Re: [RFC PATCH RESEND 2/4] target/arm/kvm: Add QAPI struct ArmTargetImplCPU

[Eric Auger <eric.auger@redhat.com>]

Hi Shameer,

On 8/1/25 9:47 AM, Shameer Kolothum wrote:
> From: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
>
> Introduce a QAPI‐defined struct (and its array) for target implementation
> CPUs. This enables specifying target implementation CPU parameters
> via -machine, for example:
>
> -M virt, \
>   impl-cpu.0.midr=1,impl-cpu.0.revidr=1,impl-cpu.0.aidr=1, \
>   impl-cpu.1.midr=2,impl-cpu.1.revidr=2,impl-cpu.1.aidr=0
>
> Subsequent patch will make use of this by using object_property_add(),
> allowing users to configure each target CPU’s midr, revidr, and aidr
> fields directly from the command line.
>
> While at it, also provide a helper function to set the target CPUs.
>
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> ---
>  qapi/machine.json    | 34 ++++++++++++++++++++++++++++++++++
>  target/arm/kvm.c     | 16 ++++++++++++++++
>  target/arm/kvm_arm.h |  8 ++++++++
>  3 files changed, 58 insertions(+)
>
> diff --git a/qapi/machine.json b/qapi/machine.json
> index a6b8795b09..d6e0e3b2e3 100644
> --- a/qapi/machine.json
> +++ b/qapi/machine.json
> @@ -1898,3 +1898,37 @@
>  { 'command': 'x-query-interrupt-controllers',
>    'returns': 'HumanReadableText',
>    'features': [ 'unstable' ]}
> +
> +##
> +# @ArmTargetImplCPU:
> +#
> +# Info for a single target implementation CPU.
> +#
> +# @midr: MIDR value
> +# @revidr: REVIDR value
> +# @aidr: AIDR value
> +#
> +# Since: 10.2
> +##
> +{ 'struct': 'ArmTargetImplCPU',
> +  'data': {
> +    'midr': 'uint64',
> +    'revidr': 'uint64',
> +    'aidr': 'uint64'
> +  }
> +}
> +
> +##
> +# @ArmTargetImplCPUs:
> +#
> +# List of target implementation CPUs.
> +#
> +# @target-cpus: List of ArmTargetImplCPU entries.
> +#
> +# Since: 10.2
> +##
> +{ 'struct': 'ArmTargetImplCPUs',
> +  'data': {
> +    'target-cpus': ['ArmTargetImplCPU']
> +  }
> +}
> diff --git a/target/arm/kvm.c b/target/arm/kvm.c
> index eb04640b50..8f325c4ca4 100644
> --- a/target/arm/kvm.c
> +++ b/target/arm/kvm.c
> @@ -66,6 +66,9 @@ typedef struct ARMHostCPUFeatures {
>  
>  static ARMHostCPUFeatures arm_host_cpu_features;
>  
> +static uint64_t target_impl_cpus_num;
> +static ArmTargetImplCPU *target_impl_cpus;
> +
>  /**
>   * kvm_arm_vcpu_init:
>   * @cpu: ARMCPU
> @@ -2816,3 +2819,16 @@ void kvm_arm_enable_mte(Object *cpuobj, Error **errp)
>          cpu->kvm_mte = true;
>      }
>  }
> +
> +bool kvm_arm_set_target_impl_cpus(uint64_t num, ArmTargetImplCPU *cpus)
> +{
> +
> +    if (target_impl_cpus_num) {
> +        return false;
> +    }
> +
> +    target_impl_cpus_num = num;
> +    target_impl_cpus = cpus;
see my question on 4/4 wrt array.

Eric
> +
> +    return true;
> +}
> diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h
> index 3cd6447901..8754302333 100644
> --- a/target/arm/kvm_arm.h
> +++ b/target/arm/kvm_arm.h
> @@ -244,6 +244,8 @@ void kvm_arm_enable_mte(Object *cpuobj, Error **errp);
>  
>  int kvm_arm_get_writable_id_regs(ARMCPU *cpu, IdRegMap *idregmap);
>  
> +bool kvm_arm_set_target_impl_cpus(uint64_t num, ArmTargetImplCPU *cpus);
> +
>  #else
>  
>  /*
> @@ -280,6 +282,12 @@ static inline int kvm_arm_get_writable_id_regs(ARMCPU *cpu, IdRegMap *idregmap)
>      return -ENOSYS;
>  }
>  
> +static inline
> +bool kvm_arm_set_target_impl_cpus(uint64_t num, ArmTargetImplCPU *cpus)
> +{
> +    return false;
> +}
> +
>  /*
>   * These functions should never actually be called without KVM support.
>   */