[Qemu-devel] [PATCH v3 12/47] Return path: Control commands

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Add two src->dest commands:
   * OPENRP - To request that the destination open the return path
   * REQACK - Request an acknowledge from the destination

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 include/migration/migration.h |  2 ++
 include/sysemu/sysemu.h       |  4 +++
 savevm.c                      | 57 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 63 insertions(+)

diff --git a/include/migration/migration.h b/include/migration/migration.h
index e23947a..173775b 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -45,6 +45,8 @@ typedef struct MigrationState MigrationState;
 /* State for the incoming migration */
 struct MigrationIncomingState {
     QEMUFile *file;
+
+    QEMUFile *return_path;
 };
 
 MigrationIncomingState *migration_incoming_get_current(void);
diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index a0a91e3..4dd6ba0 100644
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -84,6 +84,8 @@ void qemu_announce_self(void);
 /* Subcommands for QEMU_VM_COMMAND */
 enum qemu_vm_cmd {
     QEMU_VM_CMD_INVALID = 0,   /* Must be 0 */
+    QEMU_VM_CMD_OPENRP,        /* Tell the dest to open the Return path */
+    QEMU_VM_CMD_REQACK,        /* Request an ACK on the RP */
 
     QEMU_VM_CMD_AFTERLASTVALID
 };
@@ -97,6 +99,8 @@ void qemu_savevm_state_cancel(void);
 uint64_t qemu_savevm_state_pending(QEMUFile *f, uint64_t max_size);
 void qemu_savevm_command_send(QEMUFile *f, enum qemu_vm_cmd command,
                               uint16_t len, uint8_t *data);
+void qemu_savevm_send_reqack(QEMUFile *f, uint32_t value);
+void qemu_savevm_send_openrp(QEMUFile *f);
 int qemu_loadvm_state(QEMUFile *f);
 
 /* SLIRP */
diff --git a/savevm.c b/savevm.c
index 3cae292..793384a 100644
--- a/savevm.c
+++ b/savevm.c
@@ -611,6 +611,19 @@ void qemu_savevm_command_send(QEMUFile *f,
     qemu_fflush(f);
 }
 
+void qemu_savevm_send_reqack(QEMUFile *f, uint32_t value)
+{
+    uint32_t buf;
+
+    DPRINTF("send_reqack %d", value);
+    buf = cpu_to_be32(value);
+    qemu_savevm_command_send(f, QEMU_VM_CMD_REQACK, 4, (uint8_t *)&buf);
+}
+
+void qemu_savevm_send_openrp(QEMUFile *f)
+{
+    qemu_savevm_command_send(f, QEMU_VM_CMD_OPENRP, 0, NULL);
+}
 bool qemu_savevm_state_blocked(Error **errp)
 {
     SaveStateEntry *se;
@@ -900,20 +913,64 @@ static SaveStateEntry *find_se(const char *idstr, int instance_id)
     return NULL;
 }
 
+static int loadvm_process_command_simple_lencheck(const char *name,
+                                                  unsigned int actual,
+                                                  unsigned int expected)
+{
+    if (actual != expected) {
+        error_report("%s received with bad length - expecting %d, got %d",
+                     name, expected, actual);
+        return -1;
+    }
+
+    return 0;
+}
+
 /*
  * Process an incoming 'QEMU_VM_COMMAND'
  * negative return on error (will issue error message)
  */
 static int loadvm_process_command(QEMUFile *f)
 {
+    MigrationIncomingState *mis = migration_incoming_get_current();
     uint16_t com;
     uint16_t len;
+    uint32_t tmp32;
 
     com = qemu_get_be16(f);
     len = qemu_get_be16(f);
 
     /* fprintf(stderr,"loadvm_process_command: com=0x%x len=%d\n", com,len); */
     switch (com) {
+    case QEMU_VM_CMD_OPENRP:
+        if (loadvm_process_command_simple_lencheck("CMD_OPENRP", len, 0)) {
+            return -1;
+        }
+        if (mis->return_path) {
+            error_report("CMD_OPENRP called when RP already open");
+            /* Not really a problem, so don't give up */
+            return 0;
+        }
+        mis->return_path = qemu_file_get_return_path(f);
+        if (!mis->return_path) {
+            error_report("CMD_OPENRP failed - could not open return path");
+            return -1;
+        }
+        break;
+
+    case QEMU_VM_CMD_REQACK:
+        if (loadvm_process_command_simple_lencheck("CMD_REQACK", len, 4)) {
+            return -1;
+        }
+        tmp32 = qemu_get_be32(f);
+        DPRINTF("Received REQACK 0x%x", tmp32);
+        if (!mis->return_path) {
+            error_report("CMD_REQACK (0x%x) received with no open return path",
+                         tmp32);
+            return -1;
+        }
+        /* migrate_send_rp_ack(mis, tmp32); TODO: gets added later */
+        break;
 
     default:
         error_report("VM_COMMAND 0x%x unknown (len 0x%x)", com, len);
-- 
1.9.3