From: Andrew Jones <drjones@redhat.com>
Date: Sun, 4 Jun 2017 14:43:56 +0200
Subject: KVM: arm/arm64: use vcpu requests for power_off
Patch-mainline: v4.13-rc1
Git-commit: cc9b43f99d5ff4df75d11e75c0bfaf08f1ff5a9a
References: bsc#1077761

System shutdown is currently using request-less VCPU kicks. This
leaves open a tiny race window, as it doesn't ensure the state
change to power_off is seen by a VCPU just about to enter guest
mode. VCPU requests, OTOH, are guaranteed to be seen (see "Ensuring
Requests Are Seen" of Documentation/virtual/kvm/vcpu-requests.rst)
This patch applies the EXIT request used by pause to power_off,
fixing the race.

Signed-off-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Christoffer Dall <cdall@linaro.org>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
Acked-by: Alexander Graf <agraf@suse.de>
---
 virt/kvm/arm/psci.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/virt/kvm/arm/psci.c
+++ b/virt/kvm/arm/psci.c
@@ -179,10 +179,9 @@
 	 * after this call is handled and before the VCPUs have been
 	 * re-initialized.
 	 */
-	kvm_for_each_vcpu(i, tmp, vcpu->kvm) {
+	kvm_for_each_vcpu(i, tmp, vcpu->kvm)
 		tmp->arch.power_off = true;
-		kvm_vcpu_kick(tmp);
-	}
+	kvm_make_all_cpus_request(vcpu->kvm, KVM_REQ_VCPU_EXIT);
 
 	memset(&vcpu->run->system_event, 0, sizeof(vcpu->run->system_event));
 	vcpu->run->system_event.type = type;