docs/libxl: Introduce CHECKPOINT_CONTEXT to support migration v2 colo streams

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Yang Hongyang <hongyang.yang@easystack.cn>
Signed-off-by: Changlong Xie <xiecl.fnst@cn.fujitsu.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>

docs/specs/libxl-migration-stream.pandoc

@@ -1,6 +1,8 @@
 % LibXenLight Domain Image Format
 % Andrew Cooper <<andrew.cooper3@citrix.com>>
-% Revision 1
+  Wen Congyang <<wency@cn.fujitsu.com>>
+  Yang Hongyang <<hongyang.yang@easystack.cn>>
+% Revision 2
 
 Introduction
 ============
@@ -119,7 +121,9 @@ type         0x00000000: END
 
              0x00000004: CHECKPOINT_END
 
-             0x00000005 - 0x7FFFFFFF: Reserved for future _mandatory_
+             0x00000005: CHECKPOINT_STATE
+
+             0x00000006 - 0x7FFFFFFF: Reserved for future _mandatory_
              records.
 
              0x80000000 - 0xFFFFFFFF: Reserved for future _optional_
@@ -249,6 +253,57 @@ A checkpoint end record marks the end of a checkpoint in the image.
 The end record contains no fields; its body_length is 0.
 
 
+CHECKPOINT\_STATE
+--------------
+
+A checkpoint state record contains the control information for checkpoint. It
+is only used by COLO, more detail please reference README.colo.
+
+     0     1     2     3     4     5     6     7 octet
+    +------------------------+------------------------+
+    | control_id             | padding                |
+    +------------------------+------------------------+
+
+--------------------------------------------------------------------
+Field            Description
+------------     ---------------------------------------------------
+control_id       0x00000000: Secondary VM is out of sync, start a new checkpoint
+                 (Primary -> Secondary)
+
+                 0x00000001: Secondary VM is suspended (Secondary -> Primary)
+
+                 0x00000002: Secondary VM is ready (Secondary -> Primary)
+
+                 0x00000003: Secondary VM is resumed (Secondary -> Primary)
+
+--------------------------------------------------------------------
+
+In COLO, Primary is running in below loop:
+
+1. Suspend primary vm
+    a. Suspend primary vm
+    b. Read _CHECKPOINT\_SVM\_SUSPENDED_ sent by secondary
+2. Checkpoint
+3. Resume primary vm
+    a. Read _CHECKPOINT\_SVM\_READY_ from secondary
+    b. Resume primary vm
+    c. Read _CHECKPOINT\_SVM\_RESUMED_ from secondary
+4. Wait a new checkpoint
+    a. Send _CHECKPOINT\_NEW_ to secondary
+
+While Secondary is running in below loop:
+
+1. Resume secondary vm
+    a. Send _CHECKPOINT\_SVM\_READY_ to primary
+    b. Resume secondary vm
+    c. Send _CHECKPOINT\_SVM\_RESUMED_ to primary
+2. Wait a new checkpoint
+    a. Read _CHECKPOINT\_NEW_ from primary
+3. Suspend secondary vm
+    a. Suspend secondary vm
+    b. Send _CHECKPOINT\_SVM\_SUSPENDED_ to primary
+4. Checkpoint
+
 Future Extensions
 =================
 

tools/libxl/libxl_sr_stream_format.h

@@ -36,6 +36,7 @@ typedef struct libxl__sr_rec_hdr
 #define REC_TYPE_EMULATOR_XENSTORE_DATA 0x00000002U
 #define REC_TYPE_EMULATOR_CONTEXT       0x00000003U
 #define REC_TYPE_CHECKPOINT_END         0x00000004U
+#define REC_TYPE_CHECKPOINT_STATE       0x00000005U
 
 typedef struct libxl__sr_emulator_hdr
 {
@@ -47,6 +48,16 @@ typedef struct libxl__sr_emulator_hdr
 #define EMULATOR_QEMU_TRADITIONAL    0x00000001U
 #define EMULATOR_QEMU_UPSTREAM       0x00000002U
 
+typedef struct libxl_sr_checkpoint_state
+{
+    uint32_t id;
+} libxl_sr_checkpoint_state;
+
+#define CHECKPOINT_NEW               0x00000000U
+#define CHECKPOINT_SVM_SUSPENDED     0x00000001U
+#define CHECKPOINT_SVM_READY         0x00000002U
+#define CHECKPOINT_SVM_RESUMED       0x00000003U
+
 #endif /* LIBXL__SR_STREAM_FORMAT_H */
 
 /*

tools/python/xen/migration/libxl.py

@@ -37,6 +37,7 @@ REC_TYPE_libxc_context          = 0x00000001
 REC_TYPE_emulator_xenstore_data = 0x00000002
 REC_TYPE_emulator_context       = 0x00000003
 REC_TYPE_checkpoint_end         = 0x00000004
+REC_TYPE_checkpoint_state       = 0x00000005
 
 rec_type_to_str = {
     REC_TYPE_end                    : "End",
@@ -44,6 +45,7 @@ rec_type_to_str = {
     REC_TYPE_emulator_xenstore_data : "Emulator xenstore data",
     REC_TYPE_emulator_context       : "Emulator context",
     REC_TYPE_checkpoint_end         : "Checkpoint end",
+    REC_TYPE_checkpoint_state       : "Checkpoint state"
 }
 
 # emulator_* header
@@ -212,6 +214,11 @@ class VerifyLibxl(VerifyBase):
         if len(content) != 0:
             raise RecordError("Checkpoint end record with non-zero length")
 
+    def verify_record_checkpoint_state(self, content):
+        """ Checkpoint state """
+        if len(content) == 0:
+            raise RecordError("Checkpoint state record with zero length")
+
 
 record_verifiers = {
     REC_TYPE_end:
@@ -224,4 +231,6 @@ record_verifiers = {
         VerifyLibxl.verify_record_emulator_context,
     REC_TYPE_checkpoint_end:
         VerifyLibxl.verify_record_checkpoint_end,
+    REC_TYPE_checkpoint_state:
+        VerifyLibxl.verify_record_checkpoint_state,
 }