Re: [Qemu-devel] [PATCH v9 1/6] target-arm: kvm64 - introduce kvm_arm_init_debug()

[Peter Maydell]

On 12 November 2015 at 16:20, Alex Bennée <address@hidden> wrote:
> As we haven't always had guest debug support we need to probe for it.
> Additionally we don't do this in the start-up capability code so we
> don't fall over on old kernels.
>
> Signed-off-by: Alex Bennée <address@hidden>
> ---
>  target-arm/kvm64.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
>
> diff --git a/target-arm/kvm64.c b/target-arm/kvm64.c
> index ceebfeb..d087794 100644
> --- a/target-arm/kvm64.c
> +++ b/target-arm/kvm64.c
> @@ -25,6 +25,22 @@
>  #include "internals.h"
>  #include "hw/arm/arm.h"
>
> +static bool have_guest_debug;
> +
> +/**
> + * kvm_arm_init_debug()
> + * @cs: CPUState
> + *
> + * Check for guest debug capabilities.
> + *
> + */
> +static void kvm_arm_init_debug(CPUState *cs)
> +{
> +    have_guest_debug = kvm_check_extension(cs->kvm_state,
> +                                           KVM_CAP_SET_GUEST_DEBUG);
> +    return;
> +}
> +
>  static inline void set_feature(uint64_t *features, int feature)
>  {
>      *features |= 1ULL << feature;
> @@ -121,6 +137,8 @@ int kvm_arch_init_vcpu(CPUState *cs)
>      }
>      cpu->mp_affinity = mpidr & ARM64_AFFINITY_MASK;
>
> +    kvm_arm_init_debug(cs);
> +
>      return kvm_arm_init_cpreg_list(cpu);
>  }

I assume in practice the kernel guarantees that either all
CPUs have the SET_GUEST_DEBUG cap, or none do :-)

Reviewed-by: Peter Maydell <address@hidden>

thanks
-- PMM