Add virtio-related options to interfaces

<interface type='user'>
  <mac address='52:54:56:5a:5c:5e'/>
  <model type='virtio'/>
  <driver iommu='on' ats='on'/>
</interface>

https://bugzilla.redhat.com/show_bug.cgi?id=1283251

Reviewed-by: Pavel Hrdina <phrdina@redhat.com>

docs/formatdomain.html.in

@@ -3451,6 +3451,19 @@
       </dd>
     </dl>
 
+    <h4><a name="elementsVirtio">Virtio-related options</a></h4>
+
+    <p>
+      QEMU's virtio devices have some attributes related to the virtio transport under
+      the <code>driver</code> element:
+      The <code>iommu</code> attribute enables the use of emulated IOMMU
+      by the device. The attribute <code>ats</code> controls the Address
+      Translation Service support for PCIe devices. This is needed to make use
+      of IOTLB support (see <a href="#elementsIommu">IOMMU device</a>).
+      Possible values are <code>on</code> or <code>off</code>.
+      <span class="since">Since 3.5.0</span>
+    </p>
+
     <h4><a name="elementsControllers">Controllers</a></h4>
 
     <p>
@@ -5142,6 +5155,12 @@ qemu-kvm -net nic,model=? /dev/null
         <b>In general you should leave this option alone, unless you
         are very certain you know what you are doing.</b>
       </dd>
+      <dt>virtio options</dt>
+      <dd>
+        For virtio interfaces,
+        <a href="#elementsVirtio">Virtio-specific options</a> can also be
+        set. (<span class="since">Since 3.5.0</span>)
+      </dd>
     </dl>
     <p>
       Offloading options for the host and guest can be configured using

docs/schemas/domaincommon.rng

@@ -2686,6 +2686,7 @@
               </optional>
             </group>
           </choice>
+          <ref name="virtioOptions"/>
           <interleave>
             <optional>
               <element name='host'>
@@ -5006,6 +5007,17 @@
     </element>
   </define>
 
+  <define name="virtioOptions">
+    <optional>
+      <attribute name="iommu">
+        <ref name="virOnOff"/>
+      </attribute>
+      <attribute name="ats">
+        <ref name="virOnOff"/>
+      </attribute>
+    </optional>
+  </define>
+
   <define name="usbmaster">
     <element name="master">
       <attribute name="startport">

src/conf/domain_conf.c

@@ -1112,6 +1112,46 @@ virDomainXMLOptionGetNamespace(virDomainXMLOptionPtr xmlopt)
     return &xmlopt->ns;
 }
 
+static int
+virDomainVirtioOptionsParseXML(xmlXPathContextPtr ctxt,
+                               virDomainVirtioOptionsPtr *virtio)
+{
+    char *str = NULL;
+    int ret = -1;
+    int val;
+    virDomainVirtioOptionsPtr res;
+
+    if (VIR_ALLOC(*virtio) < 0)
+        return -1;
+
+    res = *virtio;
+
+    if ((str = virXPathString("string(./driver/@iommu)", ctxt))) {
+        if ((val = virTristateSwitchTypeFromString(str)) <= 0) {
+            virReportError(VIR_ERR_XML_ERROR, "%s",
+                           _("invalid iommu value"));
+            goto cleanup;
+        }
+        res->iommu = val;
+    }
+    VIR_FREE(str);
+
+    if ((str = virXPathString("string(./driver/@ats)", ctxt))) {
+        if ((val = virTristateSwitchTypeFromString(str)) <= 0) {
+            virReportError(VIR_ERR_XML_ERROR, "%s",
+                           _("invalid ats value"));
+            goto cleanup;
+        }
+        res->ats = val;
+    }
+
+    ret = 0;
+
+ cleanup:
+    VIR_FREE(str);
+    return ret;
+}
+
 
 virSaveCookieCallbacksPtr
 virDomainXMLOptionGetSaveCookie(virDomainXMLOptionPtr xmlopt)
@@ -1966,6 +2006,7 @@ virDomainNetDefClear(virDomainNetDefPtr def)
     VIR_FREE(def->ifname);
     VIR_FREE(def->ifname_guest);
     VIR_FREE(def->ifname_guest_actual);
+    VIR_FREE(def->virtio);
 
     virNetDevIPInfoClear(&def->guestIP);
     virNetDevIPInfoClear(&def->hostIP);
@@ -4339,6 +4380,28 @@ virDomainHostdevDefPostParse(virDomainHostdevDefPtr dev,
 }
 
 
+static int
+virDomainCheckVirtioOptions(virDomainVirtioOptionsPtr virtio)
+{
+    if (!virtio)
+        return 0;
+
+    if (virtio->iommu != VIR_TRISTATE_SWITCH_ABSENT) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("iommu driver option is only supported "
+                         "for virtio devices"));
+        return -1;
+    }
+    if (virtio->ats != VIR_TRISTATE_SWITCH_ABSENT) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("ats driver option is only supported "
+                         "for virtio devices"));
+        return -1;
+    }
+    return 0;
+}
+
+
 static int
 virDomainDeviceDefPostParseInternal(virDomainDeviceDefPtr dev,
                                     const virDomainDef *def,
@@ -4437,6 +4500,13 @@ virDomainDeviceDefPostParseInternal(virDomainDeviceDefPtr dev,
         }
     }
 
+    if (dev->type == VIR_DOMAIN_DEVICE_NET) {
+        virDomainNetDefPtr net = dev->data.net;
+        if (STRNEQ_NULLABLE(net->model, "virtio") &&
+            virDomainCheckVirtioOptions(net->virtio) < 0)
+            return -1;
+    }
+
     return 0;
 }
 
@@ -5235,6 +5305,24 @@ virDomainDefValidate(virDomainDefPtr def,
 }
 
 
+static void
+virDomainVirtioOptionsFormat(virBufferPtr buf,
+                             virDomainVirtioOptionsPtr virtio)
+{
+    if (!virtio)
+        return;
+
+    if (virtio->iommu != VIR_TRISTATE_SWITCH_ABSENT) {
+        virBufferAsprintf(buf, " iommu='%s'",
+                          virTristateSwitchTypeToString(virtio->iommu));
+    }
+    if (virtio->ats != VIR_TRISTATE_SWITCH_ABSENT) {
+        virBufferAsprintf(buf, " ats='%s'",
+                          virTristateSwitchTypeToString(virtio->ats));
+    }
+}
+
+
 /* Generate a string representation of a device address
  * @info address Device address to stringify
  */
@@ -10381,6 +10469,9 @@ virDomainNetDefParseXML(virDomainXMLOptionPtr xmlopt,
             goto error;
     }
 
+    if (virDomainVirtioOptionsParseXML(ctxt, &def->virtio) < 0)
+        goto error;
+
  cleanup:
     ctxt->node = oldnode;
     VIR_FREE(macaddr);
@@ -19004,6 +19095,30 @@ virDomainDeviceInfoCheckABIStability(virDomainDeviceInfoPtr src,
 }
 
 
+static bool
+virDomainVirtioOptionsCheckABIStability(virDomainVirtioOptionsPtr src,
+                                        virDomainVirtioOptionsPtr dst)
+{
+    if (src->iommu != dst->iommu) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("Target device iommu option '%s' does not "
+                         "match source '%s'"),
+                       virTristateSwitchTypeToString(dst->iommu),
+                       virTristateSwitchTypeToString(src->iommu));
+        return false;
+    }
+    if (src->ats != dst->ats) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("Target device ats option '%s' does not "
+                         "match source '%s'"),
+                       virTristateSwitchTypeToString(dst->ats),
+                       virTristateSwitchTypeToString(src->ats));
+        return false;
+    }
+    return true;
+}
+
+
 static bool
 virDomainDiskDefCheckABIStability(virDomainDiskDefPtr src,
                                   virDomainDiskDefPtr dst)
@@ -19163,6 +19278,10 @@ virDomainNetDefCheckABIStability(virDomainNetDefPtr src,
         return false;
     }
 
+    if (src->virtio && dst->virtio &&
+        !virDomainVirtioOptionsCheckABIStability(src->virtio, dst->virtio))
+        return false;
+
     if (!virDomainDeviceInfoCheckABIStability(&src->info, &dst->info))
         return false;
 
@@ -22118,6 +22237,8 @@ virDomainVirtioNetDriverFormat(char **outstr,
         virBufferAsprintf(&buf, " rx_queue_size='%u'",
                           def->driver.virtio.rx_queue_size);
 
+    virDomainVirtioOptionsFormat(&buf, def->virtio);
+
     if (virBufferCheckError(&buf) < 0)
         return -1;
 

src/conf/domain_conf.h

@@ -156,6 +156,9 @@ typedef virDomainTPMDef *virDomainTPMDefPtr;
 typedef struct _virDomainIOMMUDef virDomainIOMMUDef;
 typedef virDomainIOMMUDef *virDomainIOMMUDefPtr;
 
+typedef struct _virDomainVirtioOptions virDomainVirtioOptions;
+typedef virDomainVirtioOptions *virDomainVirtioOptionsPtr;
+
 /* Flags for the 'type' field in virDomainDeviceDef */
 typedef enum {
     VIR_DOMAIN_DEVICE_NONE = 0,
@@ -1040,6 +1043,7 @@ struct _virDomainNetDef {
     int linkstate;
     unsigned int mtu;
     virNetDevCoalescePtr coalesce;
+    virDomainVirtioOptionsPtr virtio;
 };
 
 typedef enum {
@@ -2215,6 +2219,12 @@ struct _virDomainIOMMUDef {
     virTristateSwitch eim;
     virTristateSwitch iotlb;
 };
+
+struct _virDomainVirtioOptions {
+    virTristateSwitch iommu;
+    virTristateSwitch ats;
+};
+
 /*
  * Guest VM main configuration
  *

tests/qemuxml2argvdata/qemuxml2argv-virtio-options.xml

@@ -47,6 +47,7 @@
     <interface type='user'>
       <mac address='52:54:56:58:5a:5c'/>
       <model type='virtio'/>
+      <driver iommu='on' ats='on'/>
       <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
     </interface>
     <input type='mouse' bus='virtio'>