[PATCH v2 2/2] tpm: Return QMP error when TPM is disabled in build

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

When the management layer queries a binary built using --disable-tpm
for TPM devices, it gets confused by getting empty responses:

  { "execute": "query-tpm" }
  {
      "return": [
      ]
  }
  { "execute": "query-tpm-types" }
  {
      "return": [
      ]
  }
  { "execute": "query-tpm-models" }
  {
      "return": [
      ]
  }

To make it clearer by returning an error:
- Make the TPM QAPI schema conditional
- Adapt the HMP command
- Remove stubs which became unnecessary

The management layer now gets a 'CommandNotFound' error:

  { "execute": "query-tpm" }
  {
      "error": {
          "class": "CommandNotFound",
          "desc": "The command query-tpm has not been found"
      }
  }

Suggested-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 qapi/tpm.json      |  9 ++++++---
 monitor/hmp-cmds.c |  4 ++++
 stubs/tpm.c        | 16 ----------------
 3 files changed, 10 insertions(+), 19 deletions(-)

diff --git a/qapi/tpm.json b/qapi/tpm.json
index 6a10c9ed8d2..09332e6f996 100644
--- a/qapi/tpm.json
+++ b/qapi/tpm.json
@@ -33,7 +33,8 @@
 # <- { "return": [ "tpm-tis", "tpm-crb", "tpm-spapr" ] }
 #
 ##
-{ 'command': 'query-tpm-models', 'returns': ['TpmModel'] }
+{ 'command': 'query-tpm-models', 'returns': ['TpmModel'],
+  'if': 'defined(CONFIG_TPM)' }
 
 ##
 # @TpmType:
@@ -63,7 +64,8 @@
 # <- { "return": [ "passthrough", "emulator" ] }
 #
 ##
-{ 'command': 'query-tpm-types', 'returns': ['TpmType'] }
+{ 'command': 'query-tpm-types', 'returns': ['TpmType'],
+  'if': 'defined(CONFIG_TPM)' }
 
 ##
 # @TPMPassthroughOptions:
@@ -152,4 +154,5 @@
 #    }
 #
 ##
-{ 'command': 'query-tpm', 'returns': ['TPMInfo'] }
+{ 'command': 'query-tpm', 'returns': ['TPMInfo'],
+  'if': 'defined(CONFIG_TPM)' }
diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
index d10ee141109..f6cadede40f 100644
--- a/monitor/hmp-cmds.c
+++ b/monitor/hmp-cmds.c
@@ -901,6 +901,9 @@ void hmp_info_pci(Monitor *mon, const QDict *qdict)
 
 void hmp_info_tpm(Monitor *mon, const QDict *qdict)
 {
+#ifndef CONFIG_TPM
+    monitor_printf(mon, "TPM device not supported\n");
+#else
     TPMInfoList *info_list, *info;
     Error *err = NULL;
     unsigned int c = 0;
@@ -946,6 +949,7 @@ void hmp_info_tpm(Monitor *mon, const QDict *qdict)
         c++;
     }
     qapi_free_TPMInfoList(info_list);
+#endif /* CONFIG_TPM */
 }
 
 void hmp_quit(Monitor *mon, const QDict *qdict)
diff --git a/stubs/tpm.c b/stubs/tpm.c
index 9bded191d9d..b1dc6370a5e 100644
--- a/stubs/tpm.c
+++ b/stubs/tpm.c
@@ -6,7 +6,6 @@
  */
 
 #include "qemu/osdep.h"
-#include "qapi/qapi-commands-tpm.h"
 #include "sysemu/tpm.h"
 #include "hw/acpi/tpm.h"
 
@@ -19,21 +18,6 @@ void tpm_cleanup(void)
 {
 }
 
-TPMInfoList *qmp_query_tpm(Error **errp)
-{
-    return NULL;
-}
-
-TpmTypeList *qmp_query_tpm_types(Error **errp)
-{
-    return NULL;
-}
-
-TpmModelList *qmp_query_tpm_models(Error **errp)
-{
-    return NULL;
-}
-
 void tpm_build_ppi_acpi(TPMIf *tpm, Aml *dev)
 {
 }
-- 
2.31.1