[PATCH v2 08/25] s390x/diag: Introduce DIAG 508 for secure IPL operations

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

From: Collin Walling <walling@linux.ibm.com>

In order to support secure IPL (aka secure boot) for the s390-ccw BIOS,
a new s390 DIAGNOSE instruction is introduced to leverage QEMU for
handling operations such as signature verification and certificate
retrieval.

Currently, only subcode 0 is supported with this patch, which is used to
query a bitmap of which subcodes are supported.

Signed-off-by: Collin Walling <walling@linux.ibm.com>
---
 hw/s390x/ipl.h                 |  1 +
 include/hw/s390x/ipl/diag508.h | 15 +++++++++++++++
 target/s390x/diag.c            | 26 ++++++++++++++++++++++++++
 target/s390x/kvm/kvm.c         | 14 ++++++++++++++
 target/s390x/s390x-internal.h  |  2 ++
 5 files changed, 58 insertions(+)
 create mode 100644 include/hw/s390x/ipl/diag508.h

diff --git a/hw/s390x/ipl.h b/hw/s390x/ipl.h
index 254cf6a46a..b4d4566293 100644
--- a/hw/s390x/ipl.h
+++ b/hw/s390x/ipl.h
@@ -20,6 +20,7 @@
 #include "system/memory.h"
 #include "hw/qdev-core.h"
 #include "hw/s390x/ipl/diag320.h"
+#include "hw/s390x/ipl/diag508.h"
 #include "hw/s390x/ipl/qipl.h"
 #include "qom/object.h"
 #include "target/s390x/kvm/pv.h"
diff --git a/include/hw/s390x/ipl/diag508.h b/include/hw/s390x/ipl/diag508.h
new file mode 100644
index 0000000000..6281ad8299
--- /dev/null
+++ b/include/hw/s390x/ipl/diag508.h
@@ -0,0 +1,15 @@
+/*
+ * S/390 DIAGNOSE 508 definitions and structures
+ *
+ * Copyright 2025 IBM Corp.
+ * Author(s): Collin Walling <walling@linux.ibm.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef S390X_DIAG508_H
+#define S390X_DIAG508_H
+
+#define DIAG_508_SUBC_QUERY_SUBC    0x0000
+
+#endif
diff --git a/target/s390x/diag.c b/target/s390x/diag.c
index 6fd59ac863..954c95fe50 100644
--- a/target/s390x/diag.c
+++ b/target/s390x/diag.c
@@ -491,3 +491,29 @@ void handle_diag_320(CPUS390XState *env, uint64_t r1, uint64_t r3, uintptr_t ra)
     }
     env->regs[r1 + 1] = rc;
 }
+
+void handle_diag_508(CPUS390XState *env, uint64_t r1, uint64_t r3, uintptr_t ra)
+{
+    uint64_t subcode = env->regs[r3];
+    int rc;
+
+    if (env->psw.mask & PSW_MASK_PSTATE) {
+        s390_program_interrupt(env, PGM_PRIVILEGED, ra);
+        return;
+    }
+
+    if ((subcode & ~0x0ffffULL) || (r1 & 1)) {
+        s390_program_interrupt(env, PGM_SPECIFICATION, ra);
+        return;
+    }
+
+    switch (subcode) {
+    case DIAG_508_SUBC_QUERY_SUBC:
+        rc = 0;
+        break;
+    default:
+        s390_program_interrupt(env, PGM_SPECIFICATION, ra);
+        return;
+    }
+    env->regs[r1 + 1] = rc;
+}
diff --git a/target/s390x/kvm/kvm.c b/target/s390x/kvm/kvm.c
index 3ae00b9a6d..9bf3ed694b 100644
--- a/target/s390x/kvm/kvm.c
+++ b/target/s390x/kvm/kvm.c
@@ -101,6 +101,7 @@
 #define DIAG_CERT_STORE                 0x320
 #define DIAG_KVM_HYPERCALL              0x500
 #define DIAG_KVM_BREAKPOINT             0x501
+#define DIAG_SECURE_IPL                 0x508
 
 #define ICPT_INSTRUCTION                0x04
 #define ICPT_PROGRAM                    0x08
@@ -1572,6 +1573,16 @@ static void kvm_handle_diag_320(S390CPU *cpu, struct kvm_run *run)
     handle_diag_320(&cpu->env, r1, r3, RA_IGNORED);
 }
 
+static void kvm_handle_diag_508(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_508(&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)
@@ -1605,6 +1616,9 @@ static int handle_diag(S390CPU *cpu, struct kvm_run *run, uint32_t ipb)
     case DIAG_CERT_STORE:
         kvm_handle_diag_320(cpu, run);
         break;
+    case DIAG_SECURE_IPL:
+        kvm_handle_diag_508(cpu, run);
+        break;
     default:
         trace_kvm_insn_diag(func_code);
         kvm_s390_program_interrupt(cpu, PGM_SPECIFICATION);
diff --git a/target/s390x/s390x-internal.h b/target/s390x/s390x-internal.h
index 86a652f833..df0973266a 100644
--- a/target/s390x/s390x-internal.h
+++ b/target/s390x/s390x-internal.h
@@ -402,6 +402,8 @@ 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);
+void handle_diag_508(CPUS390XState *env, uint64_t r1, uint64_t r3,
+                     uintptr_t ra);
 
 
 /* translate.c */
-- 
2.49.0