sandbox: implement runtime system reset

Implement a reset function that we can call after ExitBootServices(),
when all driver model devices are gone.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/sandbox/cpu/start.c b/arch/sandbox/cpu/start.c
index f6c9854..fe494ae 100644
--- a/arch/sandbox/cpu/start.c
+++ b/arch/sandbox/cpu/start.c
@@ -6,6 +6,7 @@
 #include <common.h>
 #include <command.h>
 #include <dm/root.h>
+#include <efi_loader.h>
 #include <errno.h>
 #include <init.h>
 #include <os.h>
@@ -406,6 +407,15 @@
 	printf("\n");
 }
 
+void __efi_runtime EFIAPI efi_reset_system(
+		enum efi_reset_type reset_type,
+		efi_status_t reset_status,
+		unsigned long data_size, void *reset_data)
+{
+	os_fd_restore();
+	os_relaunch(os_argv);
+}
+
 void sandbox_reset(void)
 {
 	/* Do this here while it still has an effect */
diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
index 8746e10..073d90c 100644
--- a/lib/efi_loader/Kconfig
+++ b/lib/efi_loader/Kconfig
@@ -233,7 +233,8 @@
 	# bool "Reset runtime service is available"
 	bool
 	default y
-	depends on ARCH_BCM283X || FSL_LAYERSCAPE || PSCI_RESET || SYSRESET_X86
+	depends on ARCH_BCM283X || FSL_LAYERSCAPE || PSCI_RESET || \
+		   SANDBOX || SYSRESET_X86
 
 config EFI_GRUB_ARM32_WORKAROUND
 	bool "Workaround for GRUB on 32bit ARM"