[PATCH v6 05/28] s390x/diag: Introduce DIAG 320 for Certificate Store Facility

[Zhuoying Cai <zycai@linux.ibm.com>]

DIAGNOSE 320 is introduced to support Certificate Store (CS)
Facility, which includes operations such as query certificate
storage information and provide certificates in the certificate
store.

Currently, only subcode 0 is supported with this patch, which is
used to query the Installed Subcodes Mask (ISM).

This subcode is only supported when the CS facility is enabled.

Availability of CS facility is determined by byte 134 bit 5 of the
SCLP Read Info block. Byte 134's facilities cannot be represented
without the availability of the extended-length-SCCB, so add it as
a check for consistency.

Note: secure IPL is not available for Secure Execution (SE) guests,
as their images are already integrity protected, and an additional
protection of the kernel by secure IPL is not necessary.

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>
---
 docs/specs/s390x-secure-ipl.rst     | 12 ++++++++
 include/hw/s390x/ipl/diag320.h      | 20 +++++++++++++
 target/s390x/cpu_features.c         |  1 +
 target/s390x/cpu_features_def.h.inc |  1 +
 target/s390x/cpu_models.c           |  2 ++
 target/s390x/diag.c                 | 44 +++++++++++++++++++++++++++++
 target/s390x/gen-features.c         |  3 ++
 target/s390x/kvm/kvm.c              | 16 +++++++++++
 target/s390x/s390x-internal.h       |  2 ++
 target/s390x/tcg/misc_helper.c      |  7 +++++
 10 files changed, 108 insertions(+)
 create mode 100644 include/hw/s390x/ipl/diag320.h

diff --git a/docs/specs/s390x-secure-ipl.rst b/docs/specs/s390x-secure-ipl.rst
index 9b1de5c604..30ddc81c2b 100644
--- a/docs/specs/s390x-secure-ipl.rst
+++ b/docs/specs/s390x-secure-ipl.rst
@@ -13,3 +13,15 @@ will keep track of the number of certificates, their respective size,
 and a summation of the sizes.
 
 Note: A maximum of 64 certificates are allowed to be stored in the certificate store.
+
+DIAGNOSE function code 'X'320' - Certificate Store Facility
+-----------------------------------------------------------
+
+DIAGNOSE 'X'320' is used to provide support for userspace to directly
+query the s390 certificate store. Userspace may be the s390-ccw BIOS or
+the guest kernel.
+
+Subcode 0 - query installed subcodes
+    Returns a 256-bit installed subcodes mask (ISM) stored in the installed
+    subcodes block (ISB). This mask indicates which sucodes are currently
+    installed and available for use.
diff --git a/include/hw/s390x/ipl/diag320.h b/include/hw/s390x/ipl/diag320.h
new file mode 100644
index 0000000000..aa04b699c6
--- /dev/null
+++ b/include/hw/s390x/ipl/diag320.h
@@ -0,0 +1,20 @@
+/*
+ * S/390 DIAGNOSE 320 definitions and structures
+ *
+ * Copyright 2025 IBM Corp.
+ * Author(s): Zhuoying Cai <zycai@linux.ibm.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef S390X_DIAG320_H
+#define S390X_DIAG320_H
+
+#define DIAG_320_SUBC_QUERY_ISM     0
+
+#define DIAG_320_RC_OK              0x0001
+#define DIAG_320_RC_NOT_SUPPORTED   0x0102
+
+#define DIAG_320_ISM_QUERY_SUBCODES 0x80000000
+
+#endif
diff --git a/target/s390x/cpu_features.c b/target/s390x/cpu_features.c
index 4b5be6798e..436471f4b4 100644
--- a/target/s390x/cpu_features.c
+++ b/target/s390x/cpu_features.c
@@ -147,6 +147,7 @@ void s390_fill_feat_block(const S390FeatBitmap features, S390FeatType type,
         break;
     case S390_FEAT_TYPE_SCLP_FAC134:
         clear_be_bit(s390_feat_def(S390_FEAT_DIAG_318)->bit, data);
+        clear_be_bit(s390_feat_def(S390_FEAT_CERT_STORE)->bit, data);
         break;
     default:
         return;
diff --git a/target/s390x/cpu_features_def.h.inc b/target/s390x/cpu_features_def.h.inc
index c017bffcdc..941a69e013 100644
--- a/target/s390x/cpu_features_def.h.inc
+++ b/target/s390x/cpu_features_def.h.inc
@@ -138,6 +138,7 @@ DEF_FEAT(SIE_IBS, "ibs", SCLP_CONF_CHAR_EXT, 10, "SIE: Interlock-and-broadcast-s
 
 /* Features exposed via SCLP SCCB Facilities byte 134 (bit numbers relative to byte-134) */
 DEF_FEAT(DIAG_318, "diag318", SCLP_FAC134, 0, "Control program name and version codes")
+DEF_FEAT(CERT_STORE, "cstore", SCLP_FAC134, 5, "Provide Certificate Store functions")
 
 /* 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 954a7a99a9..6b8471700e 100644
--- a/target/s390x/cpu_models.c
+++ b/target/s390x/cpu_models.c
@@ -248,6 +248,7 @@ bool s390_has_feat(S390Feat feat)
     if (s390_is_pv()) {
         switch (feat) {
         case S390_FEAT_DIAG_318:
+        case S390_FEAT_CERT_STORE:
         case S390_FEAT_HPMA2:
         case S390_FEAT_SIE_F2:
         case S390_FEAT_SIE_SKEY:
@@ -505,6 +506,7 @@ static void check_consistency(const S390CPUModel *model)
         { S390_FEAT_PTFF_STOUE, S390_FEAT_MULTIPLE_EPOCH },
         { S390_FEAT_AP_QUEUE_INTERRUPT_CONTROL, S390_FEAT_AP },
         { S390_FEAT_DIAG_318, S390_FEAT_EXTENDED_LENGTH_SCCB },
+        { S390_FEAT_CERT_STORE, S390_FEAT_EXTENDED_LENGTH_SCCB },
         { 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/diag.c b/target/s390x/diag.c
index cff9fbc4b0..a35d808fd7 100644
--- a/target/s390x/diag.c
+++ b/target/s390x/diag.c
@@ -18,6 +18,7 @@
 #include "hw/watchdog/wdt_diag288.h"
 #include "system/cpus.h"
 #include "hw/s390x/ipl.h"
+#include "hw/s390x/ipl/diag320.h"
 #include "hw/s390x/s390-virtio-ccw.h"
 #include "system/kvm.h"
 #include "kvm/kvm_s390x.h"
@@ -191,3 +192,46 @@ out:
         break;
     }
 }
+
+void handle_diag_320(CPUS390XState *env, uint64_t r1, uint64_t r3, uintptr_t ra)
+{
+    S390CPU *cpu = env_archcpu(env);
+    uint64_t subcode = env->regs[r3];
+    uint64_t addr = env->regs[r1];
+
+    if (env->psw.mask & PSW_MASK_PSTATE) {
+        s390_program_interrupt(env, PGM_PRIVILEGED, ra);
+        return;
+    }
+
+    if (!s390_has_feat(S390_FEAT_CERT_STORE)) {
+        s390_program_interrupt(env, PGM_SPECIFICATION, ra);
+        return;
+    }
+
+    if ((subcode & ~0x000ffULL) || (r1 & 1)) {
+        s390_program_interrupt(env, PGM_SPECIFICATION, ra);
+        return;
+    }
+
+    switch (subcode) {
+    case DIAG_320_SUBC_QUERY_ISM:
+        /*
+         * The Installed Subcode Block (ISB) can be up 8 words in size,
+         * but the current set of subcodes can fit within a single word
+         * for now.
+         */
+        uint32_t ism_word0 = cpu_to_be32(DIAG_320_ISM_QUERY_SUBCODES);
+
+        if (s390_cpu_virt_mem_write(cpu, addr, r1, &ism_word0, sizeof(ism_word0))) {
+            s390_cpu_virt_mem_handle_exc(cpu, ra);
+            return;
+        }
+
+        env->regs[r1 + 1] = DIAG_320_RC_OK;
+        break;
+    default:
+        env->regs[r1 + 1] = DIAG_320_RC_NOT_SUPPORTED;
+        break;
+    }
+}
diff --git a/target/s390x/gen-features.c b/target/s390x/gen-features.c
index 8218e6470e..6c20c3a862 100644
--- a/target/s390x/gen-features.c
+++ b/target/s390x/gen-features.c
@@ -720,6 +720,7 @@ static uint16_t full_GEN16_GA1[] = {
     S390_FEAT_PAIE,
     S390_FEAT_UV_FEAT_AP,
     S390_FEAT_UV_FEAT_AP_INTR,
+    S390_FEAT_CERT_STORE,
 };
 
 static uint16_t full_GEN17_GA1[] = {
@@ -919,6 +920,8 @@ static uint16_t qemu_MAX[] = {
     S390_FEAT_KIMD_SHA_512,
     S390_FEAT_KLMD_SHA_512,
     S390_FEAT_PRNO_TRNG,
+    S390_FEAT_EXTENDED_LENGTH_SCCB,
+    S390_FEAT_CERT_STORE,
 };
 
 /****** END FEATURE DEFS ******/
diff --git a/target/s390x/kvm/kvm.c b/target/s390x/kvm/kvm.c
index 8ee33924df..5510fc2fc5 100644
--- a/target/s390x/kvm/kvm.c
+++ b/target/s390x/kvm/kvm.c
@@ -98,6 +98,7 @@
 #define DIAG_TIMEREVENT                 0x288
 #define DIAG_IPL                        0x308
 #define DIAG_SET_CONTROL_PROGRAM_CODES  0x318
+#define DIAG_CERT_STORE                 0x320
 #define DIAG_KVM_HYPERCALL              0x500
 #define DIAG_KVM_BREAKPOINT             0x501
 
@@ -1560,6 +1561,16 @@ static void handle_diag_318(S390CPU *cpu, struct kvm_run *run)
     }
 }
 
+static void kvm_handle_diag_320(S390CPU *cpu, struct kvm_run *run)
+{
+    uint64_t r1, r3;
+
+    r1 = (run->s390_sieic.ipa & 0x00f0) >> 4;
+    r3 = run->s390_sieic.ipa & 0x000f;
+
+    handle_diag_320(&cpu->env, r1, r3, RA_IGNORED);
+}
+
 #define DIAG_KVM_CODE_MASK 0x000000000000ffff
 
 static int handle_diag(S390CPU *cpu, struct kvm_run *run, uint32_t ipb)
@@ -1590,6 +1601,9 @@ static int handle_diag(S390CPU *cpu, struct kvm_run *run, uint32_t ipb)
     case DIAG_KVM_BREAKPOINT:
         r = handle_sw_breakpoint(cpu, run);
         break;
+    case DIAG_CERT_STORE:
+        kvm_handle_diag_320(cpu, run);
+        break;
     default:
         trace_kvm_insn_diag(func_code);
         kvm_s390_program_interrupt(cpu, PGM_SPECIFICATION);
@@ -2490,6 +2504,8 @@ bool kvm_s390_get_host_cpu_model(S390CPUModel *model, Error **errp)
         set_bit(S390_FEAT_DIAG_318, model->features);
     }
 
+    set_bit(S390_FEAT_CERT_STORE, model->features);
+
     /* Test for Ultravisor features that influence secure guest behavior */
     query_uv_feat_guest(model->features);
 
diff --git a/target/s390x/s390x-internal.h b/target/s390x/s390x-internal.h
index 56cce2e7f5..ecff2d07a1 100644
--- a/target/s390x/s390x-internal.h
+++ b/target/s390x/s390x-internal.h
@@ -391,6 +391,8 @@ int mmu_translate_real(CPUS390XState *env, target_ulong raddr, int rw,
 int handle_diag_288(CPUS390XState *env, uint64_t r1, uint64_t r3);
 void handle_diag_308(CPUS390XState *env, uint64_t r1, uint64_t r3,
                      uintptr_t ra);
+void handle_diag_320(CPUS390XState *env, uint64_t r1, uint64_t r3,
+                     uintptr_t ra);
 
 
 /* translate.c */
diff --git a/target/s390x/tcg/misc_helper.c b/target/s390x/tcg/misc_helper.c
index f7101be574..412c34ed93 100644
--- a/target/s390x/tcg/misc_helper.c
+++ b/target/s390x/tcg/misc_helper.c
@@ -142,6 +142,13 @@ void HELPER(diag)(CPUS390XState *env, uint32_t r1, uint32_t r3, uint32_t num)
         /* time bomb (watchdog) */
         r = handle_diag_288(env, r1, r3);
         break;
+    case 0x320:
+        /* cert store */
+        bql_lock();
+        handle_diag_320(env, r1, r3, GETPC());
+        bql_unlock();
+        r = 0;
+        break;
     default:
         r = -1;
         break;
-- 
2.50.1