Re: [RESEND PATCH v5 5/5] hw/pci: ensure PCIE devices are plugged into only slot 0 of PCIE port

[Michael S. Tsirkin]

On Tue, Jun 27, 2023 at 05:59:02PM +0530, Ani Sinha wrote:
> 
> 
> > On 27-Jun-2023, at 5:53 PM, Michael S. Tsirkin <mst@redhat.com> wrote:
> > 
> > On Tue, Jun 27, 2023 at 01:58:49PM +0200, Igor Mammedov wrote:
> >> On Tue, 27 Jun 2023 15:23:04 +0530
> >> Ani Sinha <anisinha@redhat.com> wrote:
> >> 
> >>>> On 27-Jun-2023, at 2:32 PM, Igor Mammedov <imammedo@redhat.com> wrote:
> >>>> 
> >>>> On Mon, 26 Jun 2023 21:42:44 +0530
> >>>> Ani Sinha <anisinha@redhat.com> 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.  
> >>>> 
> >>>> btw, previously you mentioned ARI.
> >>>> So if we turn it on, wouldn't this patch actually become regression?  
> >>> 
> >>> If ARI breaks this, it will break other areas in QEMU too, ex anywhere 
> >>> pci_get_function_0() is used.
> >>> Regardless, I think at least the tests are worth fixing, particularly the 
> >>> mess with hd-geo-test.
> >> 
> >> I'm fine with this patch if you test it with ARI enabled and it won't break
> >> something that has been working before this patch. Just mention what 
> >> testing
> >> you've done in commit message.
> > 
> > Oh yes. That's why it was checking !vf originally. It's because the most
> > common use of ARI is SRIOV, so it works a a kind of hack.
> 
> Ok so should I put it back?
> Also I was thinking of running the qtest and avocado test mentioned in 
> https://www.qemu.org/docs/master/system/devices/igb.html . Not sure if it 
> would be enough to test ARI.

Well you need > 8 VFs for that.

> > 
> >>> 
> >>>> 
> >>>>> 
> >>>>> CC: jusual@redhat.com
> >>>>> CC: imammedo@redhat.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 | 6 ++++++
> >>>>> 1 file changed, 6 insertions(+)
> >>>>> 
> >>>>> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> >>>>> index bf38905b7d..426af133b0 100644
> >>>>> --- a/hw/pci/pci.c
> >>>>> +++ b/hw/pci/pci.c
> >>>>> @@ -64,6 +64,7 @@ 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),
> >>>>> @@ -1189,6 +1190,11 @@ static PCIDevice 
> >>>>> *do_pci_register_device(PCIDevice *pci_dev,
> >>>>>                   name);
> >>>>> 
> >>>>>       return NULL;
> >>>>> +    } else if (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;