Re: [PATCH] hw/pci: prevent hotplug of devices on pcie-root-ports with wrong devfn address

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Jun 14, 2023 at 06:01:50PM +0530, Ani Sinha wrote:
> PCIE root ports only allow one device on slot 0/function 0.


Why do you say this? PCI devices can be multifunction.

> When hotplugging a
> device on a pcie root port, make sure that the device address passed is
> always 0x00 that represents slot 0 and function 0. Any other slot value and
> function value would be illegal on a root port.
> 
> 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>
> ---
>  hw/pci/pci.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> Note:
> I tested this with both native and acpi hotplug enabled on pcie. The
> check seems to work on both.
> 
> (qemu)  netdev_add socket,id=hostnet1,listen=:1234
> (qemu) device_add e1000e,netdev=hostnet1,mac=00:11:22:33:44:03,id=net1,bus=pci.6,addr=0x2.0x5
> Error: PCI: slot 2 function 5 is not valid for e1000e
> (qemu) device_add e1000e,netdev=hostnet1,mac=00:11:22:33:44:03,id=net1,bus=pci.6,addr=0x0.0
> (qemu) info network
> net1: index=0,type=nic,model=e1000e,macaddr=00:11:22:33:44:03
>  \ hostnet1: index=0,type=socket,
> (qemu) device_del net1
> (qemu) info network
> hostnet1: index=0,type=socket,
> 
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index bf38905b7d..bc39322dfd 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 +1190,14 @@ static PCIDevice *do_pci_register_device(PCIDevice *pci_dev,
>                     name);
>  
>         return NULL;
> +    } else if (dev->hotplugged &&
> +               !pci_is_vf(pci_dev) &&
> +               pcie_has_upstream_port(pci_dev) && devfn) {
> +        /* For an upstream PCIE port, we only support one device at slot 0 */
> +        error_setg(errp, "PCI: slot %d function %d is not valid for %s",
> +                   PCI_SLOT(devfn), PCI_FUNC(devfn), name);
> +        return NULL;
> +
>      }
>  
>      pci_dev->devfn = devfn;
> -- 
> 2.39.1