kvm: add SCSI controllers based on the number of virtio-SCSI disks (apache#9823)

According to libvirt code, the units per scsi controller is set to 7
therefore, we need to create scsi controller every 7 disks (including CDROM).

https://github.com/libvirt/libvirt/blob/50cc7a0d9d2b9df085ec073a6d60820a9642158a/src/conf/domain_conf.h#L3007-L3008

https://github.com/libvirt/libvirt/blob/50cc7a0d9d2b9df085ec073a6d60820a9642158a/src/conf/domain_conf.c#L6701-L6704

Author: weizhouapache

plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/resource/LibvirtComputingResource.java

@@ -2916,9 +2916,7 @@ protected DevicesDef createDevicesDef(VirtualMachineTO vmTO, GuestDef guest, int
 
             int socket = getCoresPerSocket(vcpus, details);
             boolean isIothreadsEnabled = details != null && details.containsKey(VmDetailConstants.IOTHREADS);
-            for (int i = 0; i < socket; i++) {
-                devices.addDevice(createSCSIDef(i, i, vcpus, isIothreadsEnabled));
-            }
+            addSCSIControllers(devices, vcpus, vmTO.getDisks().length, isIothreadsEnabled);
         }
 
 
@@ -2979,20 +2977,19 @@ protected ChannelDef createChannelDef(VirtualMachineTO vmTO) {
      * Creates Virtio SCSI controller. <br>
      * The respective Virtio SCSI XML definition is generated only if the VM's Disk Bus is of ISCSI.
      */
-    protected SCSIDef createSCSIDef(int index, int function ,int vcpus) {
-        return new SCSIDef((short)index, 0, 0, 9, function, vcpus);
-    }
-
-    protected SCSIDef createSCSIDef(int vcpus) {
-        return new SCSIDef((short)0, 0, 0, 9, 0, vcpus);
+    protected SCSIDef createSCSIDef(short index, int vcpus, boolean isIothreadsEnabled) {
+        return new SCSIDef(index, 0, 0, 9 + index, 0, vcpus, isIothreadsEnabled);
     }
 
-    protected SCSIDef createSCSIDef(int index, int function, int vcpus, boolean isIothreadsEnabled) {
-        return new SCSIDef((short)index, 0, 0, 9, function, vcpus, isIothreadsEnabled);
-    }
 
-    protected SCSIDef createSCSIDef(int vcpus, boolean isIothreadsEnabled) {
-        return new SCSIDef((short)0, 0, 0, 9, 0, vcpus, isIothreadsEnabled);
+    private void addSCSIControllers(DevicesDef devices, int vcpus, int diskCount, boolean isIothreadsEnabled) {
+        int controllers = diskCount / 7;
+        if (diskCount % 7 != 0) {
+            controllers++;
+        }
+        for (int i = 0; i < controllers; i++) {
+            devices.addDevice(createSCSIDef((short)i, vcpus, isIothreadsEnabled));
+        }
     }
 
     protected ConsoleDef createConsoleDef() {