Re: [PATCH v2 02/11] hw/boards: Introduce machine_class_valid_for_accelerator()

[Cornelia Huck <cohuck@xxxxxxxxxx>]

On Fri, 19 Feb 2021 18:38:38 +0100
Philippe Mathieu-Daudé <philmd@xxxxxxxxxx> wrote:

> Introduce the valid_accelerators[] field to express the list
> of valid accelators a machine can use, and add the
> machine_class_valid_for_current_accelerator() and
> machine_class_valid_for_accelerator() methods.
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>
> ---
>  include/hw/boards.h | 24 ++++++++++++++++++++++++
>  hw/core/machine.c   | 26 ++++++++++++++++++++++++++
>  2 files changed, 50 insertions(+)
> 
> diff --git a/include/hw/boards.h b/include/hw/boards.h
> index 68d3d10f6b0..4d08bc12093 100644
> --- a/include/hw/boards.h
> +++ b/include/hw/boards.h
> @@ -36,6 +36,24 @@ void machine_set_cpu_numa_node(MachineState *machine,
>                                 const CpuInstanceProperties *props,
>                                 Error **errp);
>  
> +/**
> + * machine_class_valid_for_accelerator:
> + * @mc: the machine class
> + * @acc_name: accelerator name
> + *
> + * Returns %true if the accelerator is valid for the machine, %false
> + * otherwise. See #MachineClass.valid_accelerators.

Naming confusion: is the machine class valid for the accelerator, or
the accelerator valid for the machine class? Or either? :)

> + */
> +bool machine_class_valid_for_accelerator(MachineClass *mc, const char 
> *acc_name);
> +/**
> + * machine_class_valid_for_current_accelerator:
> + * @mc: the machine class
> + *
> + * Returns %true if the accelerator is valid for the current machine,
> + * %false otherwise. See #MachineClass.valid_accelerators.

Same here: current accelerator vs. current machine.

> + */
> +bool machine_class_valid_for_current_accelerator(MachineClass *mc);
> +
>  void machine_class_allow_dynamic_sysbus_dev(MachineClass *mc, const char 
> *type);
>  /*
>   * Checks that backend isn't used, preps it for exclusive usage and
> @@ -125,6 +143,11 @@ typedef struct {
>   *    should instead use "unimplemented-device" for all memory ranges where
>   *    the guest will attempt to probe for a device that QEMU doesn't
>   *    implement and a stub device is required.
> + * @valid_accelerators:
> + *    If this machine supports a specific set of virtualization accelerators,
> + *    this contains a NULL-terminated list of the accelerators that can be
> + *    used. If this field is not set, any accelerator is valid. The QTest
> + *    accelerator is always valid.
>   * @kvm_type:
>   *    Return the type of KVM corresponding to the kvm-type string option or
>   *    computed based on other criteria such as the host kernel capabilities
> @@ -166,6 +189,7 @@ struct MachineClass {
>      const char *alias;
>      const char *desc;
>      const char *deprecation_reason;
> +    const char *const *valid_accelerators;
>  
>      void (*init)(MachineState *state);
>      void (*reset)(MachineState *state);
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index 970046f4388..c42d8e382b1 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -518,6 +518,32 @@ static void machine_set_nvdimm_persistence(Object *obj, 
> const char *value,
>      nvdimms_state->persistence_string = g_strdup(value);
>  }
>  
> +bool machine_class_valid_for_accelerator(MachineClass *mc, const char 
> *acc_name)
> +{
> +    const char *const *name = mc->valid_accelerators;
> +
> +    if (!name) {
> +        return true;
> +    }
> +    if (strcmp(acc_name, "qtest") == 0) {
> +        return true;
> +    }
> +
> +    for (unsigned i = 0; name[i]; i++) {
> +        if (strcasecmp(acc_name, name[i]) == 0) {
> +            return true;
> +        }
> +    }
> +    return false;
> +}
> +
> +bool machine_class_valid_for_current_accelerator(MachineClass *mc)
> +{
> +    AccelClass *ac = ACCEL_GET_CLASS(current_accel());
> +
> +    return machine_class_valid_for_accelerator(mc, ac->name);
> +}

The implementation of the function tests for the current accelerator,
so I think you need to tweak the description above?

> +
>  void machine_class_allow_dynamic_sysbus_dev(MachineClass *mc, const char 
> *type)
>  {
>      QAPI_LIST_PREPEND(mc->allowed_dynamic_sysbus_devices, g_strdup(type));