> On 04-Jul-2023, at 6:18 PM, Igor Mammedov <imamm...@redhat.com> wrote:
>
> On Tue, 4 Jul 2023 21:02:09 +0900
> Akihiko Odaki <akihiko.od...@daynix.com> wrote:
>
>> On 2023/07/04 20:59, Ani Sinha wrote:
>>>
>>>
>>>> On 04-Jul-2023, at 5:24 PM, Akihiko Odaki <akihiko.od...@daynix.com> wrote:
>>>>
>>>> On 2023/07/04 20:25, 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. Add a warning to let users know when
>>>>> the
>>>>> invalid configuration is used. We may enforce this more strongly later on
>>>>> once
>>>>> we get more clarity on whether we are introducing a bad regression for
>>>>> users
>>>>> currenly using the wrong configuration.
>>>>> The change has been tested to not break or alter behaviors of ARI capable
>>>>> devices by instantiating seven vfs on an emulated igb device (the maximum
>>>>> number of vfs the linux igb driver supports). The vfs instantiated
>>>>> correctly
>>>>> and are seen to have non-zero device/slot numbers in the conventional PCI
>>>>> BDF
>>>>> representation.
>>>>> CC: jus...@redhat.com
>>>>> CC: imamm...@redhat.com
>>>>> CC: m...@redhat.com
>>>>> CC: akihiko.od...@daynix.com
>>>>> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2128929
>>>>> Signed-off-by: Ani Sinha <anisi...@redhat.com>
>>>>> Reviewed-by: Julia Suvorova <jus...@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..47517ba3db 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),
>>>>> @@ -2121,6 +2122,20 @@ static void pci_qdev_realize(DeviceState *qdev,
>>>>> Error **errp)
>>>>> }
>>>>> }
>>>>> + /*
>>>>> + * 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.
>>>>
>>>> You don't have to mention SR/IOV; it affects all ARI-capable devices. A PF
>>>> can also have non-zero slot number in the conventional interpretation so
>>>> you shouldn't call it vf either.
>>>
>>> Can you please help write a comment that explains this properly for all
>>> cases - ARI/non-ARI, PFs and VFs? Once everyone agrees that its clear and
>>> correct, I will re-spin.
>>
>> Simply, you can say:
>> With ARI, the slot number field in the conventional PCI interpretation
>> can have a non-zero value as the field bits are reused to extend the
>> function number bits. Ignore that case.
>
> mentioning 'conventional PCI interpretation' in comment and then immediately
> checking 'pci_is_express(pci_dev)' is confusing. Since comment belongs
> only to PCIE branch it would be better to talk in only about PCIe stuff
> and referring to relevant portions of spec.
Ok so how about this?
* With ARI, devices can have non-zero slot in the traditional BDF
* representation as all five bits reserved for slot addresses are
* also used for function bits. Ignore that case.
> (for example see how it's done in kernel code: only_one_child(...)
>
> PS:
> kernel can be forced to scan for !0 device numbers, but that's rather
> a hack, so we shouldn't really care about that.
>
>>
>>>
>>>>
>>>>> + */
>>>>> + if (pci_is_express(pci_dev) &&
>>>>> + !pcie_find_capability(pci_dev, PCI_EXT_CAP_ID_ARI) &&
>>>>> + pcie_has_upstream_port(pci_dev) &&
>>>>> + PCI_SLOT(pci_dev->devfn)) {
>>>>> + warn_report("PCI: slot %d is not valid for %s,"
>>>>> + " parent device only allows plugging into slot 0.",
>>>>> + PCI_SLOT(pci_dev->devfn), pci_dev->name);
>>>>> + }
>>>>> +
>>>>> if (pci_dev->failover_pair_id) {
>>>>> if (!pci_bus_is_express(pci_get_bus(pci_dev))) {
>>>>> error_setg(errp, "failover primary device must be on "
