pcie: Add link speed and width fields to PCIESlot

Add fields allowing the PCIe link speed and width of a PCIESlot to
be configured, with an instance_post_init callback on the root port
parent class to set defaults.  This allows child classes to set these
via properties or via their own instance_init callback, without
requiring all implementions to support arbitrary user selected values.

Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Tested-by: Geoffrey McRae <geoff@hostfission.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/pci-bridge/pcie_root_port.c

@@ -140,6 +140,19 @@ static Property rp_props[] = {
     DEFINE_PROP_END_OF_LIST()
 };
 
+static void rp_instance_post_init(Object *obj)
+{
+    PCIESlot *s = PCIE_SLOT(obj);
+
+    if (!s->speed) {
+        s->speed = QEMU_PCI_EXP_LNK_2_5GT;
+    }
+
+    if (!s->width) {
+        s->width = QEMU_PCI_EXP_LNK_X1;
+    }
+}
+
 static void rp_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
@@ -157,6 +170,7 @@ static void rp_class_init(ObjectClass *klass, void *data)
 static const TypeInfo rp_info = {
     .name          = TYPE_PCIE_ROOT_PORT,
     .parent        = TYPE_PCIE_SLOT,
+    .instance_post_init = rp_instance_post_init,
     .class_init    = rp_class_init,
     .abstract      = true,
     .class_size = sizeof(PCIERootPortClass),

include/hw/pci/pcie_port.h

@@ -49,6 +49,10 @@ struct PCIESlot {
     /* pci express switch port with slot */
     uint8_t     chassis;
     uint16_t    slot;
+
+    PCIExpLinkSpeed speed;
+    PCIExpLinkWidth width;
+
     QLIST_ENTRY(PCIESlot) next;
 };