[Qemu-devel] [PATCH 07/10] pci: introduce pci bus pre reset

[Cao jin]

From: Chen Fan <address@hidden>

avoid repeat bus reset, here introduce a sequence ID for each time
bus hot reset, so each vfio device could know whether they've already
been reset for that sequence ID.

Signed-off-by: Chen Fan <address@hidden>
---
 hw/core/qdev.c           |  4 ++--
 hw/pci/pci.c             | 25 +++++++++++++++++++++++++
 hw/pci/pci_bridge.c      |  5 ++++-
 include/hw/pci/pci_bus.h |  4 ++++
 include/hw/qdev-core.h   |  3 +++
 5 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index 779de2b..e36fa07 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -304,14 +304,14 @@ void qdev_unplug(DeviceState *dev, Error **errp)
     }
 }
 
-static int qdev_reset_one(DeviceState *dev, void *opaque)
+int qdev_reset_one(DeviceState *dev, void *opaque)
 {
     device_reset(dev);
 
     return 0;
 }
 
-static int qbus_reset_one(BusState *bus, void *opaque)
+int qbus_reset_one(BusState *bus, void *opaque)
 {
     BusClass *bc = BUS_GET_CLASS(bus);
     if (bc->reset) {
diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index e41925e..ff978bc 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -258,6 +258,29 @@ void pci_device_reset(PCIDevice *dev)
     pci_do_device_reset(dev);
 }
 
+int pcibus_pre_reset(BusState *qbus, void *opaque)
+{
+    BusState *bus = (BusState *)opaque;
+    PCIBus *pci_bus = DO_UPCAST(PCIBus, qbus, qbus);
+    static unsigned int reset_seqid;
+
+    /*
+     * To distinguish the different reset times, we
+     * recalculate the global reset seqid with a given bus.
+     */
+    if (qbus == bus) {
+        reset_seqid++;
+        if (!reset_seqid) {
+            reset_seqid = 1;
+       }
+    }
+
+    pci_bus->bus_in_reset = true;
+    pci_bus->reset_seqid = reset_seqid;
+
+    return 0;
+}
+
 /*
  * Trigger pci bus reset under a given bus.
  * Called via qbus_reset_all on RST# assert, after the devices
@@ -277,6 +300,8 @@ static void pcibus_reset(BusState *qbus)
     for (i = 0; i < bus->nirq; i++) {
         assert(bus->irq_count[i] == 0);
     }
+
+    bus->bus_in_reset = false;
 }
 
 static void pci_host_bus_register(PCIBus *bus, DeviceState *parent)
diff --git a/hw/pci/pci_bridge.c b/hw/pci/pci_bridge.c
index 7eab9d5..6c35171 100644
--- a/hw/pci/pci_bridge.c
+++ b/hw/pci/pci_bridge.c
@@ -269,7 +269,10 @@ void pci_bridge_write_config(PCIDevice *d,
     newctl = pci_get_word(d->config + PCI_BRIDGE_CONTROL);
     if (~oldctl & newctl & PCI_BRIDGE_CTL_BUS_RESET) {
         /* Trigger hot reset on 0->1 transition. */
-        qbus_reset_all(&s->sec_bus.qbus);
+        qbus_walk_children(&s->sec_bus.qbus, NULL,
+                           pcibus_pre_reset,
+                           qdev_reset_one,
+                           qbus_reset_one, &s->sec_bus.qbus);
     }
 }
 
diff --git a/include/hw/pci/pci_bus.h b/include/hw/pci/pci_bus.h
index 7812fa9..9dd2d6c 100644
--- a/include/hw/pci/pci_bus.h
+++ b/include/hw/pci/pci_bus.h
@@ -40,11 +40,15 @@ struct PCIBus {
     int nirq;
     int *irq_count;
 
+    bool bus_in_reset;
+    uint32_t reset_seqid;
+
     NotifierWithReturnList hotplug_notifiers;
 };
 
 void pci_bus_add_hotplug_notifier(PCIBus *bus, NotifierWithReturn *notify);
 void pci_bus_remove_hotplug_notifier(NotifierWithReturn *notify);
+int pcibus_pre_reset(BusState *qbus, void *opaque);
 
 typedef struct PCIBridgeWindows PCIBridgeWindows;
 
diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index abcdee8..3d71c17 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -401,4 +401,7 @@ static inline bool qbus_is_hotpluggable(BusState *bus)
 void device_listener_register(DeviceListener *listener);
 void device_listener_unregister(DeviceListener *listener);
 
+int qdev_reset_one(DeviceState *dev, void *opaque);
+int qbus_reset_one(BusState *bus, void *opaque);
+
 #endif
-- 
1.9.3