XBZRLE cache size should not be larger than guest memory size

Signed-off-by: NOrit Wasserman <owasserm@redhat.com>
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

migration.c

@@ -479,6 +479,13 @@ void qmp_migrate_set_cache_size(int64_t value, Error **errp)
         return;
     }
 
+    /* Cache should not be larger than guest ram size */
+    if (value > ram_bytes_total()) {
+        error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
+                  "exceeds guest ram size ");
+        return;
+    }
+
     new_size = xbzrle_cache_resize(value);
     if (new_size < 0) {
         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",