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

[Andrew Jones <drjones@redhat.com>]

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.

>  
>  #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.

> +            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.

> +    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.

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

Thanks,
drew