qemu: Allow use of iothreads for disk definitions

For virtio-blk-pci disks with the disk iothread attribute that are
running the correct emulator, add the "iothread=iothread#" to the
-device command line in order to enable iothreads for the disk as
long as the command is available, the disk iothread value provided is
valid, and is supported for the disk device being added

src/qemu/qemu_command.c

@@ -3674,6 +3674,39 @@ qemuBuildDriveStr(virConnectPtr conn,
     return NULL;
 }
 
+
+static bool
+qemuCheckIothreads(virDomainDefPtr def,
+                   virQEMUCapsPtr qemuCaps,
+                   virDomainDiskDefPtr disk)
+{
+    /* Have capability */
+    if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_OBJECT_IOTHREAD)) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("IOThreads not supported for this QEMU"));
+        return false;
+    }
+
+    /* Right "type" of disk" */
+    if (disk->bus != VIR_DOMAIN_DISK_BUS_VIRTIO &&
+        disk->info.type != VIR_DOMAIN_DEVICE_ADDRESS_TYPE_PCI) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("IOThreads only available for virtio pci disk"));
+        return false;
+    }
+
+    /* Value larger than iothreads available? */
+    if (disk->iothread > def->iothreads) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("Disk iothread '%u' invalid only %u IOThreads"),
+                       disk->iothread, def->iothreads);
+        return false;
+    }
+
+    return true;
+}
+
+
 char *
 qemuBuildDriveDevStr(virDomainDefPtr def,
                      virDomainDiskDefPtr disk,
@@ -3698,6 +3731,9 @@ qemuBuildDriveDevStr(virDomainDefPtr def,
         }
     }
 
+    if (disk->iothread && !qemuCheckIothreads(def, qemuCaps, disk))
+        goto error;
+
     switch (disk->bus) {
     case VIR_DOMAIN_DISK_BUS_IDE:
         if (disk->info.addr.drive.target != 0) {
@@ -3875,6 +3911,8 @@ qemuBuildDriveDevStr(virDomainDefPtr def,
             virBufferAddLit(&opt, "virtio-blk-device");
         } else {
             virBufferAddLit(&opt, "virtio-blk-pci");
+            if (disk->iothread)
+                virBufferAsprintf(&opt, ",iothread=iothread%u", disk->iothread);
         }
         qemuBuildIoEventFdStr(&opt, disk->ioeventfd, qemuCaps);
         if (disk->event_idx &&

tests/qemuxml2argvdata/qemuxml2argv-iothreads-disk.args

@@ -0,0 +1,17 @@
+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 2 \
+-object iothread,id=iothread1 \
+-object iothread,id=iothread2 \
+-nographic -nodefaults -monitor \
+unix:/tmp/test-monitor,server,nowait -no-acpi -boot c -usb \
+-drive file=/dev/HostVG/QEMUGuest1,if=none,id=drive-ide0-0-0 \
+-device ide-drive,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0 \
+-drive file=/var/lib/libvirt/images/iothrtest1.img,if=none,\
+id=drive-virtio-disk1 \
+-device virtio-blk-pci,iothread=iothread1,bus=pci.0,addr=0x4,\
+drive=drive-virtio-disk1,id=virtio-disk1 \
+-drive file=/var/lib/libvirt/images/iothrtest2.img,if=none,\
+id=drive-virtio-disk2 \
+-device virtio-blk-pci,iothread=iothread2,bus=pci.0,addr=0x3,\
+drive=drive-virtio-disk2,id=virtio-disk2

tests/qemuxml2argvdata/qemuxml2argv-iothreads-disk.xml

@@ -0,0 +1,40 @@
+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219136</memory>
+  <currentMemory unit='KiB'>219136</currentMemory>
+  <vcpu placement='static'>2</vcpu>
+  <iothreads>2</iothreads>
+  <os>
+    <type arch='i686' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu</emulator>
+    <disk type='block' device='disk'>
+      <driver name='qemu' type='raw'/>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='hda' bus='ide'/>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+    </disk>
+    <disk type='file' device='disk'>
+      <driver name='qemu' type='raw' iothread='1'/>
+      <source file='/var/lib/libvirt/images/iothrtest1.img'/>
+      <target dev='vdb' bus='virtio'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
+    </disk>
+    <disk type='file' device='disk'>
+      <driver name='qemu' type='raw' iothread='2'/>
+      <source file='/var/lib/libvirt/images/iothrtest2.img'/>
+      <target dev='vdc' bus='virtio'/>
+    </disk>
+    <controller type='usb' index='0'/>
+    <controller type='ide' index='0'/>
+    <controller type='pci' index='0' model='pci-root'/>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2argvtest.c

@@ -1186,6 +1186,8 @@ mymain(void)
     DO_TEST("smp", QEMU_CAPS_SMP_TOPOLOGY);
 
     DO_TEST("iothreads", QEMU_CAPS_OBJECT_IOTHREAD);
+    DO_TEST("iothreads-disk", QEMU_CAPS_OBJECT_IOTHREAD, QEMU_CAPS_DEVICE,
+            QEMU_CAPS_DRIVE);
 
     DO_TEST("cpu-topology1", QEMU_CAPS_SMP_TOPOLOGY);
     DO_TEST("cpu-topology2", QEMU_CAPS_SMP_TOPOLOGY);

tests/qemuxml2xmltest.c

@@ -302,6 +302,7 @@ mymain(void)
 
     DO_TEST("smp");
     DO_TEST("iothreads");
+    DO_TEST("iothreads-disk");
     DO_TEST("lease");
     DO_TEST("event_idx");
     DO_TEST("vhost_queues");