[v2,1/2] memory: Introduce start_global variable in dirty bitmap sync

Commit Message

zhukeqian March 10, 2020, 9:17 a.m. UTC

In the cpu_physical_memory_sync_dirty_bitmap func, use start_global
variable to make code more clear. And the addr variable is only used
in slow path, so move it to slow path.

Signed-off-by: Keqian Zhu <[e-mail]>
---
 include/exec/ram_addr.h | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

Patch

diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
index 5e59a3d8d7..8311efb7bc 100644
--- a/include/exec/ram_addr.h
+++ b/include/exec/ram_addr.h
@@ -445,14 +445,13 @@  uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb,
                                                ram_addr_t length,
                                                uint64_t *real_dirty_pages)
 {
-    ram_addr_t addr;
-    unsigned long word = BIT_WORD((start + rb->offset) >> TARGET_PAGE_BITS);
+    ram_addr_t start_global = start + rb->offset;
+    unsigned long word = BIT_WORD(start_global >> TARGET_PAGE_BITS);
     uint64_t num_dirty = 0;
     unsigned long *dest = rb->bmap;
 
     /* start address and length is aligned at the start of a word? */
-    if (((word * BITS_PER_LONG) << TARGET_PAGE_BITS) ==
-         (start + rb->offset) &&
+    if (((word * BITS_PER_LONG) << TARGET_PAGE_BITS) == start_global &&
         !(length & ((BITS_PER_LONG << TARGET_PAGE_BITS) - 1))) {
         int k;
         int nr = BITS_TO_LONGS(length >> TARGET_PAGE_BITS);
@@ -495,11 +494,11 @@  uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb,
             memory_region_clear_dirty_bitmap(rb->mr, start, length);
         }
     } else {
-        ram_addr_t offset = rb->offset;
+        ram_addr_t addr;
 
         for (addr = 0; addr < length; addr += TARGET_PAGE_SIZE) {
             if (cpu_physical_memory_test_and_clear_dirty(
-                        start + addr + offset,
+                        start_global + addr,
                         TARGET_PAGE_SIZE,
                         DIRTY_MEMORY_MIGRATION)) {
                 *real_dirty_pages += 1;