conf: Add rng backend model builtin

The 'builtin' rng backend model can be used as following:
  <rng model='virtio'>
    <backend model='builtin'/>
  </rng>

Signed-off-by: Han Han <hhan@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

docs/formatdomain.html.in

@@ -8259,6 +8259,8 @@ qemu-kvm -net nic,model=? /dev/null
       <source mode='bind' service='1234'/>
       <source mode='connect' host='1.2.3.4' service='1234'/>
     </backend>
+    <!-- OR -->
+    <backend model='builtin'/>
   </rng>
 </devices>
 ...
@@ -8323,6 +8325,14 @@ qemu-kvm -net nic,model=? /dev/null
               for more information.
             </p>
           </dd>
+          <dt><code>builtin</code></dt>
+          <dd>
+            <p>
+              This backend uses qemu builtin random generator, which uses
+              <code>getrandom()</code> syscall as the source of entropy.
+              (<span class="since">Since 6.1.0 and QEMU 4.2</span>)
+            </p>
+          </dd>
         </dl>
       </dd>
       <dt><code>driver</code></dt>

docs/formatdomaincaps.html.in

@@ -481,6 +481,7 @@
       <enum name='backendModel'>
         <value>random</value>
         <value>egd</value>
+        <value>builtin</value>
       </enum>
     </rng>
     ...

docs/schemas/domaincommon.rng

@@ -5683,6 +5683,12 @@
           <ref name="qemucdevSrcType"/>
           <ref name="qemucdevSrcDef"/>
         </group>
+        <group>
+          <attribute name="model">
+            <value>builtin</value>
+          </attribute>
+          <empty/>
+        </group>
       </choice>
     </element>
   </define>

src/conf/domain_audit.c

@@ -227,6 +227,7 @@ virDomainAuditRNG(virDomainObjPtr vm,
             newsrcpath = virDomainChrSourceDefGetPath(newDef->source.chardev);
             break;
 
+        case VIR_DOMAIN_RNG_BACKEND_BUILTIN:
         case VIR_DOMAIN_RNG_BACKEND_LAST:
             break;
         }
@@ -242,6 +243,7 @@ virDomainAuditRNG(virDomainObjPtr vm,
             oldsrcpath = virDomainChrSourceDefGetPath(oldDef->source.chardev);
             break;
 
+        case VIR_DOMAIN_RNG_BACKEND_BUILTIN:
         case VIR_DOMAIN_RNG_BACKEND_LAST:
             break;
         }

src/conf/domain_conf.c

@@ -1113,6 +1113,7 @@ VIR_ENUM_IMPL(virDomainRNGBackend,
               VIR_DOMAIN_RNG_BACKEND_LAST,
               "random",
               "egd",
+              "builtin",
 );
 
 VIR_ENUM_IMPL(virDomainTPMModel,
@@ -14792,6 +14793,7 @@ virDomainRNGDefParseXML(virDomainXMLOptionPtr xmlopt,
             goto error;
         break;
 
+    case VIR_DOMAIN_RNG_BACKEND_BUILTIN:
     case VIR_DOMAIN_RNG_BACKEND_LAST:
         break;
     }
@@ -17851,6 +17853,7 @@ virDomainRNGFind(virDomainDefPtr def,
                 continue;
             break;
 
+        case VIR_DOMAIN_RNG_BACKEND_BUILTIN:
         case VIR_DOMAIN_RNG_BACKEND_LAST:
             break;
         }
@@ -26531,6 +26534,11 @@ virDomainRNGDefFormat(virBufferPtr buf,
             return -1;
         virBufferAdjustIndent(buf, -2);
         virBufferAddLit(buf, "</backend>\n");
+        break;
+
+    case VIR_DOMAIN_RNG_BACKEND_BUILTIN:
+        virBufferAddLit(buf, "/>\n");
+        break;
 
     case VIR_DOMAIN_RNG_BACKEND_LAST:
         break;
@@ -26562,6 +26570,7 @@ virDomainRNGDefFree(virDomainRNGDefPtr def)
     case VIR_DOMAIN_RNG_BACKEND_EGD:
         virObjectUnref(def->source.chardev);
         break;
+    case VIR_DOMAIN_RNG_BACKEND_BUILTIN:
     case VIR_DOMAIN_RNG_BACKEND_LAST:
         break;
     }

src/conf/domain_conf.h

@@ -2106,6 +2106,7 @@ typedef enum {
 typedef enum {
     VIR_DOMAIN_RNG_BACKEND_RANDOM,
     VIR_DOMAIN_RNG_BACKEND_EGD,
+    VIR_DOMAIN_RNG_BACKEND_BUILTIN,
 
     VIR_DOMAIN_RNG_BACKEND_LAST
 } virDomainRNGBackend;

src/qemu/qemu_command.c

@@ -5594,6 +5594,12 @@ qemuBuildRNGBackendChrdevStr(virLogManagerPtr logManager,
                                             rng->info.alias, qemuCaps,
                                             cdevflags)))
             return -1;
+        break;
+
+    case VIR_DOMAIN_RNG_BACKEND_BUILTIN:
+        virReportUnsupportedError();
+        return -1;
+        break;
     }
 
     return 0;
@@ -5644,6 +5650,10 @@ qemuBuildRNGBackendProps(virDomainRNGDefPtr rng,
 
         break;
 
+    case VIR_DOMAIN_RNG_BACKEND_BUILTIN:
+        virReportUnsupportedError();
+        return -1;
+
     case VIR_DOMAIN_RNG_BACKEND_LAST:
         virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
                        _("unknown rng-random backend"));

src/qemu/qemu_domain.c

@@ -14807,8 +14807,10 @@ qemuDomainSetupRNG(virQEMUDriverConfigPtr cfg G_GNUC_UNUSED,
     case VIR_DOMAIN_RNG_BACKEND_RANDOM:
         if (qemuDomainCreateDevice(rng->source.file, data, false) < 0)
             return -1;
+        break;
 
     case VIR_DOMAIN_RNG_BACKEND_EGD:
+    case VIR_DOMAIN_RNG_BACKEND_BUILTIN:
     case VIR_DOMAIN_RNG_BACKEND_LAST:
         /* nada */
         break;
@@ -15788,6 +15790,7 @@ qemuDomainNamespaceSetupRNG(virDomainObjPtr vm,
         break;
 
     case VIR_DOMAIN_RNG_BACKEND_EGD:
+    case VIR_DOMAIN_RNG_BACKEND_BUILTIN:
     case VIR_DOMAIN_RNG_BACKEND_LAST:
         break;
     }
@@ -15811,6 +15814,7 @@ qemuDomainNamespaceTeardownRNG(virDomainObjPtr vm,
         break;
 
     case VIR_DOMAIN_RNG_BACKEND_EGD:
+    case VIR_DOMAIN_RNG_BACKEND_BUILTIN:
     case VIR_DOMAIN_RNG_BACKEND_LAST:
         break;
     }