[RFC,23/28] qmp: add QMP interface "query-cpu-model-expansion"

diff --git a/include/sysemu/arch_init.h b/include/sysemu/arch_init.h
index d690dfa..37b2e86 100644
--- a/include/sysemu/arch_init.h
+++ b/include/sysemu/arch_init.h
@@ -35,5 +35,8 @@  int kvm_available(void);
 int xen_available(void);
 
 CpuDefinitionInfoList *arch_query_cpu_definitions(Error **errp);
+CpuModelExpansionInfo *arch_query_cpu_model_expansion(CpuModelExpansionType type,
+                                                      CpuModelInfo *mode,
+                                                      Error **errp);
 
 #endif
diff --git a/qapi-schema.json b/qapi-schema.json
index 0964eec..5b72dc0 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -3026,6 +3026,87 @@ 
 ##
 { 'command': 'query-cpu-definitions', 'returns': ['CpuDefinitionInfo'] }
 
+##
+# @CpuModelInfo:
+#
+# Virtual CPU model.
+#
+# A CPU model consists of the name of a CPU definition, to which
+# delta changes are applied (e.g. features added/removed). Most magic values
+# that an architecture might require should be hidden behind the name.
+# However, if required, architectures can expose relevant properties.
+#
+# @name: the name of the CPU definition the model is based on
+# @props: #optional a dictionary of properties to be applied
+#
+# Since: 2.7.0
+##
+{ 'struct': 'CpuModelInfo',
+  'data': { 'name': 'str',
+            '*props': 'any' } }
+
+##
+# @CpuModelExpansionType
+#
+# An enumeration of CPU model expansion types.
+#
+# @stable: Expand to a stable CPU model, creating a migration-safe
+#          representation with only delta changes.
+#
+# @migratable: Expand all migratable properties, hiding unmigratable
+#              properties.
+#
+# @full: Expand all properties, including unmigratable ones.
+#
+# Since: 2.7.0
+##
+{ 'enum': 'CpuModelExpansionType',
+  'data': [ 'stable', 'migratable', 'full' ] }
+
+
+##
+# @CpuModelExpansionInfo
+#
+# The result of a cpu model expansion.
+#
+# @model: the expanded CpuModelInfo.
+#
+# Since: 2.7.0
+##
+{ 'struct': 'CpuModelExpansionInfo',
+  'data': { 'model': 'CpuModelInfo' } }
+
+
+##
+# @query-cpu-model-expansion:
+#
+# Expands the given CPU model to the requested detail level.
+# For "stable", a migration-safe representation is created, which will look
+# the same on all QEMU versions and only contains delta changes. "migratable"
+# and "full" will expose properties in a more detailed way. Not all types
+# might be supported for an architecture.
+#
+# Expanding CPU models is in general independant of the accelerator, except
+# for models like "host" that explicitly rely on an accelerator and can
+# vary in different configurations. On certain architectures, the result may
+# rely on the QEMU machine.
+#
+# This interface can therefore also be used to query the "host" capabilities
+# on supporting architectures.
+#
+# Returns: a CpuModelExpansionInfo. Returns an error if CPU models are not
+#          supported, if the model cannot be expanded, if the model contains
+#          an unknown cpu definition name, unknown properties or properties
+#          with a wrong type. Also returns an error if an expansion type is
+#          not supported.
+#
+# Since: 2.7.0
+##
+{ 'command': 'query-cpu-model-expansion',
+  'data': { 'type': 'CpuModelExpansionType',
+            'model': 'CpuModelInfo' },
+  'returns': 'CpuModelExpansionInfo' }
+
 # @AddfdInfo:
 #
 # Information about a file descriptor that was added to an fd set.
diff --git a/qmp-commands.hx b/qmp-commands.hx
index b444c20..b279fc5 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -3930,6 +3930,12 @@  EQMP
     },
 
     {
+        .name       = "query-cpu-model-expansion",
+        .args_type  = "model:q",
+        .mhandler.cmd_new = qmp_marshal_query_cpu_model_expansion,
+    },
+
+    {
         .name       = "query-target",
         .args_type  = "",
         .mhandler.cmd_new = qmp_marshal_query_target,
diff --git a/qmp.c b/qmp.c
index 7df6543..c54f0a0 100644
--- a/qmp.c
+++ b/qmp.c
@@ -607,6 +607,13 @@  CpuDefinitionInfoList *qmp_query_cpu_definitions(Error **errp)
     return arch_query_cpu_definitions(errp);
 }
 
+CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type,
+                                                     CpuModelInfo *model,
+                                                     Error **errp)
+{
+    return arch_query_cpu_model_expansion(type, model, errp);
+}
+
 void qmp_add_client(const char *protocol, const char *fdname,
                     bool has_skipauth, bool skipauth, bool has_tls, bool tls,
                     Error **errp)
diff --git a/stubs/Makefile.objs b/stubs/Makefile.objs
index 4b258a6..83915f5 100644
--- a/stubs/Makefile.objs
+++ b/stubs/Makefile.objs
@@ -1,4 +1,5 @@ 
 stub-obj-y += arch-query-cpu-def.o
+stub-obj-y += arch-query-cpu-model-expansion.o
 stub-obj-y += bdrv-next-monitor-owned.o
 stub-obj-y += blk-commit-all.o
 stub-obj-y += blockdev-close-all-bdrv-states.o
diff --git a/stubs/arch-query-cpu-model-expansion.c b/stubs/arch-query-cpu-model-expansion.c
new file mode 100644
index 0000000..ae7cf55
--- /dev/null
+++ b/stubs/arch-query-cpu-model-expansion.c
@@ -0,0 +1,12 @@ 
+#include "qemu/osdep.h"
+#include "qemu-common.h"
+#include "sysemu/arch_init.h"
+#include "qapi/qmp/qerror.h"
+
+CpuModelExpansionInfo *arch_query_cpu_model_expansion(CpuModelExpansionType type,
+                                                      CpuModelInfo *mode,
+                                                      Error **errp)
+{
+    error_setg(errp, QERR_UNSUPPORTED);
+    return NULL;
+}