memory: Don't set migration bitmap when without migration

Similar to 9460dee4b2 ("memory: do not touch code dirty bitmap unless
TCG is enabled", 2015-06-05) but for the migration bitmap - we can
skip the MIGRATION bitmap update if migration not enabled.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20190603065056.25211-4-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

3 files changed, 14 insertions, 2 deletions

diff --git a/include/exec/memory.h b/include/exec/memory.h
index 2c5cdffa31..70d6f7e451 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -46,6 +46,8 @@
         OBJECT_GET_CLASS(IOMMUMemoryRegionClass, (obj), \
                          TYPE_IOMMU_MEMORY_REGION)
 
+extern bool global_dirty_log;
+
 typedef struct MemoryRegionOps MemoryRegionOps;
 typedef struct MemoryRegionMmio MemoryRegionMmio;
 
diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
index 44dcc98de6..0a532c3963 100644
--- a/include/exec/ram_addr.h
+++ b/include/exec/ram_addr.h
@@ -349,8 +349,13 @@ static inline void cpu_physical_memory_set_dirty_lebitmap(unsigned long *bitmap,
             if (bitmap[k]) {
                 unsigned long temp = leul_to_cpu(bitmap[k]);
 
-                atomic_or(&blocks[DIRTY_MEMORY_MIGRATION][idx][offset], temp);
                 atomic_or(&blocks[DIRTY_MEMORY_VGA][idx][offset], temp);
+
+                if (global_dirty_log) {
+                    atomic_or(&blocks[DIRTY_MEMORY_MIGRATION][idx][offset],
+                              temp);
+                }
+
                 if (tcg_enabled()) {
                     atomic_or(&blocks[DIRTY_MEMORY_CODE][idx][offset], temp);
                 }
@@ -367,6 +372,11 @@ static inline void cpu_physical_memory_set_dirty_lebitmap(unsigned long *bitmap,
         xen_hvm_modified_memory(start, pages << TARGET_PAGE_BITS);
     } else {
         uint8_t clients = tcg_enabled() ? DIRTY_CLIENTS_ALL : DIRTY_CLIENTS_NOCODE;
+
+        if (!global_dirty_log) {
+            clients &= ~(1 << DIRTY_MEMORY_MIGRATION);
+        }
+
         /*
          * bitmap-traveling is faster than memory-traveling (for addr...)
          * especially when most of the memory is not dirty.
diff --git a/memory.c b/memory.c
index 480f3d989b..93486a71d7 100644
--- a/memory.c
+++ b/memory.c
@@ -38,7 +38,7 @@
 static unsigned memory_region_transaction_depth;
 static bool memory_region_update_pending;
 static bool ioeventfd_update_pending;
-static bool global_dirty_log = false;
+bool global_dirty_log;
 
 static QTAILQ_HEAD(, MemoryListener) memory_listeners
     = QTAILQ_HEAD_INITIALIZER(memory_listeners);