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

[Ani Sinha <anisinha@redhat.com>]

PCIE root ports only allow one device on slot 0/function 0. 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