Patch "KVM: arm/arm64: Handle CPU_PM_ENTER_FAILED" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

KVM: arm/arm64: Handle CPU_PM_ENTER_FAILED

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
kvm-arm-arm64-handle-cpu_pm_enter_failed.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: James Morse <[email protected]>
Date: Mon, 22 Jan 2018 18:19:06 +0000
Subject: KVM: arm/arm64: Handle CPU_PM_ENTER_FAILED

From: James Morse <[email protected]>

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.

---
 arch/arm/kvm/arm.c |    1 +
 1 file changed, 1 insertion(+)

@@ -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. */

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/kvm-arm-arm64-handle-cpu_pm_enter_failed.patch