Re: [Qemu-devel] [PATCH V3 2/2] arm: virt: add PMU property to mach-virt machine type

[Andrew Jones]

On Thu, Sep 15, 2016 at 01:04:16AM -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 <address@hidden>
> ---
>  hw/arm/virt.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index a781ad0..a3fc454 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -84,6 +84,7 @@ typedef struct {
>      MachineClass parent;
>      VirtBoardInfo *daughterboard;
>      bool disallow_affinity_adjustment;
> +    bool pmu_default_on;
>  } VirtMachineClass;
>  
>  typedef struct {
> @@ -1317,6 +1318,11 @@ static void machvirt_init(MachineState *machine)
>              }
>          }
>  
> +        if (vmc->pmu_default_on) {
> +            /* Property name is "pmu", defined in arm_cpu_has_pmu_property */

I still don't see the point of this comment. The code below sets the
property named "pmu", so we know the property name is "pmu" based on
that.

> +            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);
> @@ -1514,6 +1520,9 @@ static void virt_2_7_instance_init(Object *obj)
>  
>  static void virt_machine_2_7_options(MachineClass *mc)
>  {
> +    VirtMachineClass *vmc = VIRT_MACHINE_CLASS(OBJECT_CLASS(mc));
> +
> +    vmc->pmu_default_on = true;
>  }
>  DEFINE_VIRT_MACHINE_AS_LATEST(2, 7)
>  
> @@ -1532,5 +1541,9 @@ 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 and down as PMU support was first introduced
> +     * and enabled in 2.7.
> +     */
> +    vmc->pmu_default_on = false;
>  }
>  DEFINE_VIRT_MACHINE(2, 6)
> -- 
> 1.8.3.1
> 
>

Otherwise,

Reviewed-by: Andrew Jones <address@hidden>