4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: James Morse <james.morse@xxxxxxx>
commit 58d6b15e9da5042a99c9c30ad725792e4569150e upstream.
cpu_pm_enter() calls the pm notifier chain with CPU_PM_ENTER, then if
there is a failure: CPU_PM_ENTER_FAILED.
When KVM receives CPU_PM_ENTER it calls cpu_hyp_reset() which will
return us to the hyp-stub. If we subsequently get a CPU_PM_ENTER_FAILED,
KVM does nothing, leaving the CPU running with the hyp-stub, at odds
with kvm_arm_hardware_enabled.
Add CPU_PM_ENTER_FAILED as a fallthrough for CPU_PM_EXIT, this reloads
KVM based on kvm_arm_hardware_enabled. This is safe even if CPU_PM_ENTER
never gets as far as KVM, as cpu_hyp_reinit() calls cpu_hyp_reset()
to make sure the hyp-stub is loaded before reloading KVM.
Fixes: 67f691976662 ("arm64: kvm: allows kvm cpu hotplug")
CC: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Reviewed-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
Signed-off-by: James Morse <james.morse@xxxxxxx>
Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm/kvm/arm.c | 1 +
1 file changed, 1 insertion(+)
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -1165,6 +1165,7 @@ static int hyp_init_cpu_pm_notifier(stru
cpu_hyp_reset();
return NOTIFY_OK;
+ case CPU_PM_ENTER_FAILED:
case CPU_PM_EXIT:
if (__this_cpu_read(kvm_arm_hardware_enabled))
/* The hardware was enabled before suspend. */