[Qemu-devel] [PATCH 2/3] migration/ram.c: start of cpu_physical_memory_sync_dirty_bitmap is always 0

[Wei Yang <richardw.yang@linux.intel.com>]

Since start of cpu_physical_memory_sync_dirty_bitmap is always 0, we can
remove this parameter and simplify the calculation a bit.

Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
---
 include/exec/ram_addr.h | 15 ++++++---------
 migration/ram.c         |  2 +-
 2 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
index 9ecd911c3e..3dfb2d52fb 100644
--- a/include/exec/ram_addr.h
+++ b/include/exec/ram_addr.h
@@ -409,18 +409,16 @@ static inline void cpu_physical_memory_clear_dirty_range(ram_addr_t start,
 
 static inline
 uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb,
-                                               ram_addr_t start,
                                                ram_addr_t length,
                                                uint64_t *real_dirty_pages)
 {
     ram_addr_t addr;
-    unsigned long word = BIT_WORD((start + rb->offset) >> TARGET_PAGE_BITS);
+    unsigned long word = BIT_WORD(rb->offset >> 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) &&
+    /* offset and length is aligned at the start of a word? */
+    if (((word * BITS_PER_LONG) << TARGET_PAGE_BITS) == (rb->offset) &&
         !(length & ((BITS_PER_LONG << TARGET_PAGE_BITS) - 1))) {
         int k;
         int nr = BITS_TO_LONGS(length >> TARGET_PAGE_BITS);
@@ -428,14 +426,13 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb,
         unsigned long idx = (word * BITS_PER_LONG) / DIRTY_MEMORY_BLOCK_SIZE;
         unsigned long offset = BIT_WORD((word * BITS_PER_LONG) %
                                         DIRTY_MEMORY_BLOCK_SIZE);
-        unsigned long page = BIT_WORD(start >> TARGET_PAGE_BITS);
 
         rcu_read_lock();
 
         src = atomic_rcu_read(
                 &ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION])->blocks;
 
-        for (k = page; k < page + nr; k++) {
+        for (k = 0; k < nr; k++) {
             if (src[idx][offset]) {
                 unsigned long bits = atomic_xchg(&src[idx][offset], 0);
                 unsigned long new_dirty;
@@ -458,11 +455,11 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb,
 
         for (addr = 0; addr < length; addr += TARGET_PAGE_SIZE) {
             if (cpu_physical_memory_test_and_clear_dirty(
-                        start + addr + offset,
+                        addr + offset,
                         TARGET_PAGE_SIZE,
                         DIRTY_MEMORY_MIGRATION)) {
                 *real_dirty_pages += 1;
-                long k = (start + addr) >> TARGET_PAGE_BITS;
+                long k = addr >> TARGET_PAGE_BITS;
                 if (!test_and_set_bit(k, dest)) {
                     num_dirty++;
                 }
diff --git a/migration/ram.c b/migration/ram.c
index 9948b2d021..1def8122e9 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -1646,7 +1646,7 @@ static void migration_bitmap_sync_range(RAMState *rs, RAMBlock *rb,
                                         ram_addr_t length)
 {
     rs->migration_dirty_pages +=
-        cpu_physical_memory_sync_dirty_bitmap(rb, 0, length,
+        cpu_physical_memory_sync_dirty_bitmap(rb, length,
                                               &rs->num_dirty_pages_period);
 }
 
-- 
2.19.1