tools/kvm_stat: display guest list in pid/guest selection screens

Display a (possibly inaccurate) list of all running guests. Note that we
leave a bit of extra room above the list for potential error messages.
Furthermore, we deliberately do not reject pids or guest names that are
not in our list, as we cannot rule out that our fuzzy approach might be
in error somehow.
Signed-off-by: Stefan Raspl <raspl@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/kvm/kvm_stat/kvm_stat

@@ -894,15 +894,9 @@ class Tui(object):
             curses.nocbreak()
             curses.endwin()
 
-    @staticmethod
-    def get_pid_from_gname(gname):
-        """Fuzzy function to convert guest name to QEMU process pid.
-
-        Returns a list of potential pids, can be empty if no match found.
-        Throws an exception on processing errors.
-
-        """
-        pids = []
+    def get_all_gnames(self):
+        """Returns a list of (pid, gname) tuples of all running guests"""
+        res = []
         try:
             child = subprocess.Popen(['ps', '-A', '--format', 'pid,args'],
                                      stdout=subprocess.PIPE)
@@ -912,11 +906,40 @@ class Tui(object):
             line = line.lstrip().split(' ', 1)
             # perform a sanity check before calling the more expensive
             # function to possibly extract the guest name
-            if (' -name ' in line[1] and
-                    gname == self.get_gname_from_pid(line[0])):
-                pids.append(int(line[0]))
+            if ' -name ' in line[1]:
+                res.append((line[0], self.get_gname_from_pid(line[0])))
         child.stdout.close()
 
+        return res
+
+    def print_all_gnames(self, row):
+        """Print a list of all running guests along with their pids."""
+        self.screen.addstr(row, 2, '%8s  %-60s' %
+                           ('Pid', 'Guest Name (fuzzy list, might be '
+                            'inaccurate!)'),
+                           curses.A_UNDERLINE)
+        row += 1
+        try:
+            for line in self.get_all_gnames():
+                self.screen.addstr(row, 2, '%8s  %-60s' % (line[0], line[1]))
+                row += 1
+                if row >= self.screen.getmaxyx()[0]:
+                    break
+        except Exception:
+            self.screen.addstr(row + 1, 2, 'Not available')
+
+    def get_pid_from_gname(self, gname):
+        """Fuzzy function to convert guest name to QEMU process pid.
+
+        Returns a list of potential pids, can be empty if no match found.
+        Throws an exception on processing errors.
+
+        """
+        pids = []
+        for line in self.get_all_gnames():
+            if gname == line[1]:
+                pids.append(int(line[0]))
+
         return pids
 
     @staticmethod
@@ -1102,6 +1125,7 @@ class Tui(object):
                                'This might limit the shown data to the trace '
                                'statistics.')
             self.screen.addstr(5, 0, msg)
+            self.print_all_gnames(7)
 
             curses.echo()
             self.screen.addstr(3, 0, "Pid [0 or pid]: ")
@@ -1171,6 +1195,7 @@ class Tui(object):
                                'This might limit the shown data to the trace '
                                'statistics.')
             self.screen.addstr(5, 0, msg)
+            self.print_all_gnames()
             curses.echo()
             self.screen.addstr(3, 0, "Guest [ENTER or guest]: ")
             gname = self.screen.getstr()