conf: add <ioapic driver> to <features>

Add a new <ioapic> element with a driver attribute.

Possible values are qemu and kvm. With 'qemu', the I/O
APIC can be put in the userspace even for KVM domains.

https://bugzilla.redhat.com/show_bug.cgi?id=1427005

docs/formatdomain.html.in

@@ -1678,6 +1678,7 @@
   </kvm>
   <pvspinlock state='on'/>
   <gic version='2'/>
+  <ioapic driver='qemu'/>
 
 </features>
 ...</pre>
@@ -1839,6 +1840,14 @@
           for hypervisor to decide.
           <span class="since">Since 2.1.0</span>
       </dd>
+      <dt><code>ioapic</code></dt>
+      <dd>Tune the I/O APIC. Possible values for the
+          <code>driver</code> attribute are:
+          <code>kvm</code> (default for KVM domains)
+          and <code>qemu</code> which puts I/O APIC in userspace
+          which is also known as a split I/O APIC mode.
+          <span class="since">Since 3.4.0</span> (QEMU/KVM only)
+      </dd>
     </dl>
 
     <h3><a name="elementsTime">Time keeping</a></h3>

docs/schemas/domaincommon.rng

@@ -4569,6 +4569,9 @@
               </optional>
             </element>
           </optional>
+          <optional>
+            <ref name="ioapic"/>
+          </optional>
         </interleave>
       </element>
     </optional>
@@ -4747,6 +4750,18 @@
     </element>
   </define>
 
+  <define name="ioapic">
+    <element name="ioapic">
+      <attribute name="driver">
+        <choice>
+          <value>qemu</value>
+          <value>kvm</value>
+        </choice>
+      </attribute>
+      <empty/>
+    </element>
+  </define>
+
   <define name="address">
     <element name="address">
       <choice>

src/conf/domain_conf.c

@@ -141,7 +141,8 @@ VIR_ENUM_IMPL(virDomainFeature, VIR_DOMAIN_FEATURE_LAST,
               "pmu",
               "vmport",
               "gic",
-              "smm")
+              "smm",
+              "ioapic")
 
 VIR_ENUM_IMPL(virDomainCapabilitiesPolicy, VIR_DOMAIN_CAPABILITIES_POLICY_LAST,
               "default",
@@ -859,6 +860,11 @@ VIR_ENUM_IMPL(virDomainLoader,
               "rom",
               "pflash")
 
+VIR_ENUM_IMPL(virDomainIOAPIC,
+              VIR_DOMAIN_IOAPIC_LAST,
+              "qemu",
+              "kvm")
+
 /* Internal mapping: subset of block job types that can be present in
  * <mirror> XML (remaining types are not two-phase). */
 VIR_ENUM_DECL(virDomainBlockJob)
@@ -17527,6 +17533,24 @@ virDomainDefParseXML(xmlDocPtr xml,
             ctxt->node = node;
             break;
 
+        case VIR_DOMAIN_FEATURE_IOAPIC:
+            node = ctxt->node;
+            ctxt->node = nodes[i];
+            tmp = virXPathString("string(./@driver)", ctxt);
+            if (tmp) {
+                int value = virDomainIOAPICTypeFromString(tmp);
+                if (value < 0) {
+                    virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                                   _("Unknown driver mode: %s"),
+                                   tmp);
+                    goto error;
+                }
+                def->ioapic = value;
+                def->features[val] = VIR_TRISTATE_SWITCH_ON;
+            }
+            ctxt->node = node;
+            break;
+
         /* coverity[dead_error_begin] */
         case VIR_DOMAIN_FEATURE_LAST:
             break;
@@ -24627,6 +24651,13 @@ virDomainDefFormatInternal(virDomainDefPtr def,
                 }
                 break;
 
+            case VIR_DOMAIN_FEATURE_IOAPIC:
+                if (def->features[i] == VIR_TRISTATE_SWITCH_ON) {
+                    virBufferAsprintf(buf, "<ioapic driver='%s'/>\n",
+                                      virDomainIOAPICTypeToString(def->ioapic));
+                }
+                break;
+
             /* coverity[dead_error_begin] */
             case VIR_DOMAIN_FEATURE_LAST:
                 break;

src/conf/domain_conf.h

@@ -1670,6 +1670,7 @@ typedef enum {
     VIR_DOMAIN_FEATURE_VMPORT,
     VIR_DOMAIN_FEATURE_GIC,
     VIR_DOMAIN_FEATURE_SMM,
+    VIR_DOMAIN_FEATURE_IOAPIC,
 
     VIR_DOMAIN_FEATURE_LAST
 } virDomainFeature;
@@ -1809,6 +1810,15 @@ struct _virDomainLoaderDef {
 
 void virDomainLoaderDefFree(virDomainLoaderDefPtr loader);
 
+typedef enum {
+    VIR_DOMAIN_IOAPIC_QEMU = 0,
+    VIR_DOMAIN_IOAPIC_KVM,
+
+    VIR_DOMAIN_IOAPIC_LAST
+} virDomainIOAPIC;
+
+VIR_ENUM_DECL(virDomainIOAPIC);
+
 /* Operating system configuration data & machine / arch */
 typedef struct _virDomainOSDef virDomainOSDef;
 typedef virDomainOSDef *virDomainOSDefPtr;
@@ -2258,6 +2268,7 @@ struct _virDomainDef {
     unsigned int hyperv_spinlocks;
     virGICVersion gic_version;
     char *hyperv_vendor_id;
+    virDomainIOAPIC ioapic;
 
     /* These options are of type virTristateSwitch: ON = keep, OFF = drop */
     int caps_features[VIR_DOMAIN_CAPS_FEATURE_LAST];

tests/qemuxml2argvdata/qemuxml2argv-intel-iommu-ioapic.xml

@@ -0,0 +1,29 @@
+<domain type='kvm'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219100</memory>
+  <currentMemory unit='KiB'>219100</currentMemory>
+  <vcpu placement='static'>1</vcpu>
+  <os>
+    <type arch='x86_64' machine='q35'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <features>
+    <ioapic driver='qemu'/>
+  </features>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu-system-x86_64</emulator>
+    <controller type='pci' index='0' model='pcie-root'/>
+    <controller type='sata' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/>
+    </controller>
+    <input type='mouse' bus='ps2'/>
+    <input type='keyboard' bus='ps2'/>
+    <memballoon model='none'/>
+    <iommu model='intel'/>
+  </devices>
+</domain>

tests/qemuxml2xmloutdata/qemuxml2xmlout-intel-iommu-ioapic.xml

@@ -0,0 +1 @@
+../qemuxml2argvdata/qemuxml2argv-intel-iommu-ioapic.xml

tests/qemuxml2xmltest.c

@@ -1122,6 +1122,7 @@ mymain(void)
     DO_TEST("intel-iommu-machine",
             QEMU_CAPS_MACHINE_OPT,
             QEMU_CAPS_MACHINE_IOMMU);
+    DO_TEST("intel-iommu-ioapic", NONE);
 
     DO_TEST("cpu-check-none", NONE);
     DO_TEST("cpu-check-partial", NONE);