4.15-stable review patch. If anyone has any objections, please let me know.
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From: James Morse james.morse@arm.com
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@arm.com Reviewed-by: Christoffer Dall christoffer.dall@linaro.org Signed-off-by: James Morse james.morse@arm.com Signed-off-by: Christoffer Dall christoffer.dall@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- virt/kvm/arm/arm.c | 1 + 1 file changed, 1 insertion(+)
--- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -1239,6 +1239,7 @@ 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. */