ui/vdagent: core infrastructure

The vdagent protocol allows the guest agent (spice-vdagent) and the
spice client exchange messages to implement features which require
guest cooperation, for example clipboard support.

This is a qemu implementation of the spice client side.  This allows
the spice guest agent talk to qemu directly when not using the spice
protocol.

usage: qemu \
  -chardev qemu-vdagent,id=vdagent \
  -device virtserialport,chardev=vdagent,name=com.redhat.spice.0

This patch adds just the protocol basics: initial handshake and
capability negotiation.  The following patches will add actual
functionality and also add fields to the initially empty
ChardevVDAgent qapi struct.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20210519053940.1888907-1-kraxel@redhat.com
Message-Id: <20210519053940.1888907-5-kraxel@redhat.com>

qapi/char.json

@@ -390,12 +390,25 @@
   'data': { '*size': 'int' },
   'base': 'ChardevCommon' }
 
+##
+# @ChardevQemuVDAgent:
+#
+# Configuration info for qemu vdagent implementation.
+#
+# Since: 6.1
+#
+##
+{ 'struct': 'ChardevQemuVDAgent',
+  'data': { },
+  'base': 'ChardevCommon',
+  'if': 'defined(CONFIG_SPICE_PROTOCOL)' }
+
 ##
 # @ChardevBackend:
 #
 # Configuration info for the new chardev backend.
 #
-# Since: 1.4 (testdev since 2.2, wctablet since 2.9)
+# Since: 1.4 (testdev since 2.2, wctablet since 2.9, vdagent since 6.1)
 ##
 { 'union': 'ChardevBackend',
   'data': { 'file': 'ChardevFile',
@@ -417,6 +430,8 @@
                           'if': 'defined(CONFIG_SPICE)' },
             'spiceport': { 'type': 'ChardevSpicePort',
                            'if': 'defined(CONFIG_SPICE)' },
+            'qemu-vdagent': { 'type': 'ChardevQemuVDAgent',
+                              'if': 'defined(CONFIG_SPICE_PROTOCOL)' },
             'vc': 'ChardevVC',
             'ringbuf': 'ChardevRingbuf',
             # next one is just for compatibility

ui/meson.build

@@ -14,6 +14,7 @@ softmmu_ss.add(files(
   'qemu-pixman.c',
 ))
 softmmu_ss.add([spice_headers, files('spice-module.c')])
+softmmu_ss.add(when: spice_protocol, if_true: files('vdagent.c'))
 
 softmmu_ss.add(when: 'CONFIG_LINUX', if_true: files('input-linux.c'))
 softmmu_ss.add(when: cocoa, if_true: files('cocoa.m'))

ui/trace-events

@@ -124,3 +124,11 @@ xkeymap_extension(const char *name) "extension '%s'"
 xkeymap_vendor(const char *name) "vendor '%s'"
 xkeymap_keycodes(const char *name) "keycodes '%s'"
 xkeymap_keymap(const char *name) "keymap '%s'"
+
+# vdagent.c
+vdagent_open(void) ""
+vdagent_close(void) ""
+vdagent_send(const char *name) "msg %s"
+vdagent_recv_chunk(uint32_t size) "size %d"
+vdagent_recv_msg(const char *name, uint32_t size) "msg %s, size %d"
+vdagent_peer_cap(const char *name) "cap %s"