scripts/kvm/kvm_stat: Cleanup of platform detection

s390 machines can also be detected via uname -m, i.e. python's
os.uname, no need for more complicated checks.

Calling uname once and saving its value for multiple checks is
perfectly sufficient. We don't expect the machine's architecture to
change when the script is running anyway.

On multi-cpu systems x86_init currently will get called multiple
times, returning makes sure we don't waste cicles on that.
Signed-off-by: NJanosch Frank <frankja@linux.vnet.ibm.com>
Message-Id: <1452525484-32309-16-git-send-email-frankja@linux.vnet.ibm.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

scripts/kvm/kvm_stat

@@ -254,24 +254,21 @@ def aarch64_init():
     EXIT_REASONS = AARCH64_EXIT_REASONS
 
 def detect_platform():
-    if os.uname()[4].startswith('ppc'):
+    machine = os.uname()[4]
+
+    if machine.startswith('ppc'):
         ppc_init()
-        return
-    elif os.uname()[4].startswith('aarch64'):
+    elif machine.startswith('aarch64'):
         aarch64_init()
-        return
-
-    for line in file('/proc/cpuinfo').readlines():
-        if line.startswith('flags'):
-            for flag in line.split():
-                if flag in X86_EXIT_REASONS:
-                    x86_init(flag)
-                    return
-        elif line.startswith('vendor_id'):
-            for flag in line.split():
-                if flag == 'IBM/S390':
-                    s390_init()
-                    return
+    elif machine.startswith('s390'):
+        s390_init()
+    else:
+        for line in file('/proc/cpuinfo').readlines():
+            if line.startswith('flags'):
+                for flag in line.split():
+                    if flag in X86_EXIT_REASONS:
+                        x86_init(flag)
+                        return
 
 
 def walkdir(path):