qemu: wire up virtio-net segment offloading options

Format the segment offloading options specified by
<driver>
  <host .../>
  <guest .../>
</driver>
on virtio-net command line.

src/qemu/qemu_command.c

@@ -4473,6 +4473,50 @@ qemuBuildNicDevStr(virDomainDefPtr def,
             virBufferAsprintf(&buf, ",event_idx=%s",
                               virTristateSwitchTypeToString(net->driver.virtio.event_idx));
         }
+        if (net->driver.virtio.host.csum) {
+            virBufferAsprintf(&buf, ",csum=%s",
+                              virTristateSwitchTypeToString(net->driver.virtio.host.csum));
+        }
+        if (net->driver.virtio.host.gso) {
+            virBufferAsprintf(&buf, ",gso=%s",
+                              virTristateSwitchTypeToString(net->driver.virtio.host.gso));
+        }
+        if (net->driver.virtio.host.tso4) {
+            virBufferAsprintf(&buf, ",host_tso4=%s",
+                              virTristateSwitchTypeToString(net->driver.virtio.host.tso4));
+        }
+        if (net->driver.virtio.host.tso6) {
+            virBufferAsprintf(&buf, ",host_tso6=%s",
+                              virTristateSwitchTypeToString(net->driver.virtio.host.tso6));
+        }
+        if (net->driver.virtio.host.ecn) {
+            virBufferAsprintf(&buf, ",host_ecn=%s",
+                              virTristateSwitchTypeToString(net->driver.virtio.host.ecn));
+        }
+        if (net->driver.virtio.host.ufo) {
+            virBufferAsprintf(&buf, ",host_ufo=%s",
+                              virTristateSwitchTypeToString(net->driver.virtio.host.ufo));
+        }
+        if (net->driver.virtio.guest.csum) {
+            virBufferAsprintf(&buf, ",guest_csum=%s",
+                              virTristateSwitchTypeToString(net->driver.virtio.guest.csum));
+        }
+        if (net->driver.virtio.guest.tso4) {
+            virBufferAsprintf(&buf, ",guest_tso4=%s",
+                              virTristateSwitchTypeToString(net->driver.virtio.guest.tso4));
+        }
+        if (net->driver.virtio.guest.tso6) {
+            virBufferAsprintf(&buf, ",guest_tso6=%s",
+                              virTristateSwitchTypeToString(net->driver.virtio.guest.tso6));
+        }
+        if (net->driver.virtio.guest.ecn) {
+            virBufferAsprintf(&buf, ",guest_ecn=%s",
+                              virTristateSwitchTypeToString(net->driver.virtio.guest.ecn));
+        }
+        if (net->driver.virtio.guest.ufo) {
+            virBufferAsprintf(&buf, ",guest_ufo=%s",
+                              virTristateSwitchTypeToString(net->driver.virtio.guest.ufo));
+        }
     }
     if (usingVirtio && vhostfdSize > 1) {
         /* As advised at http://www.linux-kvm.org/page/Multiqueue

tests/qemuxml2argvdata/qemuxml2argv-net-virtio-disable-offloads.args

+LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test QEMU_AUDIO_DRV=none \
+/usr/bin/qemu -S -M pc -m 214 -smp 1 -nographic -nodefconfig -nodefaults \
+-monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot c -usb \
+-hda /dev/HostVG/QEMUGuest7 \
+-device virtio-net-pci,csum=off,gso=off,\
+host_tso4=off,host_tso6=off,host_ecn=off,host_ufo=off,\
+guest_csum=off,guest_tso4=off,guest_tso6=off,guest_ecn=off,guest_ufo=off,\
+vlan=0,id=net0,mac=00:22:44:66:88:aa,bus=pci.0,addr=0x3 \
+-net user,vlan=0,name=hostnet0 \
+-device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x4

tests/qemuxml2argvtest.c

@@ -970,6 +970,8 @@ mymain(void)
     DO_TEST("net-virtio", NONE);
     DO_TEST("net-virtio-device",
             QEMU_CAPS_DEVICE, QEMU_CAPS_NODEFCONFIG, QEMU_CAPS_VIRTIO_TX_ALG);
+    DO_TEST("net-virtio-disable-offloads",
+            QEMU_CAPS_DEVICE, QEMU_CAPS_NODEFCONFIG);
     DO_TEST("net-virtio-netdev",
             QEMU_CAPS_DEVICE, QEMU_CAPS_NETDEV, QEMU_CAPS_NODEFCONFIG);
     DO_TEST("net-virtio-s390",