arm: virt: add PMU property to mach-virt machine type

CPU vPMU is now turned ON by default, but this feature wasn't introduced
until virt-2.7 machine type. To solve this problem, this patch adds a
PMU option in machine state, which is used to control CPU's vPMU status.
This PMU option is not exposed to command line and is turned off in
virt-2.6 machine type.

Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Wei Huang <wei@redhat.com>
Message-id: 1477463301-17175-3-git-send-email-wei@redhat.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/arm/virt.c

@@ -85,6 +85,7 @@ typedef struct {
     VirtBoardInfo *daughterboard;
     bool disallow_affinity_adjustment;
     bool no_its;
+    bool no_pmu;
 } VirtMachineClass;
 
 typedef struct {
@@ -1353,6 +1354,10 @@ static void machvirt_init(MachineState *machine)
             }
         }
 
+        if (vmc->no_pmu && object_property_find(cpuobj, "pmu", NULL)) {
+            object_property_set_bool(cpuobj, false, "pmu", NULL);
+        }
+
         if (object_property_find(cpuobj, "reset-cbar", NULL)) {
             object_property_set_int(cpuobj, vbi->memmap[VIRT_CPUPERIPHS].base,
                                     "reset-cbar", &error_abort);
@@ -1592,5 +1597,7 @@ static void virt_machine_2_6_options(MachineClass *mc)
     virt_machine_2_7_options(mc);
     SET_MACHINE_COMPAT(mc, VIRT_COMPAT_2_6);
     vmc->disallow_affinity_adjustment = true;
+    /* Disable PMU for 2.6 as PMU support was first introduced in 2.7 */
+    vmc->no_pmu = true;
 }
 DEFINE_VIRT_MACHINE(2, 6)