domcaps: Introduce TPM backendVersion

We accept TPM version in the domain XML. However, supported
version depends on the host (swtpm_setup binary) and thus it may
be tricky for users (or mgmt applications) chose a version.
Introduce machinery for reporting supported version in domain
capabilities.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>

docs/formatdomaincaps.rst

@@ -513,6 +513,10 @@ TPM device capabilities are exposed under the ``tpm`` element. For instance:
           <value>passthrough</value>
           <value>emulator</value>
         </enum>
+        <enum name='backendVersion'>
+          <value>1.2</value>
+          <value>2.0</value>
+        </enum>
       </tpm>
       ...
     </devices>
@@ -522,6 +526,8 @@ TPM device capabilities are exposed under the ``tpm`` element. For instance:
    Options for the ``model`` attribute of the ``<tpm/>`` element.
 ``backendModel``
    Options for the ``type`` attribute of the ``<tpm><backend/>`` element.
+``backendVersion``
+   Options for the ``version`` attribute of the ``<tpm><backend/>`` element.
 
 Features
 ~~~~~~~~

src/conf/domain_capabilities.c

@@ -539,6 +539,7 @@ virDomainCapsDeviceTPMFormat(virBuffer *buf,
 
     ENUM_PROCESS(tpm, model, virDomainTPMModelTypeToString);
     ENUM_PROCESS(tpm, backendModel, virDomainTPMBackendTypeToString);
+    ENUM_PROCESS(tpm, backendVersion, virDomainTPMVersionTypeToString);
 
     FORMAT_EPILOGUE(tpm);
 }

src/conf/domain_capabilities.h

@@ -127,6 +127,7 @@ struct _virDomainCapsDeviceTPM {
     virTristateBool supported;
     virDomainCapsEnum model;   /* virDomainTPMModel */
     virDomainCapsEnum backendModel;   /* virDomainTPMBackendType */
+    virDomainCapsEnum backendVersion; /* virDomainTPMVersion */
 };
 
 STATIC_ASSERT_ENUM(VIR_DOMAIN_FS_DRIVER_TYPE_LAST);