Re: [Qemu-devel] [PATCH v6 02/17] Add accelerator id and model name to CPUState

[Eduardo Habkost]

On Mon, Apr 27, 2015 at 04:53:16PM +0200, Michael Mueller wrote:
> The patch defines ids per accelerator and adds the accel_id and
> the model_name to the CPUState. The accel_id is initialized by
> common code, the model name needs to be initialized by target
> specific code.
> 
> Signed-off-by: Michael Mueller <address@hidden>
> Acked-by: Christian Borntraeger <address@hidden>
> ---
>  include/qom/cpu.h |  5 +++++
>  qapi-schema.json  |  9 +++++++++
>  qom/cpu.c         | 14 ++++++++++++++
>  3 files changed, 28 insertions(+)
> 
> diff --git a/include/qom/cpu.h b/include/qom/cpu.h
> index 9dafb48..4ffc050 100644
> --- a/include/qom/cpu.h
> +++ b/include/qom/cpu.h
> @@ -236,6 +236,8 @@ struct kvm_run;
>   * @mem_io_pc: Host Program Counter at which the memory was accessed.
>   * @mem_io_vaddr: Target virtual address at which the memory was accessed.
>   * @kvm_fd: vCPU file descriptor for KVM.
> + * @accel_id: accelerator id of this CPU.
> + * @model_name: model name of this CPU
>   *
>   * State of one CPU core or thread.
>   */
> @@ -313,6 +315,9 @@ struct CPUState {
>         (absolute value) offset as small as possible.  This reduces code
>         size, especially for hosts without large memory offsets.  */
>      volatile sig_atomic_t tcg_exit_req;
> +
> +    AccelId accel_id;

This can be a AccelState pointer, set on initialization, because we have
another user case for having a AccelState pointer: query-cpu-definition
implementations may create temporary CPU objects with a different accel
object to be able to probe for accel-specific data.

(The pointer may become a link QOM property later.)


> +    char *model_name;
>  };
>  
>  QTAILQ_HEAD(CPUTailQ, CPUState);
> diff --git a/qapi-schema.json b/qapi-schema.json
> index ac9594d..540e520 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -2515,6 +2515,15 @@
>  ##
>  { 'command': 'query-machines', 'returns': ['MachineInfo'] }
>  
> +# @AccelId
> +#
> +# Defines accelerator ids
> +#
> +# Since: 2.4
> +##
> +{ 'enum': 'AccelId',
> +  'data': ['qtest', 'tcg', 'kvm', 'xen'] }
> +

Not sure if it is better to have an enum or simply a string here.

>  ##
>  # @CpuDefinitionInfo:
>  #
> diff --git a/qom/cpu.c b/qom/cpu.c
> index 108bfa2..457afc7 100644
> --- a/qom/cpu.c
> +++ b/qom/cpu.c
> @@ -67,6 +67,20 @@ CPUState *cpu_generic_init(const char *typename, const 
> char *cpu_model)
>          goto out;
>      }
>  
> +    if (tcg_enabled()) {
> +        cpu->accel_id = ACCEL_ID_TCG;
> +    } else if (kvm_enabled()) {
> +        cpu->accel_id = ACCEL_ID_KVM;
> +    }
> +#ifdef CONFIG_XEN
> +    else if (xen_enabled()) {
> +        cpu->accel_id = ACCEL_ID_XEN;
> +    }
> +#endif
> +    else {
> +        cpu->accel_id = ACCEL_ID_QTEST;
> +    }

You can simply use ACCEL_GET_CLASS(current_machine->accelerator)->name
here. If we really want an enum, we can add an AccelId field to
AccelClass, and initialize it properly on the accel class_init
functions.

CONFIG_USER may require some special code when returning the accelerator
ID as "tcg" because IIRC it doesn't use the QOM accel classes (yet).

> +
>      object_property_set_bool(OBJECT(cpu), true, "realized", &err);
>  
>  out:
> -- 
> 1.8.3.1
> 

-- 
Eduardo