_dev_path(DeviceState *dev);
>> static void pcibus_reset(BusState *qbus);
>> +static bool pcie_has_upstream_port(PCIDevice *dev);
>> 
>> static Property pci_props[] = {
>>     DEFINE_PROP_PCI_DEVFN("addr", PCIDevice, devfn, -1),
>> @@ -1190,6 +1191,20 @@ static PCIDevice *do_pci_register_device(PCIDevice 
>> *pci_dev,
>>                    name);
>> 
>>        return NULL;
>> +    } /*
>> +       * With SRIOV and ARI, vfs can have non-zero slot in the conventional
>> +       * PCI interpretation as all five bits reserved for slot addresses are
>> +       * also used for function bits for the various vfs. Ignore that case.
>> +       * It is too early here to check for ARI capabilities in the PCI 
>> config
>> +       * space. Hence, we check for a vf device instead.
>> +       */
>> +    else if (!pci_is_vf(pci_dev) &&
>> +             pcie_has_upstream_port(pci_dev) &&
>> +             PCI_SLOT(devfn)) {
>> +        error_setg(errp, "PCI: slot %d is not valid for %s,"
>> +                   " parent device only allows plugging into slot 0.",
>> +                   PCI_SLOT(devfn), name);
>> +        return NULL;
>>     }
>> 
>>     pci_dev->devfn = devfn;
>> -- 
>> 2.39.1
>