migration: Enable TLS for preempt channel

This patch is based on the async preempt channel creation.  It continues
wiring up the new channel with TLS handshake to destionation when enabled.

Note that only the src QEMU needs such operation; the dest QEMU does not
need any change for TLS support due to the fact that all channels are
established synchronously there, so all the TLS magic is already properly
handled by migration_tls_channel_process_incoming().
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20220707185518.27529-1-peterx@redhat.com>
Signed-off-by: NDr. David Alan Gilbert <dgilbert@redhat.com>

migration/postcopy-ram.c

@@ -36,6 +36,7 @@
 #include "socket.h"
 #include "qemu-file.h"
 #include "yank_functions.h"
+#include "tls.h"
 
 /* Arbitrary limit on size of each discard command,
  * keeps them around ~200 bytes
@@ -1552,15 +1553,15 @@ bool postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file)
     return true;
 }
 
+/*
+ * Setup the postcopy preempt channel with the IOC.  If ERROR is specified,
+ * setup the error instead.  This helper will free the ERROR if specified.
+ */
 static void
-postcopy_preempt_send_channel_new(QIOTask *task, gpointer opaque)
+postcopy_preempt_send_channel_done(MigrationState *s,
+                                   QIOChannel *ioc, Error *local_err)
 {
-    MigrationState *s = opaque;
-    QIOChannel *ioc = QIO_CHANNEL(qio_task_get_source(task));
-    Error *local_err = NULL;
-
-    if (qio_task_propagate_error(task, &local_err)) {
-        /* Something wrong happened.. */
+    if (local_err) {
         migrate_set_error(s, local_err);
         error_free(local_err);
     } else {
@@ -1574,7 +1575,47 @@ postcopy_preempt_send_channel_new(QIOTask *task, gpointer opaque)
      * postcopy_qemufile_src to know whether it failed or not.
      */
     qemu_sem_post(&s->postcopy_qemufile_src_sem);
-    object_unref(OBJECT(ioc));
+}
+
+static void
+postcopy_preempt_tls_handshake(QIOTask *task, gpointer opaque)
+{
+    g_autoptr(QIOChannel) ioc = QIO_CHANNEL(qio_task_get_source(task));
+    MigrationState *s = opaque;
+    Error *local_err = NULL;
+
+    qio_task_propagate_error(task, &local_err);
+    postcopy_preempt_send_channel_done(s, ioc, local_err);
+}
+
+static void
+postcopy_preempt_send_channel_new(QIOTask *task, gpointer opaque)
+{
+    g_autoptr(QIOChannel) ioc = QIO_CHANNEL(qio_task_get_source(task));
+    MigrationState *s = opaque;
+    QIOChannelTLS *tioc;
+    Error *local_err = NULL;
+
+    if (qio_task_propagate_error(task, &local_err)) {
+        goto out;
+    }
+
+    if (migrate_channel_requires_tls_upgrade(ioc)) {
+        tioc = migration_tls_client_create(s, ioc, s->hostname, &local_err);
+        if (!tioc) {
+            goto out;
+        }
+        trace_postcopy_preempt_tls_handshake();
+        qio_channel_set_name(QIO_CHANNEL(tioc), "migration-tls-preempt");
+        qio_channel_tls_handshake(tioc, postcopy_preempt_tls_handshake,
+                                  s, NULL, NULL);
+        /* Setup the channel until TLS handshake finished */
+        return;
+    }
+
+out:
+    /* This handles both good and error cases */
+    postcopy_preempt_send_channel_done(s, ioc, local_err);
 }
 
 /* Returns 0 if channel established, -1 for error. */

migration/trace-events

@@ -287,6 +287,7 @@ postcopy_request_shared_page(const char *sharer, const char *rb, uint64_t rb_off
 postcopy_request_shared_page_present(const char *sharer, const char *rb, uint64_t rb_offset) "%s already %s offset 0x%"PRIx64
 postcopy_wake_shared(uint64_t client_addr, const char *rb) "at 0x%"PRIx64" in %s"
 postcopy_page_req_del(void *addr, int count) "resolved page req %p total %d"
+postcopy_preempt_tls_handshake(void) ""
 postcopy_preempt_new_channel(void) ""
 postcopy_preempt_thread_entry(void) ""
 postcopy_preempt_thread_exit(void) ""