s390/kvm: basic implementation of diagnose 308 subcode 6

Linux uses a check for subcode 6 to decide if other subcodes are
available. Provide a minimal implementation for subcode 6, as well
as for subcode 5.
Signed-off-by: NEugene (jno) Dvurechenski <jno@linux.vnet.ibm.com>
Reviewed-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
[Move code from kvm.c into misc_helper.c]

target-s390x/cpu.h

@@ -1047,6 +1047,9 @@ uint32_t set_cc_nz_f64(float64 v);
 uint32_t set_cc_nz_f128(float128 v);
 
 /* misc_helper.c */
+#ifndef CONFIG_USER_ONLY
+void handle_diag_308(CPUS390XState *env, uint64_t r1, uint64_t r3);
+#endif
 void program_interrupt(CPUS390XState *env, uint32_t code, int ilen);
 void QEMU_NORETURN runtime_exception(CPUS390XState *env, int excp,
                                      uintptr_t retaddr);

target-s390x/kvm.c

@@ -72,6 +72,7 @@
 #define PRIV_XSCH                       0x76
 #define PRIV_SQBS                       0x8a
 #define PRIV_EQBS                       0x9c
+#define DIAG_IPL                        0x308
 #define DIAG_KVM_HYPERCALL              0x500
 #define DIAG_KVM_BREAKPOINT             0x501
 
@@ -578,11 +579,24 @@ static int handle_hypercall(S390CPU *cpu, struct kvm_run *run)
     return 0;
 }
 
+static void kvm_handle_diag_308(S390CPU *cpu, struct kvm_run *run)
+{
+    uint64_t r1, r3;
+
+    cpu_synchronize_state(CPU(cpu));
+    r1 = (run->s390_sieic.ipa & 0x00f0) >> 8;
+    r3 = run->s390_sieic.ipa & 0x000f;
+    handle_diag_308(&cpu->env, r1, r3);
+}
+
 static int handle_diag(S390CPU *cpu, struct kvm_run *run, int ipb_code)
 {
     int r = 0;
 
     switch (ipb_code) {
+    case DIAG_IPL:
+        kvm_handle_diag_308(cpu, run);
+        break;
     case DIAG_KVM_HYPERCALL:
         r = handle_hypercall(cpu, run);
         break;

target-s390x/misc_helper.c

@@ -179,6 +179,46 @@ uint32_t HELPER(servc)(CPUS390XState *env, uint64_t r1, uint64_t r2)
     return r;
 }
 
+#ifndef CONFIG_USER_ONLY
+#define DIAG_308_RC_NO_CONF         0x0102
+#define DIAG_308_RC_INVALID         0x0402
+void handle_diag_308(CPUS390XState *env, uint64_t r1, uint64_t r3)
+{
+    uint64_t addr =  env->regs[r1];
+    uint64_t subcode = env->regs[r3];
+
+    if (env->psw.mask & PSW_MASK_PSTATE) {
+        program_interrupt(env, PGM_PRIVILEGED, ILEN_LATER_INC);
+        return;
+    }
+
+    if ((subcode & ~0x0ffffULL) || (subcode > 6)) {
+        program_interrupt(env, PGM_SPECIFICATION, ILEN_LATER_INC);
+        return;
+    }
+
+    switch (subcode) {
+    case 5:
+        if ((r1 & 1) || (addr & 0x0fffULL)) {
+            program_interrupt(env, PGM_SPECIFICATION, ILEN_LATER_INC);
+            return;
+        }
+        env->regs[r1+1] = DIAG_308_RC_INVALID;
+        return;
+    case 6:
+        if ((r1 & 1) || (addr & 0x0fffULL)) {
+            program_interrupt(env, PGM_SPECIFICATION, ILEN_LATER_INC);
+            return;
+        }
+        env->regs[r1+1] = DIAG_308_RC_NO_CONF;
+        return;
+    default:
+        hw_error("Unhandled diag308 subcode %" PRIx64, subcode);
+        break;
+    }
+}
+#endif
+
 /* DIAG */
 uint64_t HELPER(diag)(CPUS390XState *env, uint32_t num, uint64_t mem,
                       uint64_t code)