KVM: arm/arm64: use vcpu requests for power_off

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>

diff --git a/virt/kvm/arm/psci.c b/virt/kvm/arm/psci.c
index f68be2cc6256763cc197dc79a65556d71543242f..f189d0ad30d5028dba6ccda12265fcb356af39e1 100644 (file)
--- a/virt/kvm/arm/psci.c
+++ b/virt/kvm/arm/psci.c
@@ -179,10 +179,9 @@ static void kvm_prepare_system_event(struct kvm_vcpu *vcpu, u32 type)
         * 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;