sev/i386: qmp: add query-sev-launch-measure command

The command can be used by libvirt to retrieve the measurement of SEV guest.
This measurement is a signature of the memory contents that was encrypted
through the LAUNCH_UPDATE_DATA.

Cc: "Daniel P. Berrangé" <berrange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

monitor.c

@@ -984,6 +984,7 @@ static void qmp_unregister_commands_hack(void)
 #ifndef TARGET_I386
     qmp_unregister_command(&qmp_commands, "rtc-reset-reinjection");
     qmp_unregister_command(&qmp_commands, "query-sev");
+    qmp_unregister_command(&qmp_commands, "query-sev-launch-measure");
 #endif
 #ifndef TARGET_S390X
     qmp_unregister_command(&qmp_commands, "dump-skeys");
@@ -4110,6 +4111,12 @@ SevInfo *qmp_query_sev(Error **errp)
     error_setg(errp, QERR_FEATURE_DISABLED, "query-sev");
     return NULL;
 }
+
+SevLaunchMeasureInfo *qmp_query_sev_launch_measure(Error **errp)
+{
+    error_setg(errp, QERR_FEATURE_DISABLED, "query-sev-launch-measure");
+    return NULL;
+}
 #endif
 
 #ifndef TARGET_S390X

qapi/misc.json

@@ -3293,3 +3293,32 @@
 #
 ##
 { 'command': 'query-sev', 'returns': 'SevInfo' }
+
+##
+# @SevLaunchMeasureInfo:
+#
+# SEV Guest Launch measurement information
+#
+# @data: the measurement value encoded in base64
+#
+# Since: 2.12
+#
+##
+{ 'struct': 'SevLaunchMeasureInfo', 'data': {'data': 'str'} }
+
+##
+# @query-sev-launch-measure:
+#
+# Query the SEV guest launch information.
+#
+# Returns: The @SevLaunchMeasureInfo for the guest
+#
+# Since: 2.12
+#
+# Example:
+#
+# -> { "execute": "query-sev-launch-measure" }
+# <- { "return": { "data": "4l8LXeNlSPUDlXPJG5966/8%YZ" } }
+#
+##
+{ 'command': 'query-sev-launch-measure', 'returns': 'SevLaunchMeasureInfo' }

target/i386/monitor.c

@@ -697,3 +697,20 @@ void hmp_info_sev(Monitor *mon, const QDict *qdict)
         monitor_printf(mon, "SEV is not enabled\n");
     }
 }
+
+SevLaunchMeasureInfo *qmp_query_sev_launch_measure(Error **errp)
+{
+    char *data;
+    SevLaunchMeasureInfo *info;
+
+    data = sev_get_launch_measurement();
+    if (!data) {
+        error_setg(errp, "Measurement is not available");
+        return NULL;
+    }
+
+    info = g_malloc0(sizeof(*info));
+    info->data = data;
+
+    return info;
+}

tests/qmp-test.c

@@ -204,6 +204,8 @@ static bool query_is_blacklisted(const char *cmd)
         "query-gic-capabilities", /* arm */
         /* Success depends on target-specific build configuration: */
         "query-pci",              /* CONFIG_PCI */
+        /* Success depends on launching SEV guest */
+        "query-sev-launch-measure",
         /* Success depends on Host or Hypervisor SEV support */
         "query-sev",
         NULL