kvm_stat: Abstract ioctl numbers

Unfortunately ioctl numbers are platform specific, so abstract them out
of the code so they can be overridden. As it happens x86 and s390 share
the same values, so nothing needs to change yet.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

scripts/kvm/kvm_stat

@@ -177,6 +177,12 @@ x86_exit_reasons = {
 sc_perf_evt_open = None
 exit_reasons = None
 
+ioctl_numbers = {
+    'SET_FILTER' : 0x40082406,
+    'ENABLE'     : 0x00002400,
+    'DISABLE'    : 0x00002401,
+}
+
 def x86_init(flag):
     globals().update({
         'sc_perf_evt_open' : 298,
@@ -301,14 +307,14 @@ class Event(object):
             raise Exception('perf_event_open failed')
         if filter:
             import fcntl
-            fcntl.ioctl(fd, 0x40082406, filter)
+            fcntl.ioctl(fd, ioctl_numbers['SET_FILTER'], filter)
         self.fd = fd
     def enable(self):
         import fcntl
-        fcntl.ioctl(self.fd, 0x00002400, 0)
+        fcntl.ioctl(self.fd, ioctl_numbers['ENABLE'], 0)
     def disable(self):
         import fcntl
-        fcntl.ioctl(self.fd, 0x00002401, 0)
+        fcntl.ioctl(self.fd, ioctl_numbers['DISABLE'], 0)
 
 class TracepointProvider(object):
     def __init__(self):