Add support for virtio-net.tx_queue_size

https://bugzilla.redhat.com/show_bug.cgi?id=1462653

Just like I've added support for setting rx_queue_size (in
c56cdf259 and friends), qemu just gained support for setting tx
ring size.

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

docs/formatdomain.html.in

@@ -5074,7 +5074,7 @@ qemu-kvm -net nic,model=? /dev/null
     <source network='default'/>
     <target dev='vnet1'/>
     <model type='virtio'/>
-    <b>&lt;driver name='vhost' txmode='iothread' ioeventfd='on' event_idx='off' queues='5' rx_queue_size='256'&gt;
+    <b>&lt;driver name='vhost' txmode='iothread' ioeventfd='on' event_idx='off' queues='5' rx_queue_size='256' tx_queue_size='256'&gt;
       &lt;host csum='off' gso='off' tso4='off' tso6='off' ecn='off' ufo='off' mrg_rxbuf='off'/&gt;
       &lt;guest csum='off' tso4='off' tso6='off' ecn='off' ufo='off'/&gt;
     &lt;/driver&gt;
@@ -5204,6 +5204,19 @@ 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><code>tx_queue_size</code></dt>
+      <dd>
+        The optional <code>tx_queue_size</code> attribute controls
+        the size of virtio ring for each queue as described above.
+        The default value is hypervisor dependent and may change
+        across its releases. Moreover, some hypervisors may pose
+        some restrictions on actual value. For instance, QEMU
+        v2.9  requires value to be a power of two from [256, 1024] range.
+        <span class="since">Since 3.7.0 (QEMU and KVM only)</span><br/><br/>
+
+        <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,

docs/schemas/domaincommon.rng

@@ -2711,6 +2711,11 @@
                   <ref name='positiveInteger'/>
                 </attribute>
               </optional>
+              <optional>
+                <attribute name='tx_queue_size'>
+                  <ref name='positiveInteger'/>
+                </attribute>
+              </optional>
               <optional>
                 <attribute name="txmode">
                   <choice>

src/conf/domain_conf.c

@@ -9833,6 +9833,7 @@ virDomainNetDefParseXML(virDomainXMLOptionPtr xmlopt,
     char *event_idx = NULL;
     char *queues = NULL;
     char *rx_queue_size = NULL;
+    char *tx_queue_size = NULL;
     char *str = NULL;
     char *filter = NULL;
     char *internal = NULL;
@@ -10006,6 +10007,7 @@ virDomainNetDefParseXML(virDomainXMLOptionPtr xmlopt,
                 event_idx = virXMLPropString(cur, "event_idx");
                 queues = virXMLPropString(cur, "queues");
                 rx_queue_size = virXMLPropString(cur, "rx_queue_size");
+                tx_queue_size = virXMLPropString(cur, "tx_queue_size");
             } else if (xmlStrEqual(cur->name, BAD_CAST "filterref")) {
                 if (filter) {
                     virReportError(VIR_ERR_XML_ERROR, "%s",
@@ -10403,6 +10405,16 @@ virDomainNetDefParseXML(virDomainXMLOptionPtr xmlopt,
             }
             def->driver.virtio.rx_queue_size = q;
         }
+        if (tx_queue_size) {
+            unsigned int q;
+            if (virStrToLong_uip(tx_queue_size, NULL, 10, &q) < 0) {
+                virReportError(VIR_ERR_XML_DETAIL,
+                               _("'tx_queue_size' attribute must be positive number: %s"),
+                               tx_queue_size);
+                goto error;
+            }
+            def->driver.virtio.tx_queue_size = q;
+        }
         if ((str = virXPathString("string(./driver/host/@csum)", ctxt))) {
             if ((val = virTristateSwitchTypeFromString(str)) <= 0) {
                 virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
@@ -10600,6 +10612,7 @@ virDomainNetDefParseXML(virDomainXMLOptionPtr xmlopt,
     VIR_FREE(event_idx);
     VIR_FREE(queues);
     VIR_FREE(rx_queue_size);
+    VIR_FREE(tx_queue_size);
     VIR_FREE(str);
     VIR_FREE(filter);
     VIR_FREE(type);
@@ -22497,6 +22510,9 @@ virDomainVirtioNetDriverFormat(char **outstr,
     if (def->driver.virtio.rx_queue_size)
         virBufferAsprintf(&buf, " rx_queue_size='%u'",
                           def->driver.virtio.rx_queue_size);
+    if (def->driver.virtio.tx_queue_size)
+        virBufferAsprintf(&buf, " tx_queue_size='%u'",
+                          def->driver.virtio.tx_queue_size);
 
     virDomainVirtioOptionsFormat(&buf, def->virtio);
 

src/conf/domain_conf.h

@@ -969,6 +969,7 @@ struct _virDomainNetDef {
             virTristateSwitch event_idx;
             unsigned int queues; /* Multiqueue virtio-net */
             unsigned int rx_queue_size;
+            unsigned int tx_queue_size;
             struct {
                 virTristateSwitch csum;
                 virTristateSwitch gso;

src/qemu/qemu_capabilities.c

@@ -435,7 +435,8 @@ VIR_ENUM_IMPL(virQEMUCaps, QEMU_CAPS_LAST,
 
               /* 265 */
               "spapr-pci-host-bridge.numa_node",
-              "vnc-multi-servers"
+              "vnc-multi-servers",
+              "virtio-net.tx_queue_size",
     );
 
 
@@ -1705,6 +1706,7 @@ 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 },
+    { "tx_queue_size", QEMU_CAPS_VIRTIO_NET_TX_QUEUE_SIZE },
     { "host_mtu", QEMU_CAPS_VIRTIO_NET_HOST_MTU },
 };
 

src/qemu/qemu_capabilities.h

@@ -422,6 +422,7 @@ typedef enum {
     /* 265 */
     QEMU_CAPS_SPAPR_PCI_HOST_BRIDGE_NUMA_NODE, /* spapr-pci-host-bridge.numa_node= */
     QEMU_CAPS_VNC_MULTI_SERVERS, /* -vnc vnc=unix:/path */
+    QEMU_CAPS_VIRTIO_NET_TX_QUEUE_SIZE, /* virtio-net-*.tx_queue_size */
 
     QEMU_CAPS_LAST /* this must always be the last item */
 } virQEMUCapsFlags;

src/qemu/qemu_command.c

@@ -3725,6 +3725,14 @@ qemuBuildNicDevStr(virDomainDefPtr def,
         }
         virBufferAsprintf(&buf, ",rx_queue_size=%u", net->driver.virtio.rx_queue_size);
     }
+    if (usingVirtio && net->driver.virtio.tx_queue_size) {
+        if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_VIRTIO_NET_TX_QUEUE_SIZE)) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("virtio tx_queue_size option is not supported with this QEMU binary"));
+            goto error;
+        }
+        virBufferAsprintf(&buf, ",tx_queue_size=%u", net->driver.virtio.tx_queue_size);
+    }
 
     if (usingVirtio && net->mtu) {
         if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_VIRTIO_NET_HOST_MTU)) {

src/qemu/qemu_domain.c

@@ -3226,12 +3226,18 @@ qemuDomainDeviceDefValidate(const virDomainDeviceDef *dev,
             goto cleanup;
         }
 
-        if (STREQ_NULLABLE(net->model, "virtio") &&
+        if (STREQ_NULLABLE(net->model, "virtio")) {
-            net->driver.virtio.rx_queue_size & (net->driver.virtio.rx_queue_size - 1)) {
+            if (net->driver.virtio.rx_queue_size & (net->driver.virtio.rx_queue_size - 1)) {
                 virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
                                _("rx_queue_size has to be a power of two"));
                 goto cleanup;
             }
+            if (net->driver.virtio.tx_queue_size & (net->driver.virtio.tx_queue_size - 1)) {
+                virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                               _("tx_queue_size has to be a power of two"));
+                goto cleanup;
+            }
+        }
 
         if (net->mtu &&
             !qemuDomainNetSupportsMTU(net->type)) {

tests/qemuxml2argvdata/qemuxml2argv-net-virtio-rxtxqueuesize.args

@@ -21,7 +21,7 @@ server,nowait \
 -usb \
 -drive file=/dev/HostVG/QEMUGuest1,format=raw,if=none,id=drive-ide0-0-0 \
 -device ide-drive,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0 \
--device virtio-net-pci,rx_queue_size=512,vlan=0,id=net0,mac=00:11:22:33:44:55,\
+-device virtio-net-pci,rx_queue_size=512,tx_queue_size=1024,vlan=0,id=net0,\
-bus=pci.0,addr=0x3 \
+mac=00:11:22:33:44:55,bus=pci.0,addr=0x3 \
 -net user,vlan=0,name=hostnet0 \
 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x4

tests/qemuxml2argvdata/qemuxml2argv-net-virtio-rxtxqueuesize.xml

@@ -22,7 +22,7 @@
     <interface type='user'>
       <mac address='00:11:22:33:44:55'/>
       <model type='virtio'/>
-      <driver rx_queue_size='512'/>
+      <driver rx_queue_size='512' tx_queue_size='1024'/>
     </interface>
     <memballoon model='virtio'/>
   </devices>

tests/qemuxml2argvtest.c

@@ -1167,8 +1167,9 @@ mymain(void)
             QEMU_CAPS_VIRTIO_S390);
     DO_TEST("net-virtio-ccw",
             QEMU_CAPS_VIRTIO_CCW, QEMU_CAPS_VIRTIO_S390);
-    DO_TEST("net-virtio-rxqueuesize",
+    DO_TEST("net-virtio-rxtxqueuesize",
-            QEMU_CAPS_VIRTIO_NET_RX_QUEUE_SIZE);
+            QEMU_CAPS_VIRTIO_NET_RX_QUEUE_SIZE,
+            QEMU_CAPS_VIRTIO_NET_TX_QUEUE_SIZE);
     DO_TEST_PARSE_ERROR("net-virtio-rxqueuesize-invalid-size", NONE);
     DO_TEST("net-eth", NONE);
     DO_TEST("net-eth-ifname", NONE);

tests/qemuxml2xmloutdata/qemuxml2xmlout-net-virtio-rxtxqueuesize.xml

@@ -29,7 +29,7 @@
     <interface type='user'>
       <mac address='00:11:22:33:44:55'/>
       <model type='virtio'/>
-      <driver rx_queue_size='512'/>
+      <driver rx_queue_size='512' tx_queue_size='1024'/>
       <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
     </interface>
     <input type='mouse' bus='ps2'/>

tests/qemuxml2xmltest.c

@@ -537,7 +537,7 @@ mymain(void)
     DO_TEST("net-eth-ifname", NONE);
     DO_TEST("net-eth-hostip", NONE);
     DO_TEST("net-virtio-network-portgroup", NONE);
-    DO_TEST("net-virtio-rxqueuesize", NONE);
+    DO_TEST("net-virtio-rxtxqueuesize", NONE);
     DO_TEST("net-hostdev", NONE);
     DO_TEST("net-hostdev-vfio", NONE);
     DO_TEST("net-midonet", NONE);