[PATCH v5 2/6] target-arm: kvm: save/restore mp state

[Peter Maydell]

On 23 March 2015 at 17:05, Alex Bennée <alex.bennee at linaro.org> wrote:
> This adds the saving and restore of the current Multi-Processing state
> of the machine. While the KVM_GET/SET_MP_STATE API exposes a number of
> potential states for x86 we only use two for ARM. Either the process is
> running or not. We then save this state into the cpu_powered TCG state
> to avoid changing the serialisation format.
>
> Signed-off-by: Alex Bennée <alex.bennee at linaro.org>
>
> ---
> v2
>   - make mpstate field runtime dependant (kvm_enabled())
>   - drop initial KVM_CAP_MP_STATE requirement
>   - re-use cpu_powered instead of new field
>
> v4
>   - s/HALTED/STOPPED/
>   - move code from machine.c to kvm.
>
> diff --git a/target-arm/kvm.c b/target-arm/kvm.c
> index 72c1fa1..a74832c 100644
> --- a/target-arm/kvm.c
> +++ b/target-arm/kvm.c
> @@ -458,6 +458,46 @@ void kvm_arm_reset_vcpu(ARMCPU *cpu)
>      }
>  }
>
> +/*
> + * Update KVM's MP_STATE based on what QEMU thinks it is
> + */
> +int kvm_arm_sync_mpstate_to_kvm(ARMCPU *cpu)
> +{
> +    if (kvm_check_extension(CPU(cpu)->kvm_state, KVM_CAP_MP_STATE)) {

Doing the ioctl to check the extension every time isn't great.
Look at the way ppc and s390 do a cap check at init time and
cache the answer.

> +        struct kvm_mp_state mp_state = {
> +            .mp_state =
> +            cpu->powered_off ? KVM_MP_STATE_STOPPED : KVM_MP_STATE_RUNNABLE
> +        };
> +        int ret = kvm_vcpu_ioctl(CPU(cpu), KVM_SET_MP_STATE, &mp_state);
> +        if (ret) {
> +            fprintf(stderr, "%s: failed to set MP_STATE %d/%s\n",
> +                    __func__, ret, strerror(ret));
> +            return -1;
> +        }
> +    }
> +
> +    return 0;
> +}
> +
> +/*
> + * Sync the KVM MP_STATE into QEMU
> + */
> +int kvm_arm_sync_mpstate_to_qemu(ARMCPU *cpu)
> +{
> +    if (kvm_check_extension(CPU(cpu)->kvm_state, KVM_CAP_MP_STATE)) {
> +        struct kvm_mp_state mp_state;
> +        int ret = kvm_vcpu_ioctl(CPU(cpu), KVM_GET_MP_STATE, &mp_state);
> +        if (ret) {
> +            fprintf(stderr, "%s: failed to get MP_STATE %d/%s\n",
> +                    __func__, ret, strerror(ret));
> +            abort();
> +        }
> +        cpu->powered_off = (mp_state.mp_state == KVM_MP_STATE_STOPPED);
> +    }
> +
> +    return 0;
> +}
> +
>  void kvm_arch_pre_run(CPUState *cs, struct kvm_run *run)
>  {
>  }
> diff --git a/target-arm/kvm32.c b/target-arm/kvm32.c
> index 94030d1..49b6bab 100644
> --- a/target-arm/kvm32.c
> +++ b/target-arm/kvm32.c
> @@ -356,6 +356,8 @@ int kvm_arch_put_registers(CPUState *cs, int level)
>          return EINVAL;
>      }
>
> +    kvm_arm_sync_mpstate_to_kvm(cpu);
> +
>      return ret;
>  }
>
> @@ -427,5 +429,7 @@ int kvm_arch_get_registers(CPUState *cs)
>       */
>      write_list_to_cpustate(cpu);
>
> +    kvm_arm_sync_mpstate_to_qemu(cpu);
> +
>      return 0;
>  }
> diff --git a/target-arm/kvm64.c b/target-arm/kvm64.c
> index 8cf3a62..fed03f2 100644
> --- a/target-arm/kvm64.c
> +++ b/target-arm/kvm64.c
> @@ -211,6 +211,8 @@ int kvm_arch_put_registers(CPUState *cs, int level)
>          return EINVAL;
>      }
>
> +    kvm_arm_sync_mpstate_to_kvm(cpu);
> +
>      /* TODO:
>       * FP state
>       */
> @@ -310,6 +312,8 @@ int kvm_arch_get_registers(CPUState *cs)
>       */
>      write_list_to_cpustate(cpu);
>
> +    kvm_arm_sync_mpstate_to_qemu(cpu);
> +
>      /* TODO: other registers */
>      return ret;
>  }
> diff --git a/target-arm/kvm_arm.h b/target-arm/kvm_arm.h
> index 455dea3..7b75758 100644
> --- a/target-arm/kvm_arm.h
> +++ b/target-arm/kvm_arm.h
> @@ -162,6 +162,24 @@ typedef struct ARMHostCPUClass {
>   */
>  bool kvm_arm_get_host_cpu_features(ARMHostCPUClass *ahcc);
>
> +
> +/**
> + * kvm_arm_sync_mpstate_to_kvm
> + * @cpu: ARMCPU
> + *
> + * If supported set the KVM MP_STATE based on QEMUs migration data.

Apostrophes (again!). And the reference to migration data
here is spurious.


> + */
> +int kvm_arm_sync_mpstate_to_kvm(ARMCPU *cpu);
> +
> +/**
> + * kvm_arm_sync_mpstate_to_qemu
> + * @cpu: ARMCPU
> + *
> + * If supported get the MP_STATE from KVM and store in QEMUs migration
> + * data.
> + */
> +int kvm_arm_sync_mpstate_to_qemu(ARMCPU *cpu);
> +
>  #endif
>
>  #endif
> --
> 2.3.2

-- PMM