Existing 'migrate' QAPI design enforces transport mechanism, ip address
of destination interface and corresponding port number in the form
of a unified string 'uri' parameter for initiating a migration stream.
This scheme has a significant flaw in it - double encoding of existing
URIs to extract migration info.

The current patch maps QAPI uri design onto well defined MigrateChannel
struct. This modified QAPI helps in preventing multi-level uri
encodings ('uri' parameter is kept for backward compatibility).

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Suggested-by: Daniel P. Berrange <berrange@redhat.com>
Suggested-by: Manish Mishra <manish.mishra@nutanix.com>
Suggested-by: Aravind Retnakaran <aravind.retnakaran@nutanix.com>
Signed-off-by: Het Gala <het.gala@nutanix.com>
---
 qapi/migration.json | 129 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 127 insertions(+), 2 deletions(-)

diff --git a/qapi/migration.json b/qapi/migration.json
index c84fa10e86..261a6770e7 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -1449,12 +1449,106 @@
 ##
 { 'command': 'migrate-continue', 'data': {'state': 'MigrationStatus'} }
 
+##
+# @MigrateTransport:
+#
+# The supported communication transport mechanisms for migration
+#
+# @socket: Supported communication type between two devices for migration.
+#          Socket is able to cover all of 'tcp', 'unix', 'vsock' and
+#          'fd' already
+#
+# @exec: Supported communication type to redirect migration stream into file.
+#
+# @rdma: Supported communication type to redirect rdma type migration stream.
+#
+# Since 8.0
+##
+{ 'enum': 'MigrateTransport',
+  'data': ['socket', 'exec', 'rdma'] }
+
+##
+# @MigrateSocketAddr:
+#
+# To support different type of socket.
+#
+# Since 8.0
+##
+{ 'struct': 'MigrateSocketAddr',
+  'data': {'data': 'SocketAddress' } }
+
+##
+# @MigrateExecAddr:
+ #
+ # Since 8.0
+ ##
+{ 'struct': 'MigrateExecAddr',
+   'data': {'data': [ 'str' ] } }
+
+##
+# @MigrateRdmaAddr:
+#
+# Since 8.0
+##
+{ 'struct': 'MigrateRdmaAddr',
+   'data': {'data': 'InetSocketAddress' } }
+
+##
+# @MigrateAddress:
+#
+# The options available for communication transport mechanisms for migration
+#
+# Since 8.0
+##
+{ 'union': 'MigrateAddress',
+  'base': { 'transport' : 'MigrateTransport'},
+  'discriminator': 'transport',
+  'data': {
+    'socket': 'MigrateSocketAddr',
+    'exec': 'MigrateExecAddr',
+    'rdma': 'MigrateRdmaAddr' } }
+
+##
+# @MigrateChannelType:
+#
+# The supported options for migration channel type requests
+#
+# @main: Support request for main outbound migration control channel
+#
+# Since 8.0
+##
+{ 'enum': 'MigrateChannelType',
+  'data': [ 'main' ] }
+
+##
+# @MigrateChannel:
+#
+# Information regarding migration Channel-type for transferring packets,
+# source and corresponding destination interface for socket connection
+# and number of multifd channels over the interface.
+#
+# @channeltype: Name of Channel type for transfering packet information
+#
+# @addr: Information regarding migration parameters of destination interface
+#
+# Since 8.0
+##
+{ 'struct': 'MigrateChannel',
+  'data': {
+	'channeltype': 'MigrateChannelType',
+	'addr': 'MigrateAddress' } }
+
 ##
 # @migrate:
 #
 # Migrates the current running guest to another Virtual Machine.
 #
 # @uri: the Uniform Resource Identifier of the destination VM
+#       for migration thread
+#
+# @channel: Struct containing migration channel type, along with all
+#           the details of destination interface required for initiating
+#           a migration stream.
 #
 # @blk: do block migration (full disk copy)
 #
@@ -1479,15 +1573,46 @@
 # 3. The user Monitor's "detach" argument is invalid in QMP and should not
 #    be used
 #
+# 4. The uri argument should have the Uniform Resource Identifier of default
+#    destination VM. This connection will be bound to default network
+#
+# 5. The 'uri' and 'channel' arguments are mutually exclusive; exactly one
+#    of the two should be present.
+#
 # Example:
 #
 # -> { "execute": "migrate", "arguments": { "uri": "tcp:0:4446" } }
 # <- { "return": {} }
 #
+# -> { "execute": "migrate",
+#      "arguments": {
+#          "channel": { "channeltype": "main",
+#                        "addr": { "transport": "socket",
+#                                  "data": { "type": "inet",
+#                                            "host": "10.12.34.9",
+#                                            "port": "1050" } } } } }
+# <- { "return": {} }
+#
+# -> { "execute": "migrate",
+#      "arguments": {
+#          "channel": { "channeltype": "main",
+#                       "addr": { "transport": "exec",
+#                                 "data": [ "/bin/nc", "-U",
+#                                           "/some/sock" ] } } } }
+# <- { "return": {} }
+#
+# -> { "execute": "migrate",
+#      "arguments": {
+#          "channel": { "channeltype": "main",
+#                       "addr": { "transport": "rdma",
+#                                 "data": { "host": "10.12.34.9",
+#                                           "port": "1050" } } } } }
+# <- { "return": {} }
+#
 ##
 { 'command': 'migrate',
-  'data': {'uri': 'str', '*blk': 'bool', '*inc': 'bool',
-           '*detach': 'bool', '*resume': 'bool' } }
+  'data': {'*uri': 'str', '*channel': 'MigrateChannel', '*blk': 'bool',
+           '*inc': 'bool', '*detach': 'bool', '*resume': 'bool' } }
 
 ##
 # @migrate-incoming:
-- 
2.22.3

Just a quick one on naming before I forget:

Het Gala <het.gala@nutanix.com> writes:

> Existing 'migrate' QAPI design enforces transport mechanism, ip address
> of destination interface and corresponding port number in the form
> of a unified string 'uri' parameter for initiating a migration stream.
> This scheme has a significant flaw in it - double encoding of existing
> URIs to extract migration info.
>
> The current patch maps QAPI uri design onto well defined MigrateChannel
> struct. This modified QAPI helps in preventing multi-level uri
> encodings ('uri' parameter is kept for backward compatibility).
>
> Reviewed-by: Eric Blake <eblake@redhat.com>
> Reviewed-by: Markus Armbruster <armbru@redhat.com>
> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> Suggested-by: Daniel P. Berrange <berrange@redhat.com>
> Suggested-by: Manish Mishra <manish.mishra@nutanix.com>
> Suggested-by: Aravind Retnakaran <aravind.retnakaran@nutanix.com>
> Signed-off-by: Het Gala <het.gala@nutanix.com>
> ---
>  qapi/migration.json | 129 +++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 127 insertions(+), 2 deletions(-)
>
> diff --git a/qapi/migration.json b/qapi/migration.json
> index c84fa10e86..261a6770e7 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -1449,12 +1449,106 @@
>  ##
>  { 'command': 'migrate-continue', 'data': {'state': 'MigrationStatus'} }
>  
> +##
> +# @MigrateTransport:
> +#
> +# The supported communication transport mechanisms for migration
> +#
> +# @socket: Supported communication type between two devices for migration.
> +#          Socket is able to cover all of 'tcp', 'unix', 'vsock' and
> +#          'fd' already
> +#
> +# @exec: Supported communication type to redirect migration stream into file.
> +#
> +# @rdma: Supported communication type to redirect rdma type migration stream.
> +#
> +# Since 8.0
> +##
> +{ 'enum': 'MigrateTransport',
> +  'data': ['socket', 'exec', 'rdma'] }
> +
> +##
> +# @MigrateSocketAddr:
> +#
> +# To support different type of socket.
> +#
> +# Since 8.0
> +##
> +{ 'struct': 'MigrateSocketAddr',

We tend to avoid abbreviations in QAPI schema names.  For instance, it's
SocketAddress, not SocketAddr.  Please use Address, not Addr, for
consistency.

> +  'data': {'data': 'SocketAddress' } }
> +

[...]