[Qemu-devel] [PATCH 4/10] Add dirty tracking for live migration

[Anthony Liguori <aliguori@us.ibm.com>]

This patch adds a dirty tracking bit for live migration.  We use 0x08 because
kqemu uses 0x04.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

diff --git a/cpu-all.h b/cpu-all.h
index d350b30..fdac353 100644
--- a/cpu-all.h
+++ b/cpu-all.h
@@ -944,6 +944,7 @@ int cpu_memory_rw_debug(CPUState *env, target_ulong addr,
 
 #define VGA_DIRTY_FLAG  0x01
 #define CODE_DIRTY_FLAG 0x02
+#define MIGRATION_DIRTY_FLAG 0x08
 
 /* read dirty bit (return 0 or 1) */
 static inline int cpu_physical_memory_is_dirty(ram_addr_t addr)
@@ -966,6 +967,10 @@ void cpu_physical_memory_reset_dirty(ram_addr_t start, ram_addr_t end,
                                      int dirty_flags);
 void cpu_tlb_update_dirty(CPUState *env);
 
+int cpu_physical_memory_set_dirty_tracking(int enable);
+
+int cpu_physical_memory_get_dirty_tracking(void);
+
 void dump_exec_info(FILE *f,
                     int (*cpu_fprintf)(FILE *f, const char *fmt, ...));
 
diff --git a/exec.c b/exec.c
index 3ab4ad0..9dba5c8 100644
--- a/exec.c
+++ b/exec.c
@@ -38,6 +38,7 @@
 #include "qemu-common.h"
 #include "tcg.h"
 #include "hw/hw.h"
+#include "osdep.h"
 #if defined(CONFIG_USER_ONLY)
 #include <qemu.h>
 #endif
@@ -113,6 +114,7 @@ ram_addr_t phys_ram_size;
 int phys_ram_fd;
 uint8_t *phys_ram_base;
 uint8_t *phys_ram_dirty;
+static int in_migration;
 static ram_addr_t phys_ram_alloc_offset = 0;
 #endif
 
@@ -1777,6 +1779,17 @@ void cpu_physical_memory_reset_dirty(ram_addr_t start, ram_addr_t end,
     }
 }
 
+int cpu_physical_memory_set_dirty_tracking(int enable)
+{
+    in_migration = enable;
+    return 0;
+}
+
+int cpu_physical_memory_get_dirty_tracking(void)
+{
+    return in_migration;
+}
+
 static inline void tlb_update_dirty(CPUTLBEntry *tlb_entry)
 {
     ram_addr_t ram_addr;
@@ -2932,9 +2945,19 @@ void stl_phys_notdirty(target_phys_addr_t addr, uint32_t val)
         io_index = (pd >> IO_MEM_SHIFT) & (IO_MEM_NB_ENTRIES - 1);
         io_mem_write[io_index][2](io_mem_opaque[io_index], addr, val);
     } else {
-        ptr = phys_ram_base + (pd & TARGET_PAGE_MASK) +
-            (addr & ~TARGET_PAGE_MASK);
+        unsigned long addr1 = (pd & TARGET_PAGE_MASK) + (addr & ~TARGET_PAGE_MASK);
+        ptr = phys_ram_base + addr1;
         stl_p(ptr, val);
+
+        if (unlikely(in_migration)) {
+            if (!cpu_physical_memory_is_dirty(addr1)) {
+                /* invalidate code */
+                tb_invalidate_phys_page_range(addr1, addr1 + 4, 0);
+                /* set dirty bit */
+                phys_ram_dirty[addr1 >> TARGET_PAGE_BITS] |=
+                    (0xff & ~CODE_DIRTY_FLAG);
+            }
+        }
     }
 }