pcie: Mangle types to match topology

Windows will fail to start drivers for devices with an Endpoint type
PCIe capability attached to a Root Complex (code 10 - Device cannot
start).  The proper type for such a device is Root Complex Integrated
Endpoint.  Devices don't care which they are, so do this conversion
automatically.

This allows the Windows driver to load for nec-usb-xhci when attached
to pcie.0 of a q35 machine.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/pci/pcie.c

@@ -48,6 +48,19 @@ int pcie_cap_init(PCIDevice *dev, uint8_t offset, uint8_t type, uint8_t port)
 
     assert(pci_is_express(dev));
 
+    /*
+     * Mangle type to convert Endpoints to Root Complex Integrated Endpoints.
+     * Windows will report Code 10 (device cannot start) for regular Endpoints
+     * on the Root Complex.
+     */
+    if (pci_bus_is_express(dev->bus) && pci_bus_is_root(dev->bus)) {
+        switch (type) {
+        case PCI_EXP_TYPE_ENDPOINT:
+            type = PCI_EXP_TYPE_RC_END;
+            break;
+        }
+    }
+
     pos = pci_add_capability(dev, PCI_CAP_ID_EXP, offset,
                                  PCI_EXP_VER2_SIZEOF);
     if (pos < 0) {