[Qemu-devel] [PATCH 1/1] Fix device listener interface for PCI to PCI bridges

[Don Slutz]

The commit 707ff80021ccd7a68f4b3d2c44eebf87efbb41c4 assumed that a
PCI device has a static address.  This is not true for PCI devices
that are on the secondary bus of a PCI to PCI bridge.

BIOS and/or guest OS can change the secondary bus number to a new
value at any time.

When a PCI to PCI bridge bridge is reset, the secondary bus number
is set to zero.  Normally the BIOS will set it to 255 during PCI bus
scanning so that only the PCI devices on the root can be accessed
via bus 0.  Later it is set to a number between 1 and 254.

Adjust xen_map_pcidev() to not register with Xen for secondary bus
numbers 0 and 255.

Extend the device listener interface to be called when ever the
secondary bus number is set to a usable value.  This includes
a call on unrealize if the secondary bus number was valid.

Signed-off-by: Don Slutz <address@hidden>
---

Note: Right now hvmloader in Xen does not handle PCI to PCI bridges
and so SeaBIOS does not have access to PCI device(s) on secondary
buses.  How ever domU can setup the secondary bus(es) and this patch
will restore access to these PCI devices.

 hw/core/qdev.c              | 10 ++++++++++
 hw/pci/pci_bridge.c         | 30 ++++++++++++++++++++++++++++++
 include/hw/qdev-core.h      |  2 ++
 include/hw/xen/xen_common.h | 31 +++++++++++++++++++++++++------
 trace-events                |  1 +
 5 files changed, 68 insertions(+), 6 deletions(-)

diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index b0f0f84..6a514ee 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -239,6 +239,16 @@ void device_listener_unregister(DeviceListener *listener)
     QTAILQ_REMOVE(&device_listeners, listener, link);
 }
 
+void device_listener_realize(DeviceState *dev)
+{
+    DEVICE_LISTENER_CALL(realize, Forward, dev);
+}
+
+void device_listener_unrealize(DeviceState *dev)
+{
+    DEVICE_LISTENER_CALL(unrealize, Forward, dev);
+}
+
 static void device_realize(DeviceState *dev, Error **errp)
 {
     DeviceClass *dc = DEVICE_GET_CLASS(dev);
diff --git a/hw/pci/pci_bridge.c b/hw/pci/pci_bridge.c
index 40c97b1..042680d 100644
--- a/hw/pci/pci_bridge.c
+++ b/hw/pci/pci_bridge.c
@@ -241,6 +241,18 @@ void pci_bridge_update_mappings(PCIBridge *br)
     pci_bridge_region_cleanup(br, w);
 }
 
+static void pci_bridge_realize_sub(PCIBus *b, PCIDevice *d,
+                                   void *opaque)
+{
+    device_listener_realize(DEVICE(d));
+}
+
+static void pci_bridge_unrealize_sub(PCIBus *b, PCIDevice *d,
+                                     void *opaque)
+{
+    device_listener_unrealize(DEVICE(d));
+}
+
 /* default write_config function for PCI-to-PCI bridge */
 void pci_bridge_write_config(PCIDevice *d,
                              uint32_t address, uint32_t val, int len)
@@ -248,6 +260,8 @@ void pci_bridge_write_config(PCIDevice *d,
     PCIBridge *s = PCI_BRIDGE(d);
     uint16_t oldctl = pci_get_word(d->config + PCI_BRIDGE_CONTROL);
     uint16_t newctl;
+    uint8_t oldbus = pci_get_byte(d->config + PCI_SECONDARY_BUS);
+    uint8_t newbus;
 
     pci_default_write_config(d, address, val, len);
 
@@ -265,6 +279,22 @@ void pci_bridge_write_config(PCIDevice *d,
         pci_bridge_update_mappings(s);
     }
 
+    newbus = pci_get_byte(d->config + PCI_SECONDARY_BUS);
+    if (newbus != oldbus) {
+        PCIBus *sec_bus = pci_bridge_get_sec_bus(s);
+
+        if (oldbus && oldbus != 255) {
+            pci_set_byte(d->config + PCI_SECONDARY_BUS, oldbus);
+            pci_for_each_device(sec_bus, pci_bus_num(sec_bus),
+                                pci_bridge_unrealize_sub, NULL);
+            pci_set_byte(d->config + PCI_SECONDARY_BUS, newbus);
+        }
+        if (newbus && newbus != 255) {
+            pci_for_each_device(sec_bus, pci_bus_num(sec_bus),
+                                pci_bridge_realize_sub, NULL);
+        }
+    }
+
     newctl = pci_get_word(d->config + PCI_BRIDGE_CONTROL);
     if (~oldctl & newctl & PCI_BRIDGE_CTL_BUS_RESET) {
         /* Trigger hot reset on 0->1 transition. */
diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index d4be92f..8bd38af 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -387,5 +387,7 @@ static inline bool qbus_is_hotpluggable(BusState *bus)
 
 void device_listener_register(DeviceListener *listener);
 void device_listener_unregister(DeviceListener *listener);
+void device_listener_realize(DeviceState *dev);
+void device_listener_unrealize(DeviceState *dev);
 
 #endif
diff --git a/include/hw/xen/xen_common.h b/include/hw/xen/xen_common.h
index 38f29fb..1c27d51 100644
--- a/include/hw/xen/xen_common.h
+++ b/include/hw/xen/xen_common.h
@@ -347,12 +347,31 @@ static inline void xen_map_pcidev(XenXC xc, domid_t dom,
                                   ioservid_t ioservid,
                                   PCIDevice *pci_dev)
 {
-    trace_xen_map_pcidev(ioservid, pci_bus_num(pci_dev->bus),
-                         PCI_SLOT(pci_dev->devfn), PCI_FUNC(pci_dev->devfn));
-    xc_hvm_map_pcidev_to_ioreq_server(xc, dom, ioservid,
-                                      0, pci_bus_num(pci_dev->bus),
-                                      PCI_SLOT(pci_dev->devfn),
-                                      PCI_FUNC(pci_dev->devfn));
+    if (pci_bus_is_root(pci_dev->bus)) {
+        trace_xen_map_pcidev(ioservid, 0,
+                             PCI_SLOT(pci_dev->devfn),
+                             PCI_FUNC(pci_dev->devfn));
+        xc_hvm_map_pcidev_to_ioreq_server(xc, dom, ioservid,
+                                          0, 0,
+                                          PCI_SLOT(pci_dev->devfn),
+                                          PCI_FUNC(pci_dev->devfn));
+    } else {
+        int subbus = pci_bus_num(pci_dev->bus);
+
+        if (subbus && subbus != 255) {
+            trace_xen_map_pcidev(ioservid, subbus,
+                                 PCI_SLOT(pci_dev->devfn),
+                                 PCI_FUNC(pci_dev->devfn));
+            xc_hvm_map_pcidev_to_ioreq_server(xc, dom, ioservid,
+                                              0, subbus,
+                                              PCI_SLOT(pci_dev->devfn),
+                                              PCI_FUNC(pci_dev->devfn));
+        } else {
+            trace_xen_map_pcidev_unknown(ioservid,
+                                         PCI_SLOT(pci_dev->devfn),
+                                         PCI_FUNC(pci_dev->devfn));
+        }
+    }
 }
 
 static inline void xen_unmap_pcidev(XenXC xc, domid_t dom,
diff --git a/trace-events b/trace-events
index 11387c3..63c0361 100644
--- a/trace-events
+++ b/trace-events
@@ -931,6 +931,7 @@ xen_unmap_mmio_range(uint32_t id, uint64_t start_addr, 
uint64_t end_addr) "id: %
 xen_map_portio_range(uint32_t id, uint64_t start_addr, uint64_t end_addr) "id: 
%u start: %#"PRIx64" end: %#"PRIx64
 xen_unmap_portio_range(uint32_t id, uint64_t start_addr, uint64_t end_addr) 
"id: %u start: %#"PRIx64" end: %#"PRIx64
 xen_map_pcidev(uint32_t id, uint8_t bus, uint8_t dev, uint8_t func) "id: %u 
bdf: %02x.%02x.%02x"
+xen_map_pcidev_unknown(uint32_t id, uint8_t dev, uint8_t func) "id: %u bdf: 
??.%02x.%02x"
 xen_unmap_pcidev(uint32_t id, uint8_t bus, uint8_t dev, uint8_t func) "id: %u 
bdf: %02x.%02x.%02x"
 
 # xen-mapcache.c
-- 
1.8.4