Re: [Qemu-devel] [PATCH V2 2/2] arm: virt: add PMU property to machvirt machine type

[Wei Huang <wei@redhat.com>]

On 09/14/2016 03:37 AM, Andrew Jones wrote:
> On Wed, Sep 14, 2016 at 02:09:03AM -0400, Wei Huang wrote:
>> CPU vPMU is now turned off by default, but it was ON in 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 on in
>> virt-2.7 machine type to make sure it is backward compatible.
>>
>> Signed-off-by: Wei Huang <wei@redhat.com>
>> ---
>>  hw/arm/virt.c | 12 ++++++++++++
>>  1 file changed, 12 insertions(+)
>>
>> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
>> index a781ad0..83cfea7 100644
>> --- a/hw/arm/virt.c
>> +++ b/hw/arm/virt.c
>> @@ -91,6 +91,7 @@ typedef struct {
>>      bool secure;
>>      bool highmem;
>>      int32_t gic_version;
>> +    bool pmu;
>>  } VirtMachineState;
> 
> The compat bool doesn't need to be in machine state, so it should
> be in the class. See 'disallow_affinity_adjustment' in VirtMachineClass
> for an example of a adding a compat bool for a different reason. Also,
> I'd name it something like pmu_default_on.

This should be an easy fix.

> 
>>  
>>  #define TYPE_VIRT_MACHINE   MACHINE_TYPE_NAME("virt")
>> @@ -1317,6 +1318,11 @@ static void machvirt_init(MachineState *machine)
>>              }
>>          }
>>  
>> +        if (vms->pmu) {
>> +            /* Note: the property name is "pmu", not "has_pmu" */
> 
> The comment is unnecessary. Please remove.
> 

I might still say something here. :-) The reason is the confusion of
"pmu" as a command line property and "has_pmu" as a property of ARMCPU.
Most other properties use the same naming, so they are OK. But PMU, due
to naming difference, did cause trouble for me and took a while to debug.

>> +            object_property_set_bool(cpuobj, true, "pmu", NULL);
>> +        }
>> +
>>          if (object_property_find(cpuobj, "reset-cbar", NULL)) {
>>              object_property_set_int(cpuobj, vbi->memmap[VIRT_CPUPERIPHS].base,
>>                                      "reset-cbar", &error_abort);
>> @@ -1510,6 +1516,8 @@ static void virt_2_7_instance_init(Object *obj)
>>      object_property_set_description(obj, "gic-version",
>>                                      "Set GIC version. "
>>                                      "Valid values are 2, 3 and host", NULL);
>> +    /* Default PMU is on for 2.7 */
> 
> This comment is unnecessary. Please remove.

OK

> 
>> +    vms->pmu = true;
>>  }
>>  
>>  static void virt_machine_2_7_options(MachineClass *mc)
>> @@ -1522,7 +1530,11 @@ DEFINE_VIRT_MACHINE_AS_LATEST(2, 7)
>>  
>>  static void virt_2_6_instance_init(Object *obj)
>>  {
>> +    VirtMachineState *vms = VIRT_MACHINE(obj);
>> +
>>      virt_2_7_instance_init(obj);
>> +    /* Default PMU is off for 2.6 */
>> +    vms->pmu = false;
> 
> You shouldn't need to touch 2.6 code. The compat bool is false
> by default (BSS init), which is the correct value for every
> machine type, except the 2.7 machine type.

I will fix the comments, using the next email from you.

> 
>>  }
>>  
>>  static void virt_machine_2_6_options(MachineClass *mc)
>> -- 
>> 1.8.3.1
>>
>>
> 
> Thanks,
> drew
>