ram: Move last_req_rb to RAMState

It was on MigrationState when it is only used inside ram.c for
postcopy.  Problem is that we need to access it without being able to
pass it RAMState directly.
Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NPeter Xu <peterx@redhat.com>

include/migration/migration.h

@@ -189,8 +189,6 @@ struct MigrationState
     /* Queue of outstanding page requests from the destination */
     QemuMutex src_page_req_mutex;
     QSIMPLEQ_HEAD(src_page_requests, MigrationSrcPageRequest) src_page_requests;
-    /* The RAMBlock used in the last src_page_request */
-    RAMBlock *last_req_rb;
     /* The semaphore is used to notify COLO thread that failover is finished */
     QemuSemaphore colo_exit_sem;
 

migration/migration.c

@@ -1126,7 +1126,6 @@ MigrationState *migrate_init(const MigrationParams *params)
     s->postcopy_after_devices = false;
     s->postcopy_requests = 0;
     s->migration_thread_running = false;
-    s->last_req_rb = NULL;
     error_free(s->error);
     s->error = NULL;
 

migration/ram.c

@@ -204,6 +204,8 @@ struct RAMState {
     QemuMutex bitmap_mutex;
     /* Ram Bitmap protected by RCU */
     RAMBitmap *ram_bitmap;
+    /* The RAMBlock used in the last src_page_requests */
+    RAMBlock *last_req_rb;
 };
 typedef struct RAMState RAMState;
 
@@ -1226,12 +1228,13 @@ int ram_save_queue_pages(MigrationState *ms, const char *rbname,
                          ram_addr_t start, ram_addr_t len)
 {
     RAMBlock *ramblock;
+    RAMState *rs = &ram_state;
 
     ms->postcopy_requests++;
     rcu_read_lock();
     if (!rbname) {
         /* Reuse last RAMBlock */
-        ramblock = ms->last_req_rb;
+        ramblock = rs->last_req_rb;
 
         if (!ramblock) {
             /*
@@ -1249,7 +1252,7 @@ int ram_save_queue_pages(MigrationState *ms, const char *rbname,
             error_report("ram_save_queue_pages no block '%s'", rbname);
             goto err;
         }
-        ms->last_req_rb = ramblock;
+        rs->last_req_rb = ramblock;
     }
     trace_ram_save_queue_pages(ramblock->idstr, start, len);
     if (start+len > ramblock->used_length) {