qemu: support passthrough for iscsi disks

This enables usage of commands like persistent reservations.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

src/libvirt_private.syms

@@ -156,6 +156,7 @@ virDomainDiskIoTypeToString;
 virDomainDiskPathByName;
 virDomainDiskProtocolTransportTypeFromString;
 virDomainDiskProtocolTransportTypeToString;
+virDomainDiskProtocolTypeToString;
 virDomainDiskRemove;
 virDomainDiskRemoveByName;
 virDomainDiskTypeFromString;

src/qemu/qemu_command.c

@@ -3026,7 +3026,14 @@ qemuBuildDriveDevStr(virDomainDefPtr def,
                            bus);
             goto error;
         }
-        if (disk->type != VIR_DOMAIN_DISK_TYPE_BLOCK) {
+        if (disk->type == VIR_DOMAIN_DISK_TYPE_NETWORK) {
+            if (disk->protocol != VIR_DOMAIN_DISK_PROTOCOL_ISCSI) {
+                virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                               _("disk device='lun' is not supported for protocol='%s'"),
+                               virDomainDiskProtocolTypeToString(disk->protocol));
+                goto error;
+            }
+        } else if (disk->type != VIR_DOMAIN_DISK_TYPE_BLOCK) {
             virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
                            _("disk device='lun' is not supported for type='%s'"),
                            virDomainDiskTypeToString(disk->type));

tests/qemuxml2argvdata/qemuxml2argv-disk-drive-network-iscsi-lun.args

+LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test \
+/usr/bin/qemu -S -M pc -m 214 -smp 1 -nographic -nodefconfig -nodefaults \
+-monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot c \
+-device virtio-scsi-pci,id=scsi0,bus=pci.0,addr=0x3 -usb \
+-drive file=iscsi://example.org:3260/iqn.1992-01.com.example,if=none,\
+id=drive-scsi0-0-0-0,format=raw -device scsi-block,bus=scsi0.0,channel=0,\
+scsi-id=0,lun=0,drive=drive-scsi0-0-0-0,id=scsi0-0-0-0

tests/qemuxml2argvdata/qemuxml2argv-disk-drive-network-iscsi-lun.xml

+<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'>1</vcpu>
+  <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='network' device='lun'>
+      <driver name='qemu' type='raw'/>
+      <source protocol='iscsi' name='iqn.1992-01.com.example'>
+        <host name='example.org' port='3260'/>
+      </source>
+      <target dev='sda' bus='scsi'/>
+    </disk>
+    <controller type='usb' index='0'/>
+    <controller type='scsi' index='0' model='virtio-scsi'/>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2argvtest.c

@@ -503,6 +503,10 @@ mymain(void)
             QEMU_CAPS_DRIVE, QEMU_CAPS_DRIVE_FORMAT);
     DO_TEST("disk-drive-network-iscsi",
             QEMU_CAPS_DRIVE, QEMU_CAPS_DRIVE_FORMAT);
+    DO_TEST("disk-drive-network-iscsi-lun",
+            QEMU_CAPS_DRIVE, QEMU_CAPS_DEVICE, QEMU_CAPS_DRIVE_FORMAT,
+            QEMU_CAPS_NODEFCONFIG, QEMU_CAPS_VIRTIO_SCSI,
+            QEMU_CAPS_VIRTIO_BLK_SG_IO, QEMU_CAPS_SCSI_BLOCK);
     DO_TEST("disk-drive-network-gluster",
             QEMU_CAPS_DRIVE, QEMU_CAPS_DRIVE_FORMAT);
     DO_TEST("disk-drive-network-rbd",