arm64: hibernate: Don't hibernate on systems with stuck CPUs

Hibernate relies on cpu hotplug to prevent secondary cores executing
the kernel text while it is being restored.

Add a call to cpus_are_stuck_in_kernel() to determine if there are
CPUs not counted by 'num_online_cpus()', and prevent hibernate in this
case.

Fixes: 82869ac57b5 ("arm64: kernel: Add support for hibernate/suspend-to-disk")
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
index f8df75d740f4891a018aa84e02cb7c2988f3ff84..21ab5df9fa76ddea54d58abf77812593ddbb0f6d 100644 (file)
--- a/arch/arm64/kernel/hibernate.c
+++ b/arch/arm64/kernel/hibernate.c
@@ -33,6 +33,7 @@
 #include <asm/pgtable.h>
 #include <asm/pgtable-hwdef.h>
 #include <asm/sections.h>
+#include <asm/smp.h>
 #include <asm/suspend.h>
 #include <asm/virt.h>
 
@@ -236,6 +237,11 @@ int swsusp_arch_suspend(void)
        unsigned long flags;
        struct sleep_stack_data state;
 
+       if (cpus_are_stuck_in_kernel()) {
+               pr_err("Can't hibernate: no mechanism to offline secondary CPUs.\n");
+               return -EBUSY;
+       }
+
        local_dbg_save(flags);
 
        if (__cpu_suspend_enter(&state)) {