[PULL 27/37] s390x: Guest support for Secure-IPL Code Loading Attributes Facility (SCLAF)

[Eric Farman <farman@linux.ibm.com>]

From: Zhuoying Cai <zycai@linux.ibm.com>

The secure-IPL-code-loading-attributes facility (SCLAF)
provides additional security during secure IPL.

Availability of SCLAF is determined by byte 136 bit 3 of the
SCLP Read SCP Info.

This feature is available starting with the gen16 CPU model.

Signed-off-by: Zhuoying Cai <zycai@linux.ibm.com>
Reviewed-by: Collin Walling <walling@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20260730214624.2328883-26-zycai@linux.ibm.com
Signed-off-by: Eric Farman <farman@linux.ibm.com>
---
 docs/specs/s390x-secure-ipl.rst     | 18 ++++++++++++++++++
 target/s390x/cpu_features.c         |  2 ++
 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              |  1 +
 6 files changed, 27 insertions(+)

diff --git a/docs/specs/s390x-secure-ipl.rst b/docs/specs/s390x-secure-ipl.rst
index 113acbeda9..7a603eb956 100644
--- a/docs/specs/s390x-secure-ipl.rst
+++ b/docs/specs/s390x-secure-ipl.rst
@@ -122,3 +122,21 @@ The guest kernel uses the contents in the IIRB for:
 * Boot logging: reports which components were loaded and verified.
 * kexec operations: builds the next kernel’s IPL report from the existing one.
 * Keying: installs IPL certificates into the platform trusted keyring.
+
+Secure Code Loading Attributes Facility
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The Secure Code Loading Attributes Facility (SCLAF) enhances system security
+during the IPL by enforcing additional verification rules.
+
+When SCLAF is available, its behavior depends on the IPL mode. It introduces
+verification of both signed and unsigned components to help ensure that only
+authorized code is loaded during the IPL process. Any errors detected by SCLAF
+are reported in the IIRB.
+
+Unsigned components are restricted to load addresses at or above absolute
+storage address ``0x2000``.
+
+Signed components must include a Secure Code Loading Attribute Block (SCLAB),
+which is appended at the very end of the component. The SCLAB defines security
+attributes for handling the signed code.
diff --git a/target/s390x/cpu_features.c b/target/s390x/cpu_features.c
index 27f38636a9..c634e74123 100644
--- a/target/s390x/cpu_features.c
+++ b/target/s390x/cpu_features.c
@@ -120,6 +120,7 @@ void s390_fill_feat_block(const S390FeatBitmap features, S390FeatType type,
      * - All SIE facilities because SIE is not available
      * - DIAG318
      * - Secure IPL Facility
+     * - Secure IPL Code Loading Attributes Facility
      *
      * As VMs can move in and out of protected mode the CPU model
      * doesn't protect us from that problem because it is only
@@ -152,6 +153,7 @@ 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;
     case S390_FEAT_TYPE_SCLP_FAC139:
         clear_be_bit(s390_feat_def(S390_FEAT_SIE_ASTFLEIE2)->bit, data);
diff --git a/target/s390x/cpu_features_def.h.inc b/target/s390x/cpu_features_def.h.inc
index 0153a6aa67..a5aa19112a 100644
--- a/target/s390x/cpu_features_def.h.inc
+++ b/target/s390x/cpu_features_def.h.inc
@@ -142,6 +142,7 @@ DEF_FEAT(CERT_STORE, "cstore", SCLP_FAC134, 5, "Certificate Store functions")
 
 /* 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 SCCB Facilities byte 139 (bit numbers relative to byte-139) */
 DEF_FEAT(SIE_ASTFLEIE2, "astfleie2", SCLP_FAC139, 1, "SIE: ASTFLE interpretation execution facility 2")
diff --git a/target/s390x/cpu_models.c b/target/s390x/cpu_models.c
index 97e77f2bfa..c41d629d68 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:
         case S390_FEAT_SIE_ASTFLEIE2:
             return false;
@@ -510,6 +511,8 @@ static void check_consistency(const S390CPUModel *model)
         { S390_FEAT_DIAG_318, S390_FEAT_EXTENDED_LENGTH_SCCB },
         { S390_FEAT_CERT_STORE, 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 6bf61447de..a99a75d14e 100644
--- a/target/s390x/gen-features.c
+++ b/target/s390x/gen-features.c
@@ -723,6 +723,7 @@ static uint16_t full_GEN16_GA1[] = {
     S390_FEAT_SIE_ASTFLEIE2,
     S390_FEAT_CERT_STORE,
     S390_FEAT_SIPL,
+    S390_FEAT_SCLAF,
 };
 
 static uint16_t full_GEN17_GA1[] = {
@@ -925,6 +926,7 @@ static uint16_t qemu_MAX[] = {
     S390_FEAT_EXTENDED_LENGTH_SCCB,
     S390_FEAT_CERT_STORE,
     S390_FEAT_SIPL,
+    S390_FEAT_SCLAF,
 };
 
 /****** END FEATURE DEFS ******/
diff --git a/target/s390x/kvm/kvm.c b/target/s390x/kvm/kvm.c
index 70c9933d7f..b34a912714 100644
--- a/target/s390x/kvm/kvm.c
+++ b/target/s390x/kvm/kvm.c
@@ -2504,6 +2504,7 @@ bool kvm_s390_get_host_cpu_model(S390CPUModel *model, Error **errp)
 
     /* Some Secure IPL facilities are emulated by QEMU */
     set_bit(S390_FEAT_SIPL, model->features);
+    set_bit(S390_FEAT_SCLAF, model->features);
 
     /* Test for Ultravisor features that influence secure guest behavior */
     query_uv_feat_guest(model->features);
-- 
2.55.0