[PATCH v2] efi/arm64: use UEFI for system reset and poweroff

[Ard Biesheuvel]

If UEFI Runtime Services are available, they are preferred over direct
PSCI calls or other methods to reset the system.

For the reset case, we need to hook into machine_restart(), as the
arm_pm_restart function pointer may be overwritten by modules.

Tested-by: Mark Rutland <mark.rutland at arm.com>
Reviewed-by: Mark Rutland <mark.rutland at arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
---
 arch/arm64/kernel/efi.c     | 9 +++++++++
 arch/arm64/kernel/process.c | 8 ++++++++
 2 files changed, 17 insertions(+)

diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index b42c7b480e1e..2b8d70164428 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -354,3 +354,12 @@ void efi_virtmap_unload(void)
 	efi_set_pgd(current->active_mm);
 	preempt_enable();
 }
+
+/*
+ * UpdateCapsule() depends on the system being shutdown via
+ * ResetSystem().
+ */
+bool efi_poweroff_required(void)
+{
+	return efi_enabled(EFI_RUNTIME_SERVICES);
+}
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index fde9923af859..c6b1f3b96f45 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -21,6 +21,7 @@
 #include <stdarg.h>
 
 #include <linux/compat.h>
+#include <linux/efi.h>
 #include <linux/export.h>
 #include <linux/sched.h>
 #include <linux/kernel.h>
@@ -150,6 +151,13 @@ void machine_restart(char *cmd)
 	local_irq_disable();
 	smp_send_stop();
 
+	/*
+	 * UpdateCapsule() depends on the system being reset via
+	 * ResetSystem().
+	 */
+	if (efi_enabled(EFI_RUNTIME_SERVICES))
+		efi_reboot(reboot_mode, NULL);
+
 	/* Now call the architecture specific reboot code. */
 	if (arm_pm_restart)
 		arm_pm_restart(reboot_mode, cmd);
-- 
1.8.3.2