[PATCH] xen: fix interrupt routing

[<stefano.stabellini@eu.citrix.com>]

From: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

Match the routing informations built by seabios:

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

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

- remove xen_pci_slot_get_pirq
we are now using the same link routing as seabios and qemu so we don't
need a diffirent get_pirq function;

- fix xen_piix3_set_irq
we always inject one of the 4 pci intx, so we can use
xc_hvm_set_isa_irq_level to inject the interrupt. Use pci_irqs as
initialized by seabios to map a pirq into an ISA irq. This has the
benefit of removing all the calls to xc_hvm_set_pci_intx_level that
doesn't work correctly anymore because from the same device number and
intx Xen calculates a different PCI link compared to Qemu and Seabios.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---
 hw/piix_pci.c |   21 ++++++++++++---------
 xen-all.c     |   16 ++++++++--------
 2 files changed, 20 insertions(+), 17 deletions(-)

diff --git a/hw/piix_pci.c b/hw/piix_pci.c
index 7f1c4cc..aae6a48 100644
--- a/hw/piix_pci.c
+++ b/hw/piix_pci.c
@@ -78,6 +78,8 @@ 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 +175,6 @@ 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;
@@ -301,7 +296,8 @@ PCIBus *i440fx_xen_init(PCII440FXState **pi440fx_state, int *piix3_devfn,
     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->dev.config_write = piix3_write_config_xen;
+    pci_bus_irqs(b, xen_piix3_set_irq, pci_slot_get_pirq,
                  (*pi440fx_state)->piix3, PIIX_NUM_PIRQS);
 
     return b;
@@ -365,6 +361,13 @@ 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;
@@ -471,7 +474,7 @@ static PCIDeviceInfo i440fx_info[] = {
         .qdev.vmsd    = &vmstate_i440fx,
         .qdev.no_user = 1,
         .init         = i440fx_initfn,
-        .config_write = i440fx_write_config_xen,
+        .config_write = i440fx_write_config,
     },{
         .qdev.name    = "PIIX3",
         .qdev.desc    = "ISA bridge",
diff --git a/xen-all.c b/xen-all.c
index 0eac202..7d7863f 100644
--- a/xen-all.c
+++ b/xen-all.c
@@ -70,17 +70,16 @@ typedef struct XenIOState {
     Notifier exit;
 } XenIOState;
 
-/* Xen specific function for piix pci */
+/* pci_irqs as initialized by seabios */
+uint8_t pci_irqs[4] = {
+    10, 10, 11, 11
+};
 
-int xen_pci_slot_get_pirq(PCIDevice *pci_dev, int irq_num)
-{
-    return irq_num + ((pci_dev->devfn >> 3) << 2);
-}
+/* Xen specific function for piix pci */
 
-void xen_piix3_set_irq(void *opaque, int irq_num, int level)
+void xen_piix3_set_irq(void *opaque, int pirq, int level)
 {
-    xc_hvm_set_pci_intx_level(xen_xc, xen_domid, 0, 0, irq_num >> 2,
-                              irq_num & 3, level);
+    xc_hvm_set_isa_irq_level(xen_xc, xen_domid, pci_irqs[pirq], level);
 }
 
 void xen_piix_pci_write_config_client(uint32_t address, uint32_t val, int len)
@@ -95,6 +94,7 @@ void xen_piix_pci_write_config_client(uint32_t address, uint32_t val, int len)
         }
         v &= 0xf;
         if (((address + i) >= 0x60) && ((address + i) <= 0x63)) {
+            pci_irqs[address + i - 0x60] = v;
             xc_hvm_set_pci_link_route(xen_xc, xen_domid, address + i - 0x60, v);
         }
     }
-- 
1.7.2.3