Added udev rules file to hot add cpu on QEMU hardware

cloud-init/41-qemu-hot-add-cpu.rules

@@ -0,0 +1,14 @@
+# On QEMU/KVM machines we want to add memory and cpus as soon as they appear
+# As of 2021-09-29, the file 40-vm-hotadd.rules does exactly the same thing for Xen and Hyper-V
+ATTR{[dmi/id]sys_vendor}=="QEMU", GOTO="vm_hotadd_apply"
+GOTO="vm_hotadd_end"
+
+LABEL="vm_hotadd_apply"
+
+# Memory hotadd request
+SUBSYSTEM=="memory", ACTION=="add", DEVPATH=="/devices/system/memory/memory[0-9]*", TEST=="state", ATTR{state}!="online", ATTR{state}="online"
+
+# CPU hotadd request
+SUBSYSTEM=="cpu", ACTION=="add", DEVPATH=="/devices/system/cpu/cpu[0-9]*", TEST=="online", ATTR{online}!="1", ATTR{online}="1"
+
+LABEL="vm_hotadd_end"