Patch "KVM: arm/arm64: Handle CPU_PM_ENTER_FAILED" has been added to the 4.15-stable tree

Patch "KVM: arm/arm64: Handle CPU_PM_ENTER_FAILED" has been added to the 4.15-stable tree

[gregkh]

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 4.15-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-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 58d6b15e9da5042a99c9c30ad725792e4569150e Mon Sep 17 00:00:00 2001
From: James Morse <james.morse@arm.com>
Date: Mon, 22 Jan 2018 18:19:06 +0000
Subject: KVM: arm/arm64: Handle CPU_PM_ENTER_FAILED

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. */


Patches currently in stable-queue which might be from james.morse@arm.com are

queue-4.15/arm64-kpti-fix-the-interaction-between-asid-switching-and-software-pan.patch
queue-4.15/kvm-arm-arm64-handle-cpu_pm_enter_failed.patch
queue-4.15/arm64-cpufeature-__this_cpu_has_cap-shouldn-t-stop-early.patch