Real hardware would use an external device to control the power.
But for the moment let's invent an instruction in reserved space.

Suggested-by: Helge Deller <deller@gmx.de>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/hppa/helper.h    |  1 +
 target/hppa/op_helper.c |  7 +++++++
 target/hppa/translate.c | 18 +++++++++++++++++-
 3 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/target/hppa/helper.h b/target/hppa/helper.h
index 1e733b7926..6e86c596fe 100644
--- a/target/hppa/helper.h
+++ b/target/hppa/helper.h
@@ -80,6 +80,7 @@ DEF_HELPER_FLAGS_4(fmpynfadd_d, TCG_CALL_NO_RWG, i64, env, i64, i64, i64)
 DEF_HELPER_FLAGS_0(read_interval_timer, TCG_CALL_NO_RWG, tr)
 
 #ifndef CONFIG_USER_ONLY
+DEF_HELPER_1(shutdown, noreturn, env)
 DEF_HELPER_1(rfi, void, env)
 DEF_HELPER_1(rfi_r, void, env)
 DEF_HELPER_FLAGS_2(write_interval_timer, TCG_CALL_NO_RWG, void, env, tr)
diff --git a/target/hppa/op_helper.c b/target/hppa/op_helper.c
index d270f94e31..88be2ebf24 100644
--- a/target/hppa/op_helper.c
+++ b/target/hppa/op_helper.c
@@ -22,6 +22,7 @@
 #include "exec/exec-all.h"
 #include "exec/helper-proto.h"
 #include "exec/cpu_ldst.h"
+#include "sysemu/sysemu.h"
 #include "qemu/timer.h"
 
 
@@ -639,6 +640,12 @@ void HELPER(write_interval_timer)(CPUHPPAState *env, target_ureg val)
     timer_mod(cpu->alarm_timer, timeout);
 }
 
+void HELPER(shutdown)(CPUHPPAState *env)
+{
+    qemu_system_shutdown_request(SHUTDOWN_CAUSE_GUEST_SHUTDOWN);
+    helper_excp(env, EXCP_HLT);
+}
+
 target_ureg HELPER(swap_system_mask)(CPUHPPAState *env, target_ureg nsm)
 {
     target_ulong psw = env->psw;
diff --git a/target/hppa/translate.c b/target/hppa/translate.c
index 00a8c26afa..68f0b86c72 100644
--- a/target/hppa/translate.c
+++ b/target/hppa/translate.c
@@ -2293,6 +2293,14 @@ static DisasJumpType trans_rfi(DisasContext *ctx, uint32_t insn,
     /* Exit the TB to recognize new interrupts.  */
     return nullify_end(ctx, DISAS_NORETURN);
 }
+
+static DisasJumpType gen_hlt(DisasContext *ctx)
+{
+    CHECK_MOST_PRIVILEGED(EXCP_PRIV_OPR);
+    nullify_over(ctx);
+    gen_helper_shutdown(cpu_env);
+    return nullify_end(ctx, DISAS_NORETURN);
+}
 #endif /* !CONFIG_USER_ONLY */
 
 static const DisasInsn table_system[] = {
@@ -4510,7 +4518,15 @@ static DisasJumpType translate_one(DisasContext *ctx, uint32_t insn)
     case 0x15: /* unassigned */
     case 0x1D: /* unassigned */
     case 0x37: /* unassigned */
-    case 0x3F: /* unassigned */
+        break;
+    case 0x3F:
+#ifndef CONFIG_USER_ONLY
+        /* Unassigned, but use as system-halt.  */
+        if (insn == 0xffffffff) {
+            return gen_hlt(ctx);
+        }
+#endif
+        break;
     default:
         break;
     }
-- 
2.14.3