qapi: make the vcpu parameters deprecated for 8.1

I don't think I can remove the parameters directly but certainly mark
them as deprecated.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 20230526165401.574474-7-alex.bennee@linaro.org
Message-Id: <20230524133952.3971948-6-alex.bennee@linaro.org>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

docs/about/deprecated.rst

@@ -226,6 +226,13 @@ QEMU Machine Protocol (QMP) events
 
 Use the more generic event ``DEVICE_UNPLUG_GUEST_ERROR`` instead.
 
+``vcpu`` trace events (since 8.1)
+'''''''''''''''''''''''''''''''''
+
+The ability to instrument QEMU helper functions with vCPU-aware trace
+points was removed in 7.0. However QMP still exposed the vcpu
+parameter. This argument has now been deprecated and the remaining
+remaining trace points that used it are selected just by name.
 
 Human Monitor Protocol (HMP) commands
 -------------------------------------

qapi/trace.json

@@ -37,13 +37,14 @@
 #
 # @vcpu: Whether this is a per-vCPU event (since 2.7).
 #
-# An event is per-vCPU if it has the "vcpu" property in the
-# "trace-events" files.
+# Features:
+# @deprecated: Member @vcpu is deprecated, and always ignored.
 #
 # Since: 2.2
 ##
 { 'struct': 'TraceEventInfo',
-  'data': {'name': 'str', 'state': 'TraceEventState', 'vcpu': 'bool'} }
+  'data': {'name': 'str', 'state': 'TraceEventState',
+           'vcpu': { 'type': 'bool', 'features': ['deprecated'] } } }
 
 ##
 # @trace-event-get-state:
@@ -52,19 +53,15 @@
 #
 # @name: Event name pattern (case-sensitive glob).
 #
-# @vcpu: The vCPU to query (any by default; since 2.7).
+# @vcpu: The vCPU to query (since 2.7).
 #
-# Returns: a list of @TraceEventInfo for the matching events
-#
-# An event is returned if:
+# Features:
+# @deprecated: Member @vcpu is deprecated, and always ignored.
 #
-# - its name matches the @name pattern, and
-# - if @vcpu is given, the event has the "vcpu" property.
+# Returns: a list of @TraceEventInfo for the matching events
 #
-# Therefore, if @vcpu is given, the operation will only match per-vCPU
-# events, returning their state on the specified vCPU. Special case:
-# if @name is an exact match, @vcpu is given and the event does not
-# have the "vcpu" property, an error is returned.
+# An event is returned if its name matches the @name pattern
+# (There are no longer any per-vCPU events).
 #
 # Since: 2.2
 #
@@ -75,7 +72,8 @@
 # <- { "return": [ { "name": "qemu_memalign", "state": "disabled", "vcpu": false } ] }
 ##
 { 'command': 'trace-event-get-state',
-  'data': {'name': 'str', '*vcpu': 'int'},
+  'data': {'name': 'str',
+           '*vcpu': {'type': 'int', 'features': ['deprecated'] } },
   'returns': ['TraceEventInfo'] }
 
 ##
@@ -91,15 +89,11 @@
 #
 # @vcpu: The vCPU to act upon (all by default; since 2.7).
 #
-# An event's state is modified if:
-#
-# - its name matches the @name pattern, and
-# - if @vcpu is given, the event has the "vcpu" property.
+# Features:
+# @deprecated: Member @vcpu is deprecated, and always ignored.
 #
-# Therefore, if @vcpu is given, the operation will only match per-vCPU
-# events, setting their state on the specified vCPU. Special case: if
-# @name is an exact match, @vcpu is given and the event does not have
-# the "vcpu" property, an error is returned.
+# An event is enabled if its name matches the @name pattern
+# (There are no longer any per-vCPU events).
 #
 # Since: 2.2
 #
@@ -111,4 +105,4 @@
 ##
 { 'command': 'trace-event-set-state',
   'data': {'name': 'str', 'enable': 'bool', '*ignore-unavailable': 'bool',
-           '*vcpu': 'int'} }
+           '*vcpu': {'type': 'int', 'features': ['deprecated'] } } }