pci: Add INTx routing notifier

This per-device notifier shall be triggered by any interrupt router
along the path of a device's legacy interrupt signal on routing changes.
For simplicity reasons and as this is a slow path anyway, no further
details on the routing changes are provided. Instead, the callback is
expected to use pci_device_route_intx_to_irq to check the effect of the
change.

Will be used by KVM PCI device assignment and VFIO.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

3 files changed, 32 insertions, 0 deletions

diff --git a/hw/pci.c b/hw/pci.c
index e80599f058..94601f28f9 100644
--- a/hw/pci.c
+++ b/hw/pci.c
@@ -1086,6 +1086,29 @@ PCIINTxRoute pci_device_route_intx_to_irq(PCIDevice *dev, int pin)
     return bus->route_intx_to_irq(bus->irq_opaque, pin);
 }
 
+void pci_bus_fire_intx_routing_notifier(PCIBus *bus)
+{
+    PCIDevice *dev;
+    PCIBus *sec;
+    int i;
+
+    for (i = 0; i < ARRAY_SIZE(bus->devices); ++i) {
+        dev = bus->devices[i];
+        if (dev && dev->intx_routing_notifier) {
+            dev->intx_routing_notifier(dev);
+        }
+        QLIST_FOREACH(sec, &bus->child, sibling) {
+            pci_bus_fire_intx_routing_notifier(sec);
+        }
+    }
+}
+
+void pci_device_set_intx_routing_notifier(PCIDevice *dev,
+                                          PCIINTxRoutingNotifier notifier)
+{
+    dev->intx_routing_notifier = notifier;
+}
+
 /***********************************************************/
 /* monitor info on PCI */
 
diff --git a/hw/pci.h b/hw/pci.h
index 7f7f88c6b9..e96e8a7e54 100644
--- a/hw/pci.h
+++ b/hw/pci.h
@@ -182,6 +182,7 @@ typedef struct PCIDeviceClass {
     const char *romfile;
 } PCIDeviceClass;
 
+typedef void (*PCIINTxRoutingNotifier)(PCIDevice *dev);
 typedef int (*MSIVectorUseNotifier)(PCIDevice *dev, unsigned int vector,
                                       MSIMessage msg);
 typedef void (*MSIVectorReleaseNotifier)(PCIDevice *dev, unsigned int vector);
@@ -259,6 +260,9 @@ struct PCIDevice {
     MemoryRegion rom;
     uint32_t rom_bar;
 
+    /* INTx routing notifier */
+    PCIINTxRoutingNotifier intx_routing_notifier;
+
     /* MSI-X notifiers */
     MSIVectorUseNotifier msix_vector_use_notifier;
     MSIVectorReleaseNotifier msix_vector_release_notifier;
@@ -318,6 +322,9 @@ PCIBus *pci_register_bus(DeviceState *parent, const char *name,
                          uint8_t devfn_min, int nirq);
 void pci_bus_set_route_irq_fn(PCIBus *, pci_route_irq_fn);
 PCIINTxRoute pci_device_route_intx_to_irq(PCIDevice *dev, int pin);
+void pci_bus_fire_intx_routing_notifier(PCIBus *bus);
+void pci_device_set_intx_routing_notifier(PCIDevice *dev,
+                                          PCIINTxRoutingNotifier notifier);
 void pci_device_reset(PCIDevice *dev);
 void pci_bus_reset(PCIBus *bus);
 
diff --git a/hw/piix_pci.c b/hw/piix_pci.c
index 8ece07c182..c497a014af 100644
--- a/hw/piix_pci.c
+++ b/hw/piix_pci.c
@@ -423,6 +423,8 @@ static void piix3_write_config(PCIDevice *dev,
     if (ranges_overlap(address, len, PIIX_PIRQC, 4)) {
         PIIX3State *piix3 = DO_UPCAST(PIIX3State, dev, dev);
         int pic_irq;
+
+        pci_bus_fire_intx_routing_notifier(piix3->dev.bus);
         piix3_update_irq_levels(piix3);
         for (pic_irq = 0; pic_irq < PIIX_NUM_PIC_IRQS; pic_irq++) {
             piix3_set_irq_pic(piix3, pic_irq);