memory: Add global-locking property to memory regions

This introduces the memory region property "global_locking". It is true
by default. By setting it to false, a device model can request BQL-free
dispatching of region accesses to its r/w handlers. The actual BQL
break-up will be provided in a separate patch.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Frederic Konrad <fred.konrad@greensocs.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1434646046-27150-4-git-send-email-pbonzini@redhat.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/include/exec/memory.h b/include/exec/memory.h
index 8ae004eb06..0ebdc55506 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -180,6 +180,7 @@ struct MemoryRegion {
     bool rom_device;
     bool warning_printed; /* For reservations */
     bool flush_coalesced_mmio;
+    bool global_locking;
     MemoryRegion *alias;
     hwaddr alias_offset;
     int32_t priority;
@@ -825,6 +826,31 @@ void memory_region_set_flush_coalesced(MemoryRegion *mr);
 void memory_region_clear_flush_coalesced(MemoryRegion *mr);
 
 /**
+ * memory_region_set_global_locking: Declares the access processing requires
+ *                                   QEMU's global lock.
+ *
+ * When this is invoked, accesses to the memory region will be processed while
+ * holding the global lock of QEMU. This is the default behavior of memory
+ * regions.
+ *
+ * @mr: the memory region to be updated.
+ */
+void memory_region_set_global_locking(MemoryRegion *mr);
+
+/**
+ * memory_region_clear_global_locking: Declares that access processing does
+ *                                     not depend on the QEMU global lock.
+ *
+ * By clearing this property, accesses to the memory region will be processed
+ * outside of QEMU's global lock (unless the lock is held on when issuing the
+ * access request). In this case, the device model implementing the access
+ * handlers is responsible for synchronization of concurrency.
+ *
+ * @mr: the memory region to be updated.
+ */
+void memory_region_clear_global_locking(MemoryRegion *mr);
+
+/**
  * memory_region_add_eventfd: Request an eventfd to be triggered when a word
  *                            is written to a location.
  *