[KVM] Allow passing the OS type machine for KVM XML domains through VM setting (#11569)

* [KVM] Allow passing OS type machine to XML domains

Author: nvazquez

api/src/main/java/com/cloud/vm/VmDetailConstants.java

@@ -41,6 +41,7 @@ public interface VmDetailConstants {
     String KVM_VNC_PORT = "kvm.vnc.port";
     String KVM_VNC_ADDRESS = "kvm.vnc.address";
     String KVM_VNC_PASSWORD = "kvm.vnc.password";
+    String KVM_GUEST_OS_MACHINE_TYPE = "kvm.guest.os.machine.type";
 
     // KVM specific, custom virtual GPU hardware
     String VIDEO_HARDWARE = "video.hardware";

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

@@ -3306,6 +3306,9 @@ protected GuestDef createGuestFromSpec(VirtualMachineTO vmTO, LibvirtVMDef vm, S
                 }
             }
             guest.setIothreads(customParams.containsKey(VmDetailConstants.IOTHREADS));
+            if (customParams.containsKey(VmDetailConstants.KVM_GUEST_OS_MACHINE_TYPE)) {
+                guest.setMachineType(customParams.get(VmDetailConstants.KVM_GUEST_OS_MACHINE_TYPE));
+            }
         }
         guest.setUuid(uuid);
         if(!isGuestS390x()) {