xen: fix interrupt routing

Compared to the last version I only added a comment to the code.

- remove i440FX-xen and i440fx_write_config_xen
we don't need to intercept pci config writes to i440FX anymore;

- introduce PIIX3-xen and piix3_write_config_xen
we do need to intercept pci config write to the PCI-ISA bridge to update
the PCI link routing;

- set the number of PIIX3-xen interrupts line to 128;
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>

hw/pc.h

@@ -176,7 +176,6 @@ struct PCII440FXState;
 typedef struct PCII440FXState PCII440FXState;
 
 PCIBus *i440fx_init(PCII440FXState **pi440fx_state, int *piix_devfn, qemu_irq *pic, ram_addr_t ram_size);
-PCIBus *i440fx_xen_init(PCII440FXState **pi440fx_state, int *piix3_devfn, qemu_irq *pic, ram_addr_t ram_size);
 void i440fx_init_memory_mappings(PCII440FXState *d);
 
 /* piix4.c */

hw/pc_piix.c

@@ -124,11 +124,7 @@ static void pc_init1(ram_addr_t ram_size,
     isa_irq = qemu_allocate_irqs(isa_irq_handler, isa_irq_state, 24);
 
     if (pci_enabled) {
-        if (!xen_enabled()) {
-            pci_bus = i440fx_init(&i440fx_state, &piix3_devfn, isa_irq, ram_size);
-        } else {
-            pci_bus = i440fx_xen_init(&i440fx_state, &piix3_devfn, isa_irq, ram_size);
-        }
+        pci_bus = i440fx_init(&i440fx_state, &piix3_devfn, isa_irq, ram_size);
     } else {
         pci_bus = NULL;
         i440fx_state = NULL;

hw/piix_pci.c

@@ -40,6 +40,7 @@ typedef PCIHostState I440FXState;
 
 #define PIIX_NUM_PIC_IRQS       16      /* i8259 * 2 */
 #define PIIX_NUM_PIRQS          4ULL    /* PIRQ[A-D] */
+#define XEN_PIIX_NUM_PIRQS      128ULL
 #define PIIX_PIRQC              0x60
 
 typedef struct PIIX3State {
@@ -78,6 +79,8 @@ struct PCII440FXState {
 #define I440FX_SMRAM    0x72
 
 static void piix3_set_irq(void *opaque, int pirq, int level);
+static void piix3_write_config_xen(PCIDevice *dev,
+                               uint32_t address, uint32_t val, int len);
 
 /* return the global irq number corresponding to a given device irq
    pin. We could also use the bus number to have a more precise
@@ -173,13 +176,6 @@ static void i440fx_write_config(PCIDevice *dev,
     }
 }
 
-static void i440fx_write_config_xen(PCIDevice *dev,
-                                    uint32_t address, uint32_t val, int len)
-{
-    xen_piix_pci_write_config_client(address, val, len);
-    i440fx_write_config(dev, address, val, len);
-}
-
 static int i440fx_load_old(QEMUFile* f, void *opaque, int version_id)
 {
     PCII440FXState *d = opaque;
@@ -267,8 +263,21 @@ static PCIBus *i440fx_common_init(const char *device_name,
     d = pci_create_simple(b, 0, device_name);
     *pi440fx_state = DO_UPCAST(PCII440FXState, dev, d);
 
-    piix3 = DO_UPCAST(PIIX3State, dev,
-                      pci_create_simple_multifunction(b, -1, true, "PIIX3"));
+    /* Xen supports additional interrupt routes from the PCI devices to
+     * the IOAPIC: the four pins of each PCI device on the bus are also
+     * connected to the IOAPIC directly.
+     * These additional routes can be discovered through ACPI. */
+    if (xen_enabled()) {
+        piix3 = DO_UPCAST(PIIX3State, dev,
+                pci_create_simple_multifunction(b, -1, true, "PIIX3-xen"));
+        pci_bus_irqs(b, xen_piix3_set_irq, xen_pci_slot_get_pirq,
+                piix3, XEN_PIIX_NUM_PIRQS);
+    } else {
+        piix3 = DO_UPCAST(PIIX3State, dev,
+                pci_create_simple_multifunction(b, -1, true, "PIIX3"));
+        pci_bus_irqs(b, piix3_set_irq, pci_slot_get_pirq, piix3,
+                PIIX_NUM_PIRQS);
+    }
     piix3->pic = pic;
 
     (*pi440fx_state)->piix3 = piix3;
@@ -289,21 +298,6 @@ PCIBus *i440fx_init(PCII440FXState **pi440fx_state, int *piix3_devfn,
     PCIBus *b;
 
     b = i440fx_common_init("i440FX", pi440fx_state, piix3_devfn, pic, ram_size);
-    pci_bus_irqs(b, piix3_set_irq, pci_slot_get_pirq, (*pi440fx_state)->piix3,
-                 PIIX_NUM_PIRQS);
-
-    return b;
-}
-
-PCIBus *i440fx_xen_init(PCII440FXState **pi440fx_state, int *piix3_devfn,
-                        qemu_irq *pic, ram_addr_t ram_size)
-{
-    PCIBus *b;
-
-    b = i440fx_common_init("i440FX-xen", pi440fx_state, piix3_devfn, pic, ram_size);
-    pci_bus_irqs(b, xen_piix3_set_irq, xen_pci_slot_get_pirq,
-                 (*pi440fx_state)->piix3, PIIX_NUM_PIRQS);
-
     return b;
 }
 
@@ -365,6 +359,13 @@ static void piix3_write_config(PCIDevice *dev,
     }
 }
 
+static void piix3_write_config_xen(PCIDevice *dev,
+                               uint32_t address, uint32_t val, int len)
+{
+    xen_piix_pci_write_config_client(address, val, len);
+    piix3_write_config(dev, address, val, len);
+}
+
 static void piix3_reset(void *opaque)
 {
     PIIX3State *d = opaque;
@@ -464,14 +465,6 @@ static PCIDeviceInfo i440fx_info[] = {
         .no_hotplug   = 1,
         .init         = i440fx_initfn,
         .config_write = i440fx_write_config,
-    },{
-        .qdev.name    = "i440FX-xen",
-        .qdev.desc    = "Host bridge",
-        .qdev.size    = sizeof(PCII440FXState),
-        .qdev.vmsd    = &vmstate_i440fx,
-        .qdev.no_user = 1,
-        .init         = i440fx_initfn,
-        .config_write = i440fx_write_config_xen,
     },{
         .qdev.name    = "PIIX3",
         .qdev.desc    = "ISA bridge",
@@ -481,6 +474,15 @@ static PCIDeviceInfo i440fx_info[] = {
         .no_hotplug   = 1,
         .init         = piix3_initfn,
         .config_write = piix3_write_config,
+    },{
+        .qdev.name    = "PIIX3-xen",
+        .qdev.desc    = "ISA bridge",
+        .qdev.size    = sizeof(PIIX3State),
+        .qdev.vmsd    = &vmstate_piix3,
+        .qdev.no_user = 1,
+        .no_hotplug   = 1,
+        .init         = piix3_initfn,
+        .config_write = piix3_write_config_xen,
     },{
         /* end of list */
     }