pci: avoid destroying bridge address space windows in a transaction

Calling memory_region_destroy() in a transaction is illegal (and aborts),
as until the transaction is committed, the region remains live.

Fix by moving destruction until after the transaction commits.  This requires
having an extra set of regions, so the new and old regions can coexist.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 28 insertions, 22 deletions

diff --git a/hw/pci_bridge.c b/hw/pci_bridge.c
index 5c6455f6fa..4680501e4e 100644
--- a/hw/pci_bridge.c
+++ b/hw/pci_bridge.c
@@ -151,58 +151,63 @@ static void pci_bridge_init_alias(PCIBridge *bridge, MemoryRegion *alias,
     memory_region_add_subregion_overlap(parent_space, base, alias, 1);
 }
 
-static void pci_bridge_cleanup_alias(MemoryRegion *alias,
-                                     MemoryRegion *parent_space)
-{
-    memory_region_del_subregion(parent_space, alias);
-    memory_region_destroy(alias);
-}
-
-static void pci_bridge_region_init(PCIBridge *br)
+static PCIBridgeWindows *pci_bridge_region_init(PCIBridge *br)
 {
     PCIBus *parent = br->dev.bus;
+    PCIBridgeWindows *w = g_new(PCIBridgeWindows, 1);
     uint16_t cmd = pci_get_word(br->dev.config + PCI_COMMAND);
 
-    pci_bridge_init_alias(br, &br->alias_pref_mem,
+    pci_bridge_init_alias(br, &w->alias_pref_mem,
                           PCI_BASE_ADDRESS_MEM_PREFETCH,
                           "pci_bridge_pref_mem",
                           &br->address_space_mem,
                           parent->address_space_mem,
                           cmd & PCI_COMMAND_MEMORY);
-    pci_bridge_init_alias(br, &br->alias_mem,
+    pci_bridge_init_alias(br, &w->alias_mem,
                           PCI_BASE_ADDRESS_SPACE_MEMORY,
                           "pci_bridge_mem",
                           &br->address_space_mem,
                           parent->address_space_mem,
                           cmd & PCI_COMMAND_MEMORY);
-    pci_bridge_init_alias(br, &br->alias_io,
+    pci_bridge_init_alias(br, &w->alias_io,
                           PCI_BASE_ADDRESS_SPACE_IO,
                           "pci_bridge_io",
                           &br->address_space_io,
                           parent->address_space_io,
                           cmd & PCI_COMMAND_IO);
    /* TODO: optinal VGA and VGA palette snooping support. */
+
+    return w;
 }
 
-static void pci_bridge_region_cleanup(PCIBridge *br)
+static void pci_bridge_region_del(PCIBridge *br, PCIBridgeWindows *w)
 {
     PCIBus *parent = br->dev.bus;
-    pci_bridge_cleanup_alias(&br->alias_io,
-                             parent->address_space_io);
-    pci_bridge_cleanup_alias(&br->alias_mem,
-                             parent->address_space_mem);
-    pci_bridge_cleanup_alias(&br->alias_pref_mem,
-                             parent->address_space_mem);
+
+    memory_region_del_subregion(parent->address_space_io, &w->alias_io);
+    memory_region_del_subregion(parent->address_space_mem, &w->alias_mem);
+    memory_region_del_subregion(parent->address_space_mem, &w->alias_pref_mem);
+}
+
+static void pci_bridge_region_cleanup(PCIBridge *br, PCIBridgeWindows *w)
+{
+    memory_region_destroy(&w->alias_io);
+    memory_region_destroy(&w->alias_mem);
+    memory_region_destroy(&w->alias_pref_mem);
+    g_free(w);
 }
 
 static void pci_bridge_update_mappings(PCIBridge *br)
 {
+    PCIBridgeWindows *w = br->windows;
+
     /* Make updates atomic to: handle the case of one VCPU updating the bridge
      * while another accesses an unaffected region. */
     memory_region_transaction_begin();
-    pci_bridge_region_cleanup(br);
-    pci_bridge_region_init(br);
+    pci_bridge_region_del(br, br->windows);
+    br->windows = pci_bridge_region_init(br);
     memory_region_transaction_commit();
+    pci_bridge_region_cleanup(br, w);
 }
 
 /* default write_config function for PCI-to-PCI bridge */
@@ -326,7 +331,7 @@ int pci_bridge_initfn(PCIDevice *dev)
     memory_region_init(&br->address_space_mem, "pci_bridge_pci", INT64_MAX);
     sec_bus->address_space_io = &br->address_space_io;
     memory_region_init(&br->address_space_io, "pci_bridge_io", 65536);
-    pci_bridge_region_init(br);
+    br->windows = pci_bridge_region_init(br);
     QLIST_INIT(&sec_bus->child);
     QLIST_INSERT_HEAD(&parent->child, sec_bus, sibling);
     return 0;
@@ -338,7 +343,8 @@ void pci_bridge_exitfn(PCIDevice *pci_dev)
     PCIBridge *s = DO_UPCAST(PCIBridge, dev, pci_dev);
     assert(QLIST_EMPTY(&s->sec_bus.child));
     QLIST_REMOVE(&s->sec_bus, sibling);
-    pci_bridge_region_cleanup(s);
+    pci_bridge_region_del(s, s->windows);
+    pci_bridge_region_cleanup(s, s->windows);
     memory_region_destroy(&s->address_space_mem);
     memory_region_destroy(&s->address_space_io);
     /* qbus_free() is called automatically by qdev_free() */