Re: [PATCH v2 2/2] s390x: pv: Fix diag318 PV fencing

[Christian Borntraeger]

On 22.10.20 12:31, Janosch Frank wrote:
> Diag318 fencing needs to be determined on the current VM PV state and
> not on the state that the VM has when we create the CPU model.
> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com>
> Fixes: fabdada935 ("s390: guest support for diagnose 0x318")

I prefer v1 as it is more obvious what happens, but this looks fine as well
and as David prefers this let us go with this one.

Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>

> ---
>  target/s390x/cpu_features.c | 5 +++++
>  target/s390x/cpu_features.h | 4 ++++
>  target/s390x/cpu_models.c   | 4 ++++
>  target/s390x/kvm.c          | 3 +--
>  4 files changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/target/s390x/cpu_features.c b/target/s390x/cpu_features.c
> index 31ea8df246..42fe0bf4ca 100644
> --- a/target/s390x/cpu_features.c
> +++ b/target/s390x/cpu_features.c
> @@ -14,6 +14,7 @@
>  #include "qemu/osdep.h"
>  #include "qemu/module.h"
>  #include "cpu_features.h"
> +#include "hw/s390x/pv.h"
>  
>  #define DEF_FEAT(_FEAT, _NAME, _TYPE, _BIT, _DESC) \
>      [S390_FEAT_##_FEAT] = {                        \
> @@ -105,6 +106,10 @@ void s390_fill_feat_block(const S390FeatBitmap features, 
> S390FeatType type,
>          }
>          feat = find_next_bit(features, S390_FEAT_MAX, feat + 1);
>      }
> +
> +    if (type == S390_FEAT_TYPE_SCLP_FAC134 && s390_is_pv()) {
> +        clear_be_bit(s390_feat_def(S390_FEAT_DIAG_318)->bit, data);
> +    }
>  }
>  
>  void s390_add_from_feat_block(S390FeatBitmap features, S390FeatType type,
> diff --git a/target/s390x/cpu_features.h b/target/s390x/cpu_features.h
> index ef52ffce83..87463f064d 100644
> --- a/target/s390x/cpu_features.h
> +++ b/target/s390x/cpu_features.h
> @@ -81,6 +81,10 @@ const S390FeatGroupDef *s390_feat_group_def(S390FeatGroup 
> group);
>  
>  #define BE_BIT_NR(BIT) (BIT ^ (BITS_PER_LONG - 1))
>  
> +static inline void clear_be_bit(unsigned int bit_nr, uint8_t *array)
> +{
> +    array[bit_nr / 8] &= ~(0x80 >> (bit_nr % 8));
> +}
>  static inline void set_be_bit(unsigned int bit_nr, uint8_t *array)
>  {
>      array[bit_nr / 8] |= 0x80 >> (bit_nr % 8);
> diff --git a/target/s390x/cpu_models.c b/target/s390x/cpu_models.c
> index ca484bfda7..461e0b8f4a 100644
> --- a/target/s390x/cpu_models.c
> +++ b/target/s390x/cpu_models.c
> @@ -29,6 +29,7 @@
>  #include "hw/pci/pci.h"
>  #endif
>  #include "qapi/qapi-commands-machine-target.h"
> +#include "hw/s390x/pv.h"
>  
>  #define CPUDEF_INIT(_type, _gen, _ec_ga, _mha_pow, _hmfai, _name, _desc) \
>      {                                                                    \
> @@ -238,6 +239,9 @@ bool s390_has_feat(S390Feat feat)
>          }
>          return 0;
>      }
> +    if (feat == S390_FEAT_DIAG_318 && s390_is_pv()) {
> +        return false;
> +    }
>      return test_bit(feat, cpu->model->features);
>  }
>  
> diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
> index f13eff688c..baa070fdf7 100644
> --- a/target/s390x/kvm.c
> +++ b/target/s390x/kvm.c
> @@ -2498,8 +2498,7 @@ void kvm_s390_get_host_cpu_model(S390CPUModel *model, 
> Error **errp)
>       */
>      set_bit(S390_FEAT_EXTENDED_LENGTH_SCCB, model->features);
>  
> -    /* DIAGNOSE 0x318 is not supported under protected virtualization */
> -    if (!s390_is_pv() && kvm_check_extension(kvm_state, 
> KVM_CAP_S390_DIAG318)) {
> +    if (kvm_check_extension(kvm_state, KVM_CAP_S390_DIAG318)) {
>          set_bit(S390_FEAT_DIAG_318, model->features);
>      }
>  
>