pci: Add pci_device_route_intx_to_irq

Device assigned on KVM needs to know the mode
(enabled/inverted/disabled) and the IRQ number that a given device
triggers in the attached interrupt controller.

Add a PCI IRQ path discovery function that walks from a given device to
the host bridge, and gets this information.  For
this purpose, a host bridge callback function is introduced:
route_intx_to_irq. It is so far only implemented by the PIIX3, other
host bridges can be added later on as required.

Will be used for KVM PCI device assignment and VFIO.

Based on patch by Jan Kiszka, with minor tweaks.

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

1 files changed, 12 insertions, 0 deletions

diff --git a/hw/pci.h b/hw/pci.h
index 6983b2f..7f7f88c 100644
--- a/hw/pci.h
+++ b/hw/pci.h
@@ -141,6 +141,15 @@ enum {
 #define PCI_DEVICE_GET_CLASS(obj) \
      OBJECT_GET_CLASS(PCIDeviceClass, (obj), TYPE_PCI_DEVICE)
 
+typedef struct PCIINTxRoute {
+    enum {
+        PCI_INTX_ENABLED,
+        PCI_INTX_INVERTED,
+        PCI_INTX_DISABLED,
+    } mode;
+    int irq;
+} PCIINTxRoute;
+
 typedef struct PCIDeviceClass {
     DeviceClass parent_class;
 
@@ -278,6 +287,7 @@ MemoryRegion *pci_address_space_io(PCIDevice *dev);
 
 typedef void (*pci_set_irq_fn)(void *opaque, int irq_num, int level);
 typedef int (*pci_map_irq_fn)(PCIDevice *pci_dev, int irq_num);
+typedef PCIINTxRoute (*pci_route_irq_fn)(void *opaque, int pin);
 
 typedef enum {
     PCI_HOTPLUG_DISABLED,
@@ -306,6 +316,8 @@ PCIBus *pci_register_bus(DeviceState *parent, const char *name,
                          MemoryRegion *address_space_mem,
                          MemoryRegion *address_space_io,
                          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_device_reset(PCIDevice *dev);
 void pci_bus_reset(PCIBus *bus);