slirp: use libslirp migration code

slirp migration code uses QEMU vmstate so far, when building WITH_QEMU.

Introduce slirp_state_{load,save,version}() functions to move the
state saving handling to libslirp side.

So far, the bitstream compatibility should remain equal with current
QEMU, as this is effectively using the same code, with the same format
etc. When libslirp is made standalone, we will need some mechanism to
ensure bitstream compatibility regardless of the libslirp version
installed. See the FIXME note in the code.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20190212162524.31504-3-marcandre.lureau@redhat.com>
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>

1 files changed, 55 insertions, 0 deletions

diff --git a/net/slirp.c b/net/slirp.c
index a8fd9e6..059b2d9 100644
--- a/net/slirp.c
+++ b/net/slirp.c
@@ -44,6 +44,8 @@
 #include "qapi/error.h"
 #include "qapi/qmp/qdict.h"
 #include "util.h"
+#include "migration/register.h"
+#include "migration/qemu-file-types.h"
 
 static int get_str_sep(char *buf, int buf_size, const char **pp, int sep)
 {
@@ -146,6 +148,7 @@ static void net_slirp_cleanup(NetClientState *nc)
 
     g_slist_free_full(s->fwd, slirp_free_fwd);
     main_loop_poll_remove_notifier(&s->poll_notifier);
+    unregister_savevm(NULL, "slirp", s->slirp);
     slirp_cleanup(s->slirp);
     if (s->exit_notifier.notify) {
         qemu_remove_exit_notifier(&s->exit_notifier);
@@ -303,6 +306,46 @@ static void net_slirp_poll_notify(Notifier *notifier, void *data)
     }
 }
 
+static ssize_t
+net_slirp_stream_read(void *buf, size_t size, void *opaque)
+{
+    QEMUFile *f = opaque;
+
+    return qemu_get_buffer(f, buf, size);
+}
+
+static ssize_t
+net_slirp_stream_write(const void *buf, size_t size, void *opaque)
+{
+    QEMUFile *f = opaque;
+
+    qemu_put_buffer(f, buf, size);
+    if (qemu_file_get_error(f)) {
+        return -1;
+    }
+
+    return size;
+}
+
+static int net_slirp_state_load(QEMUFile *f, void *opaque, int version_id)
+{
+    Slirp *slirp = opaque;
+
+    return slirp_state_load(slirp, version_id, net_slirp_stream_read, f);
+}
+
+static void net_slirp_state_save(QEMUFile *f, void *opaque)
+{
+    Slirp *slirp = opaque;
+
+    slirp_state_save(slirp, net_slirp_stream_write, f);
+}
+
+static SaveVMHandlers savevm_slirp_state = {
+    .save_state = net_slirp_state_save,
+    .load_state = net_slirp_state_load,
+};
+
 static int net_slirp_init(NetClientState *peer, const char *model,
                           const char *name, int restricted,
                           bool ipv4, const char *vnetwork, const char *vhost,
@@ -523,6 +566,18 @@ static int net_slirp_init(NetClientState *peer, const char *model,
                           &slirp_cb, s);
     QTAILQ_INSERT_TAIL(&slirp_stacks, s, entry);
 
+    /*
+     * Make sure the current bitstream version of slirp is 4, to avoid
+     * QEMU migration incompatibilities, if upstream slirp bumped the
+     * version.
+     *
+     * FIXME: use bitfields of features? teach libslirp to save with
+     * specific version?
+     */
+    g_assert(slirp_state_version() == 4);
+    register_savevm_live(NULL, "slirp", 0, slirp_state_version(),
+                         &savevm_slirp_state, s->slirp);
+
     s->poll_notifier.notify = net_slirp_poll_notify;
     main_loop_poll_add_notifier(&s->poll_notifier);