qemu: Implement mtu on interface

Not only we should set the MTU on the host end of the device but
also let qemu know what MTU did we set.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

src/qemu/qemu_capabilities.c

@@ -356,6 +356,7 @@ VIR_ENUM_IMPL(virQEMUCaps, QEMU_CAPS_LAST,
               "drive-iotune-group",
 
               "query-cpu-model-expansion", /* 245 */
+              "virtio-net.host_mtu",
     );
 
 
@@ -1642,6 +1643,7 @@ static struct virQEMUCapsStringFlags virQEMUCapsObjectPropsVirtioNet[] = {
     { "tx", QEMU_CAPS_VIRTIO_TX_ALG },
     { "event_idx", QEMU_CAPS_VIRTIO_NET_EVENT_IDX },
     { "rx_queue_size", QEMU_CAPS_VIRTIO_NET_RX_QUEUE_SIZE },
+    { "host_mtu", QEMU_CAPS_VIRTIO_NET_HOST_MTU },
 };
 
 static struct virQEMUCapsStringFlags virQEMUCapsObjectPropsVirtioSCSI[] = {

src/qemu/qemu_capabilities.h

@@ -392,6 +392,7 @@ typedef enum {
 
     /* 245 */
     QEMU_CAPS_QUERY_CPU_MODEL_EXPANSION, /* qmp query-cpu-model-expansion */
+    QEMU_CAPS_VIRTIO_NET_HOST_MTU, /* virtio-net-*.host_mtu */
 
     QEMU_CAPS_LAST /* this must always be the last item */
 } virQEMUCapsFlags;

src/qemu/qemu_command.c

@@ -3678,6 +3678,16 @@ qemuBuildNicDevStr(virDomainDefPtr def,
         }
         virBufferAsprintf(&buf, ",rx_queue_size=%u", net->driver.virtio.rx_queue_size);
     }
+
+    if (usingVirtio && net->mtu) {
+        if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_VIRTIO_NET_HOST_MTU)) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("setting MTU is not supported with this QEMU binary"));
+            goto error;
+        }
+        virBufferAsprintf(&buf, ",host_mtu=%u", net->mtu);
+    }
+
     if (vlan == -1)
         virBufferAsprintf(&buf, ",netdev=host%s", net->info.alias);
     else
@@ -8251,6 +8261,10 @@ qemuBuildInterfaceCommandLine(virQEMUDriverPtr driver,
         }
     }
 
+    if (net->mtu &&
+        virNetDevSetMTU(net->ifname, net->mtu) < 0)
+        goto cleanup;
+
     if ((actualType == VIR_DOMAIN_NET_TYPE_NETWORK ||
          actualType == VIR_DOMAIN_NET_TYPE_BRIDGE ||
          actualType == VIR_DOMAIN_NET_TYPE_ETHERNET ||

src/qemu/qemu_domain.c

@@ -6541,14 +6541,15 @@ bool
 qemuDomainNetSupportsMTU(virDomainNetType type)
 {
     switch (type) {
-    case VIR_DOMAIN_NET_TYPE_USER:
+    case VIR_DOMAIN_NET_TYPE_NETWORK:
+    case VIR_DOMAIN_NET_TYPE_BRIDGE:
     case VIR_DOMAIN_NET_TYPE_ETHERNET:
     case VIR_DOMAIN_NET_TYPE_VHOSTUSER:
+        return true;
+    case VIR_DOMAIN_NET_TYPE_USER:
     case VIR_DOMAIN_NET_TYPE_SERVER:
     case VIR_DOMAIN_NET_TYPE_CLIENT:
     case VIR_DOMAIN_NET_TYPE_MCAST:
-    case VIR_DOMAIN_NET_TYPE_NETWORK:
-    case VIR_DOMAIN_NET_TYPE_BRIDGE:
     case VIR_DOMAIN_NET_TYPE_INTERNAL:
     case VIR_DOMAIN_NET_TYPE_DIRECT:
     case VIR_DOMAIN_NET_TYPE_HOSTDEV:

tests/qemuxml2xmloutdata/qemuxml2xmlout-net-mtu.xml

+<domain type='qemu'>
+  <name>test</name>
+  <uuid>15d091de-0181-456b-9554-e4382dc1f1ab</uuid>
+  <memory unit='KiB'>1048576</memory>
+  <currentMemory unit='KiB'>1048576</currentMemory>
+  <vcpu placement='static'>1</vcpu>
+  <os>
+    <type arch='x86_64' machine='pc-0.13'>hvm</type>
+    <boot dev='cdrom'/>
+    <boot dev='hd'/>
+    <bootmenu enable='yes'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>restart</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu</emulator>
+    <disk type='file' device='disk'>
+      <driver name='qemu' type='qcow2' event_idx='on'/>
+      <source file='/var/lib/libvirt/images/f14.img'/>
+      <target dev='vda' bus='virtio'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
+    </disk>
+    <disk type='file' device='cdrom'>
+      <driver name='qemu' type='raw'/>
+      <source file='/var/lib/libvirt/Fedora-14-x86_64-Live-KDE.iso'/>
+      <target dev='hdc' bus='ide'/>
+      <readonly/>
+      <address type='drive' controller='0' bus='1' target='0' unit='0'/>
+    </disk>
+    <controller type='usb' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
+    </controller>
+    <controller type='virtio-serial' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
+    </controller>
+    <controller type='ide' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
+    </controller>
+    <controller type='pci' index='0' model='pci-root'/>
+    <interface type='network'>
+      <mac address='52:54:00:e5:48:58'/>
+      <source network='default'/>
+      <model type='virtio'/>
+      <mtu size='1500'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
+    </interface>
+    <interface type='network'>
+      <mac address='52:54:00:e5:48:59'/>
+      <source network='default'/>
+      <model type='virtio'/>
+      <mtu size='9000'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
+    </interface>
+    <serial type='pty'>
+      <target port='0'/>
+    </serial>
+    <console type='pty'>
+      <target type='serial' port='0'/>
+    </console>
+    <input type='mouse' bus='ps2'/>
+    <input type='keyboard' bus='ps2'/>
+    <memballoon model='virtio'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
+    </memballoon>
+  </devices>
+</domain>

tests/qemuxml2xmltest.c

@@ -524,6 +524,7 @@ mymain(void)
     DO_TEST("watchdog", NONE);
     DO_TEST("net-bandwidth", NONE);
     DO_TEST("net-bandwidth2", NONE);
+    DO_TEST("net-mtu", NONE);
 
     DO_TEST("serial-vc", NONE);
     DO_TEST("serial-pty", NONE);