Don't require Xen to get VM stats

It's not completely Xen agnostic because then it would not be possible
to query stubdomains, as libvirt is not aware of them. On the other
hand, non-Xen has one more API method working.

When not using Xen, construct the dictionary as "xc.domain_getinfo()"
would, so the info loop can consume from both inputs.

Author: ben-grande

qubes/app.py

@@ -417,17 +417,44 @@ def get_vm_stats(self, previous_time=None, previous=None, only_vm=None):
 
         current_time = time.time()
         current = {}
-        if not self.app.vmm.is_xen:
-            raise NotImplementedError("This function requires Xen hypervisor")
         if only_vm:
             xid = only_vm.xid
             if xid < 0:
                 raise qubes.exc.QubesVMNotRunningError(only_vm)
-            info = self.app.vmm.xc.domain_getinfo(xid, 1)
-            if info[0]["domid"] != xid:
-                raise qubes.exc.QubesVMNotRunningError(only_vm)
+            if self.app.vmm.is_xen:
+                info = self.app.vmm.xc.domain_getinfo(xid, 1)
+                if info[0]["domid"] != xid:
+                    raise qubes.exc.QubesVMNotRunningError(only_vm)
+            else:
+                if not only_vm.libvirt_domain:
+                    raise qubes.exc.QubesVMNotRunningError(only_vm)
+                dom_info = only_vm.libvirt_domain.info()
+                info = [
+                    {
+                        "domid": only_vm.xid,
+                        "mem_kb": dom_info[2],
+                        "online_vcpus": dom_info[3],
+                        "cpu_time": dom_info[4],
+                    }
+                ]
         else:
-            info = self.app.vmm.xc.domain_getinfo(0, 1024)
+            if self.app.vmm.is_xen:
+                info = self.app.vmm.xc.domain_getinfo(0, 1024)
+            else:
+                running = self.app.vmm.libvirt_conn.listAllDomains(
+                    libvirt.VIR_CONNECT_GET_ALL_DOMAINS_STATS_ACTIVE
+                )
+                info = []
+                for dom in running:
+                    dom_info = dom.info()
+                    dom_info_dict = {
+                        "domid": dom.ID(),
+                        "mem_kb": dom_info[2],
+                        "online_vcpus": dom_info[3],
+                        "cpu_time": dom_info[4],
+                    }
+                    info.append(dom_info_dict)
+
         # TODO: add stubdomain stats to actual VMs
         for vm in info:
             domid = vm["domid"]