Re: [PATCH v4 21/28] s390x: Guest support for Secure-IPL Code Loading Attributes Facility (SCLAF)

[Collin Walling <walling@linux.ibm.com>]

On 7/11/25 5:10 PM, Zhuoying Cai wrote:
> The secure-IPL-code-loading-attributes facility (SCLAF)
> provides additional security during IPL.
> 
> Availability of SCLAF is determined by byte 136 bit 3 of the
> SCLP Read Info block.
> 
> Signed-off-by: Zhuoying Cai <zycai@linux.ibm.com>

Aside from the comment I made in patch 17, LGTM.

Reviewed-by: Collin Walling <walling@linux.ibm.com>

> ---
>  target/s390x/cpu_features.c         | 1 +
>  target/s390x/cpu_features_def.h.inc | 1 +
>  target/s390x/cpu_models.c           | 3 +++
>  target/s390x/gen-features.c         | 2 ++
>  target/s390x/kvm/kvm.c              | 3 +++
>  5 files changed, 10 insertions(+)
> 
> diff --git a/target/s390x/cpu_features.c b/target/s390x/cpu_features.c
> index 3f3d6a80af..8d5614fa59 100644
> --- a/target/s390x/cpu_features.c
> +++ b/target/s390x/cpu_features.c
> @@ -151,6 +151,7 @@ void s390_fill_feat_block(const S390FeatBitmap features, S390FeatType type,
>          break;
>      case S390_FEAT_TYPE_SCLP_FAC_IPL:
>          clear_be_bit(s390_feat_def(S390_FEAT_SIPL)->bit, data);
> +        clear_be_bit(s390_feat_def(S390_FEAT_SCLAF)->bit, data);
>          break;
>      default:
>          return;
> diff --git a/target/s390x/cpu_features_def.h.inc b/target/s390x/cpu_features_def.h.inc
> index 956bd8a123..2e91817d75 100644
> --- a/target/s390x/cpu_features_def.h.inc
> +++ b/target/s390x/cpu_features_def.h.inc
> @@ -142,6 +142,7 @@ DEF_FEAT(DIAG_320, "cstore", SCLP_FAC134, 5, "Provide Certificate Store function
>  
>  /* Features exposed via SCLP SCCB Facilities byte 136 - 137 (bit numbers relative to byte-136) */
>  DEF_FEAT(SIPL, "sipl", SCLP_FAC_IPL, 1, "Secure-IPL facility")
> +DEF_FEAT(SCLAF, "sclaf", SCLP_FAC_IPL, 3, "Secure-IPL-code-loading-attributes facility")
>  
>  /* Features exposed via SCLP CPU info. */
>  DEF_FEAT(SIE_F2, "sief2", SCLP_CPU, 4, "SIE: interception format 2 (Virtual SIE)")
> diff --git a/target/s390x/cpu_models.c b/target/s390x/cpu_models.c
> index ab46204d9e..cb1c6b5350 100644
> --- a/target/s390x/cpu_models.c
> +++ b/target/s390x/cpu_models.c
> @@ -264,6 +264,7 @@ bool s390_has_feat(S390Feat feat)
>          case S390_FEAT_SIE_PFMFI:
>          case S390_FEAT_SIE_IBS:
>          case S390_FEAT_SIPL:
> +        case S390_FEAT_SCLAF:
>          case S390_FEAT_CONFIGURATION_TOPOLOGY:
>              return false;
>              break;
> @@ -509,6 +510,8 @@ static void check_consistency(const S390CPUModel *model)
>          { S390_FEAT_DIAG_318, S390_FEAT_EXTENDED_LENGTH_SCCB },
>          { S390_FEAT_DIAG_320, S390_FEAT_EXTENDED_LENGTH_SCCB },
>          { S390_FEAT_SIPL, S390_FEAT_EXTENDED_LENGTH_SCCB },
> +        { S390_FEAT_SCLAF, S390_FEAT_EXTENDED_LENGTH_SCCB },
> +        { S390_FEAT_SCLAF, S390_FEAT_SIPL },
>          { S390_FEAT_NNPA, S390_FEAT_VECTOR },
>          { S390_FEAT_RDP, S390_FEAT_LOCAL_TLB_CLEARING },
>          { S390_FEAT_UV_FEAT_AP, S390_FEAT_AP },
> diff --git a/target/s390x/gen-features.c b/target/s390x/gen-features.c
> index 6ee9bad4c6..987e291cf9 100644
> --- a/target/s390x/gen-features.c
> +++ b/target/s390x/gen-features.c
> @@ -722,6 +722,7 @@ static uint16_t full_GEN16_GA1[] = {
>      S390_FEAT_UV_FEAT_AP_INTR,
>      S390_FEAT_DIAG_320,
>      S390_FEAT_SIPL,
> +    S390_FEAT_SCLAF,
>  };
>  
>  static uint16_t full_GEN17_GA1[] = {
> @@ -924,6 +925,7 @@ static uint16_t qemu_MAX[] = {
>      S390_FEAT_EXTENDED_LENGTH_SCCB,
>      S390_FEAT_DIAG_320,
>      S390_FEAT_SIPL,
> +    S390_FEAT_SCLAF,
>  };
>  
>  /****** END FEATURE DEFS ******/
> diff --git a/target/s390x/kvm/kvm.c b/target/s390x/kvm/kvm.c
> index fc9cad32a1..be3ad7316d 100644
> --- a/target/s390x/kvm/kvm.c
> +++ b/target/s390x/kvm/kvm.c
> @@ -2523,6 +2523,9 @@ bool kvm_s390_get_host_cpu_model(S390CPUModel *model, Error **errp)
>      /* Secure-IPL facility is handled entirely within QEMU */
>      set_bit(S390_FEAT_SIPL, model->features);
>  
> +    /* Secure-IPL-code-loading-attributes facility is handled entirely within QEMU */
> +    set_bit(S390_FEAT_SCLAF, model->features);
> +
>      /* Test for Ultravisor features that influence secure guest behavior */
>      query_uv_feat_guest(model->features);
>  


-- 
Regards,
  Collin