riscv: sifive_test: Add reset functionality

This adds a reset opcode for sifive_test device to trigger a system
reset for testing purpose.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

hw/riscv/sifive_test.c

@@ -22,6 +22,7 @@
 #include "hw/hw.h"
 #include "hw/sysbus.h"
 #include "qemu/module.h"
+#include "sysemu/runstate.h"
 #include "target/riscv/cpu.h"
 #include "hw/hw.h"
 #include "hw/riscv/sifive_test.h"
@@ -42,6 +43,9 @@ static void sifive_test_write(void *opaque, hwaddr addr,
             exit(code);
         case FINISHER_PASS:
             exit(0);
+        case FINISHER_RESET:
+            qemu_system_reset_request(SHUTDOWN_CAUSE_GUEST_RESET);
+            return;
         default:
             break;
         }

include/hw/riscv/sifive_test.h

@@ -36,7 +36,8 @@ typedef struct SiFiveTestState {
 
 enum {
     FINISHER_FAIL = 0x3333,
-    FINISHER_PASS = 0x5555
+    FINISHER_PASS = 0x5555,
+    FINISHER_RESET = 0x7777
 };
 
 DeviceState *sifive_test_create(hwaddr addr);