hw/isa/piix3: Avoid Xen-specific variant of piix3_write_config()

Subscribe to pci_bus_fire_intx_routing_notifier() instead which allows for
having a common piix3_write_config() for the PIIX3 device models.

While at it, move the subscription into machine code to facilitate resolving
TYPE_PIIX3_XEN_DEVICE.

In a possible future followup, pci_bus_fire_intx_routing_notifier() could
be adjusted in such a way that subscribing to it doesn't require
knowledge of the device firing it.

Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Tested-by: Chuck Zmudzinski <brchuckz@aol.com>
Message-Id: <20230312120221.99183-5-shentey@gmail.com>
Message-Id: <20230403074124.3925-6-shentey@gmail.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>

hw/i386/pc_piix.c

@@ -90,6 +90,21 @@ static int pc_pci_slot_get_pirq(PCIDevice *pci_dev, int pci_intx)
     return (pci_intx + slot_addend) & 3;
 }
 
+static void piix_intx_routing_notifier_xen(PCIDevice *dev)
+{
+    int i;
+
+    /* Scan for updates to PCI link routes (0x60-0x63). */
+    for (i = 0; i < PIIX_NUM_PIRQS; i++) {
+        uint8_t v = dev->config_read(dev, PIIX_PIRQCA + i, 1);
+        if (v & 0x80) {
+            v = 0;
+        }
+        v &= 0xf;
+        xen_set_pci_link_route(i, v);
+    }
+}
+
 /* PC hardware initialisation */
 static void pc_init1(MachineState *machine,
                      const char *host_type, const char *pci_type)
@@ -241,6 +256,9 @@ static void pc_init1(MachineState *machine,
         pci_dev = pci_create_simple_multifunction(pci_bus, -1, true, type);
 
         if (xen_enabled()) {
+            pci_device_set_intx_routing_notifier(
+                        pci_dev, piix_intx_routing_notifier_xen);
+
             /*
              * Xen supports additional interrupt routes from the PCI devices to
              * the IOAPIC: the four pins of each PCI device on the bus are also

hw/isa/piix3.c

@@ -122,26 +122,6 @@ static void piix3_write_config(PCIDevice *dev,
     }
 }
 
-static void piix3_write_config_xen(PCIDevice *dev,
-                                   uint32_t address, uint32_t val, int len)
-{
-    int i;
-
-    /* Scan for updates to PCI link routes (0x60-0x63). */
-    for (i = 0; i < len; i++) {
-        uint8_t v = (val >> (8 * i)) & 0xff;
-        if (v & 0x80) {
-            v = 0;
-        }
-        v &= 0xf;
-        if (((address + i) >= PIIX_PIRQCA) && ((address + i) <= PIIX_PIRQCD)) {
-            xen_set_pci_link_route(address + i - PIIX_PIRQCA, v);
-        }
-    }
-
-    piix3_write_config(dev, address, val, len);
-}
-
 static void piix3_reset(DeviceState *dev)
 {
     PIIX3State *d = PIIX3_PCI_DEVICE(dev);
@@ -405,7 +385,7 @@ static void piix3_xen_class_init(ObjectClass *klass, void *data)
 {
     PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
 
-    k->config_write = piix3_write_config_xen;
+    k->config_write = piix3_write_config;
     k->realize = piix3_realize;
 }